Cassava is an important cash crop in Southern China, which is enriched with starch in the tuber roots. The analysis of the regulation mechanism of starch synthesis in cassava root would contribute to the improvement of yield and high starch molecular in cassava. AGPase is composed of large subunit and small subunit, and it catalyzes G-1-P and ATP to form ADPG and PPi, in which ADPG is the substrate of starch biosynthesis. Therefore, AGPase is a rate-limiting enzyme in plant starch synthesis, and improving the activity of AGPase is beneficial for the accumulation of crop starch and the improvement of yield. The small subunit encoded by MeAGPS1a is the catalytic center of AGPase in cassava. Previous studies have shown that the growth response factor MeSAUR1 as a transcription factor positively regulates the expression of MeAGPS1a gene, and yeast two-hybrid screening of a cassava cDNA library revealed that the calmodulin-like (CML) member MeCML24 is a candidate interacting protein of MeSAUR1. To determine the interaction between MeCML24 and MeSAUR1, and MeCML24 was cloned from the genome of SC8 cassava variety in this study. The length of CDS region of MeCML24 was 492 bp, encoding 163 amino acids. The physicochemical properties and secondary structure analysis of MeCML24 showed that the value of theoretical pI was 4.38, which belonging to hydrophilic protein with α-helix accounting for 52.76%, random coil accounting for 30.06%, and beta turn accounting for 11.04%. Yeast two-hybrid vector BD-MeCML24 was constructed, and the self-activation experiment showed that MeCML24 had no self-activation. Yeast two-hybrid point-to-point experiment revealed that yeast strains co-transfected with AD-MeSAUR1 and BD-MeCML24 plasmids turned blue on nutrient medium with SD/TLHA+x-α-gal, indicating that MeCML24 interacted with MeSAUR1. The fusion protein MeSAUR1-nEYFP and MeCML24-cEYFP were co-expressed in tobacco leaves by bimolecular fluorescence complementation (BiFC) experiment, and the fluorescence signal of yellow fluorescent protein EYFP was detected under laser confocal microscope, which further proved the interaction between MeCML24 and MeSAUR1. Finally, the interaction between MeCML24 and MeSAUR1 negatively regulated the expression of MeAGPS1a by double luciferase experiment. The study revealed the mechanism of MeSAUR1 and MeCML24 synergistically regulating MeAGPS1a gene expression in cassava, and found that the calmodulin-like protein MeCML24 regulating the expression of MeAGPS1a, a key gene for starch synthesis in cassava root. This study would provide a theoretical basis for cultivating excellent cassava varieties by molecular biology technology.

Cassava is an important food crop in tropical regions. Cassava bacterial blight caused by Xanthomonas phoseoli pv. manihotis (Xpm) is an important disease of cassava. Excavating and identifying the genes of cassava resistance to Xpm and analyzing its disease resistance mechanism are beneficial to the development of cassava disease-resistant germplasm. Plant heat shock transcription factors (Hsfs) play an important role in the process of plants resisting biotic and abiotic stresses. In this study, the full-length heat shock protein transcription factor gene MeHsfB3a was cloned from cassava cultivar 'Huanan 8' ('SC8') by RT-PCR technology. Bioinformatics analysis found that MeHsfB3a contained two exons and one intron, with a full length of 729 bp, encoding 242 amino acids with 27.9 kDa and pI=7.59. The theoretical instability coefficient was 56.86, which is an unstable protein, and the average hydrophilicity index was-0.880, indicating that the protein has good water solubility, and the fat solubility index was 65.98. The protein was predicted to localize in the nucleus. qRT-PCR analysis found that MeHsfB3a was expressed in young leaves, mature leaves, terminal buds, petioles, tuberous roots and fibrous roots, with the highest expression in mature leaves and less in other organs. The expression of MeHsfB3a was analyzed after 0 h, 3 h, 6 h, 1 d, 3 d and 6 d after infection of cassava 'SC8' leaves by pathogen XpmHN11, and it was found that the expression of this gene was significantly increased after 1 d. This indicated that MeHsfB3a was involved in the response of 'SC8' cassava to XpmHN11. The MeHsfB3a gene of cassava 'SC8' was silenced by the VIGS technology, and the gene silencing efficiency reached 68.26%-82.44%. The leaves of silent plants were inoculated with XpmHN11, and the disease incidence was analyzed on 0 d, 3 d, and 6 d of inoculation, and it was found that the area of disease spots of the silent plants was significantly higher than that of the control. This study identified the heat shock protein transcription factor gene MeHsfB3a involved in the process of cassava resistance to XpmHN11, which would help to further analyze the disease resistance mechanism of cassava to cassava bacterial blight.

Passion fruit (Passiflora edulia Sims), as an emerging tropical fruit tree, plays a very important role in tropical agriculture. However, abiotic stresses such as drought and high temperature seriously affect its normal growth and development. Relevant studies have shown that aquaporin (AQP) can improve the stress resistance of plants. In this study, Passiflora 'Tainong' was used as the material, an aquaporin gene PePIP2 was cloned using the genome data of passion fruit. The open reading frame (ORF) was 861 bp, encoding 286 amino acids. The molecular formula was C₁₄₁₇H₂₁₅₆N₃₆₀O₃₇₃S₈, the molecular weight was 30 459.37 Da, the isoelectric point was 8.84, and the subcellular localization was on the cell membrane. Analysis of the promoter region revealed that it contained cis-acting elements involved in stress response. The expression analysis showed that PePIP2 could be induced by drought, high temperature and low temperature stress. Among them, the expression level was the highest when the soil water content was 50%, treated at 45℃ for 4 h and at 0℃ for 48 h. Transiently expressed in tobacco, the expression of PePIP2 was also induced to varying degrees under drought stress at different times. The results of this study would lay the foundation for the analysis of the stress resistance mechanism and molecular breeding of the passion fruit.

Tigernut (Cyperus esculentus L.) is a perennial herb that is native to Africa and the Mediterranean coast. Due to the shortage of edible vegetable oil and biodiesel in China, tigernut has been emerging as a promising oil crop for its wide adaptability and high oil production per unit. To promote the development and utilization of this special crop, EPSPS (5-enolpyruvylshikimate-3-phosphate synthase) genes, which encode a key enzyme targeted by herbicide glyphosate in the shikimate pathway for the synthesis of aromatic amino acids, were identified from tigernut as well as several representative monocots based on genome and transcriptome data available. Comparative analyses revealed that (a) tigernut harbors a single EPSPS gene (denoted CeEPSPS) with seven introns as observed in most plant species; (b) its complete coding sequence of 1584 bp was further isolated using RT-PCR; (c) among 514 amino acids encoded by CeEPSPS, the first 70 residues from the N-terminal were characterized as the chloroplast signal peptide, whereas the peptide from sites 77 to 508 belongs to the highly conserved EPSP_ synthase domain (under the Pfam accession number of PF00275); (d) compared with the EPSP_ synthase domain, the chloroplast signal peptide is relatively more variable; and (e) the maturation protein of CeEPSPS was predicted to possess the theoretical molecular weight (Mw) of 47.32 kDa, the isolectric point (pI) of 5.49, the grand average of hydropathicity (GRAVY) of 0.069, the aliphatic index (AI) of 93.76, and the instability index (II) of 31.73, which is similar to other reported EPSPSs and could be categorized as a type of hydrophilic, acidic, and stable proteins; (f) phylogenetic analysis using deduced EPSPS proteins supports that tigernut is a Cyperaceae plant within Poales. Further sequence alignment and genome resequencing analyses revealed that no target site resistance mutations to glyphosate were found in all 56 germplasms investigated in this study. Gene expression analysis using qRT-PCR showed that CeEPSPS was dominantly expressed in mature leaves and tubers, which were significantly higher than that in buds, young leaves, senescent leaves, and rhizomes. Additionally, a plant vector of over-expressing CeEPSPS was also constructed, which would lay a solid foundation for the following molecular breeding for glyphosate resistant in tigernut and other species.

Harvested cucumber is sensitive to low temperature, which is subjected to chilling injury during cold storage and causes heavy postharvest losses. In this study, the method of RNA sequencing combined with bioinformatics analysis was used to analyze the transcriptomic changes of harvested cucumber when subjected to a short-term of cold treatment. The chilling injury index (CII) and relative electrical conductivity (REC) gradually increased but the chlorophyll fluorescence (F_v/F_m) decreased with increasing time when stored at 5℃, indicating that the chilling injury was obviously occurred. Compared with that before treatment (0 h), treatment at 5℃ for 12 h resulted in 2679 differentially expressed genes (DEGs), of which 1194 DEGs were up-regulated and 1485 DEGs were down regulated. Compared with treatment for 0 h, treatment for 72 h resulted in 9494 DEGs, of which 4807 DEGs were up-regulated and 4687 DEGs were down regulated. The results of KEGG enrichment analysis showed that the DEGs caused by cold treatment were most significantly enriched in the pathways of plant hormone signal transduction, phenylalanine metabolism, plant pathway interaction and phenylpropanoid biosynthesis. The results of GO enrichment analysis showed that DEGs were mainly involved in regulation of transcription DNA templated, protein phosphorylation and transmembrane transport in biological process. In cellular component, most enriched DEGs were related to organelle components such as membrane and nucleus. In molecular function, the enriched DEGs were mainly involved in ATP binding, protein serine/threonine kinase activity, DNA binding and transcription factor activity. DEGs related to hormone signal were significantly expressed when cucumber fruits were cold-treated for 12 h. However, the DEGs related to plant pathogen interaction and phenylpropanoid synthesis were significantly induced following 72 h of cold treatment. The results showed that plant hormone participated in the transmission of low temperature signals, the induced pathogenesis-related gene and phenylpropanoid biosynthesis might be important mechanisms for harvested cucumbers to improve chilling tolerance and cope with chilling stress. The results would provide new insights into the molecular mechanisms of harvested cucumber adaptation and resistance to chilling stress, and identify a lot of key gene resources for breeding cold-tolerant cucumber.

In this study, 100 matreials of innovative germplasm from Yunnan octoploid Saccharum spontaneum L. 84-268 bloodline F₂ population were used as materials, and 7 main agronomic factors including plant height, stalk diameter, brix, effective stalk number, single stalk weight, cane yield and sugar yield were measured, and frequency distribution histogram analysis, coefficient of variation analysis, correlation analysis, principal component analysis and cluster analysis were done. The results showed that the data of the 7 agronomic traits presented a good normal distribution and abundant variation with the variation coefficient ranging from 9.91% to 50.76%, and the maximum variation coefficient of sugar yield was 50.76%. Correlation analysis and stepwise regression analysis showed that the cane yield was significantly and positively correlated with plant height, stalk diameter and effective stalk number, having a determination coefficient of 0.9282. The sugar yield was mainly determined by plant height, stalk diameter, brix, single stalk weight and effective stalk number, and the coefficient of determination was 0.9160. The seven agronomic traits were integrated into three main components by principal component analysis, and the cumulative contribution rate was 86.985%. The first principal component, cane yield and sugar factor, was the most important factor, which contributing rate was 47.615%. At the Euclidean distance of 6.00, the 100 innovative materials were divided into 3 categories, and the results were consistent with the principal component scoring. The 7 traits were excellent in group Ⅰ, and a total of 15 high-quality materials were screened out, which had a high principal component score. In particular, it was worth of paying high attention to YGF₂18-226-7, YGF₂18-226-14, YGF₂18-226-89, YGF₂18-226-48, YGF₂18-226-96, YGF₂18-226-21, YGF₂18-226-43 and YGF₂18-226-5. These materials can be further screened as the parents or reserved as core germplasm for breeding research.

In order to meet the demand for high-quality leguminous forage varieties in southern livestock production, comprehensive evaluation of the botanical characters of high-quality breeding resources is the premise of breeding. Dendrolobium triangulare is a perennial shrub with large leaves, high yield and high nutritional value. It is an excellent high-protein green feed. At present, there are only studies on the genetic diversity among the subgroups of the locust, and the analysis and research on the morphological genetic diversity of the genus Desmodium Desv. are relatively scarce, and there is a lack of research on the morphological genetic diversity of germplasm in a large range. In this experiment, a random block design was adopted, and the research materials were 76 germplasm resources of the genus Desmodium Desv. 35 botanical traits were observed, and the genetic diversity characteristics of Desmodium Desv spp. were analyzed for future breeding work of Desmodium Desv. Provide basic materials. The genetic diversity was studied by morphological observational analysis. The 35 botanical traits, the hair condition on the back of the leaf (CV=46.92%), the color of the stem (CV=39.77%) and the condition of the petiole hair (CV=39.52%) had the largest coefficients of variation, indicating that the false D. triangulare. was rich in genetic diversity. There were correlations among several botanical characters, there was a very significant positive correlation between leaf length and leaf width (r=0.887), the aspect ratio was about 2.0, and the leaf shape was close to ellipse. There was a correlation between the shape of the stem and the length of the leaf (r=-0.459) and the width of the leaf (r=-0.491), indicating that if the yield of pseudo pigeon is mainly based on the leaf area, the cylindrical stem should be selected as much as possible. There was a very significant correlation between the leaf shape of the central leaflet and the length of the pod (r=0.360), so the selection of obovate leaves during breeding could improve the seed yield. There was a very significant correlation between the hair condition on the back of the leaf, the hair condition on the petiole (r=0.462) and the hair condition on the pod (r=0.589), indicating that the hair coat condition of the same plant has a high correlation, and the resources with less hair coat on the whole plant can be screened. Through cluster analysis and systematic evaluation, four germplasm resources were screened out (D. triangulare 070314022, D. triangulare GX121121004, D. triangulare 050218087, D. triangulare 050307492), and the germplasm resources had the characteristics of high yield and high quality. This experiment explored the characteristics of genetic diversity of botanical traits among the species of D. triangulare, which could provide basic materials for subsequent breeding work.

Two new records and one mainland new record of Dematiaceous hyphomycetes from China, Beltraniella fertilis Heredia, R.M. Arias, M. Reyes & R.F. Castañeda, Subulispora cylindrospora P.M. Kirk and Subulispora procurvata Tubaki wre reported. The specimens were collected from Kuankuoshui National Nature Reserve and Xishui National Nature Reserve of Guizhou. Morphological description, figures were provided for each species, ITS and LSU sequence were provided for B. fertilis and S. procurvata. The specimens are deposited in the Mycological Herbarium of Zunyi Normal College (HMZNC).

Rucheng Baimaocha (Camellia sinensis var. pubilimba Chang) is one of the four tea plants native to Hunan Province, China. Previous studies have shown that Rucheng Baimaocha is different from other three local population resources in Hunan in evolutionary status, and has distinctive characteristics in botanical characteristics, biochemical components and tea making quality. However, there are few studies on the differences of secondary metabolites of Rucheng Baimaocha germplasm resources. Using UPLC-MS/MS analysis technology, taking Anhua population (AHQT, C. sinensis var. sinensis), Chengbu Dongcha [CBDC, C. sinensis var. assamica (Masters) Kitamura], and Jianghua Kucha [JHKC, C. sinensis var. assamica (Masters) Kitamura] of typical local tea resources in Hunan as controls, the significantly different metabolites in Rucheng Baimaocha were screened and clustered by K-means analysis and differential metabolite enrichment pathway analysis. Compared with the control, 189, 180 and 162 significantly different metabolites were screened in Rucheng Baimaotea, the most species were flavonoids (69, 51 and 60 respectively), followed by phenolic acids (31, 40 and 25 respectively), and the least were lignans and coumarins (5, 4 and 4 respectively). Compared with the other three populations, Rucheng Baimaotea increased the content of 15 metabolites. The content of flavonoids and phenolic acids increased the most in Rucheng Baimaocha, and the highest increase was pinocembrin, followed by 1,2,3,6-tetra-o-galloyl-d-glucose. The differential metabolites were analyzed by K-means clustering. The metabolites with the same change trend in the four groups could be divided into nine categories. Among the four populations, there were 32 metabolites with the same change trend and the highest content in Rucheng Baimaotea, mainly flavonoids and tannins. The results of KEGG pathway enrichment of differential metabolites showed that the differential metabolites of Rucheng Baimaotea were mainly enriched in flavonoid biosynthesis pathway, flavonoid and flavonol biosynthesis pathway, phenylpropane biosynthesis pathway and so on. In addition to the differential metabolites reported in some tea, some differential metabolites less concerned in tea research were detected, such as pinocembrin, ellagic acid, kaempferol, etc. The substances would provide an important reference for the excavation and breeding of characteristic tea germplasm resources of Rucheng white tea in the later stage.

To investigate the characteristics of plant diversity in the understory of eucalyptus plantations in Hainan, vegetation surveys were conducted in different areas of eucalyptus plantations, and the biomass of the upper part of the interior of the sample plots was measured by combining the standard wood method and the harvesting method, then theα-diversity index of the irrigation and grass layers was combined with the biomass of the above-ground part to construct a comprehensive functional index, and the new index was compared with the α diversity index. There were 101 species of understory plants in eucalyptus plantation, among which 49 species appeared in shrub layer, belonging to 45 genera of 31 families, and 52 species appeared in herb layer, belonging to 48 genera of 28 families. There was no significant difference in the diversity index of understory shrub layer in different regions of eucalyptus plantations. The α diversity index of herbaceous layer in Lingao was significantly higher than that of other areas. It means the diversity level of shrub layer was similar, while the diversity level of herb layer was more affected by environment. There were significant differences in aboveground biomass allocation between shrub layer and grass layer in different regions. Although shrub layer was larger than herb layer, the distribution ratio fluctuated widely. Yd indices of shrub layer of eucalyptus plantations in different areas had no significant difference, and Yd indices of herb layer in Lingao and Ding'an were significantly higher than those in Tunchang and Dongfang. It means that the ecological functions of shrub layer in different areas were similar, while the ecological functions of herbaceous layer were obviously stronger than those of Lingao and Ding'an. The Yd index of the shrub layer was strongly correlated with the α-diversity index; the Yd index of the herb layer was generally correlated with the α diversity index and strongly correlated with above-ground biomass. The results show that the plant diversity characteristics of the eucalyptus understory are influenced by the regional environment, with the herbaceous layer being more susceptible than the shrub layer; the α-diversity index of the shrub layer has a greater influence on the Yd index, while the above-ground biomass of the herbaceous layer has a greater influence on the Yd index. The Yd index can reflect both the α-diversity level and biomass of the understory, and is a good complement to evaluate the ecological functions of the understory vegetation of eucalyptus plantations.

Low temperature is an important factor limiting the growth, development and yield of pitaya. 2,4-Epibrassinolide (EBR) can enhance the resistance of plants to various stresses such as low temperature. In order to improve the cold resistance of pitaya and alleviate the damage caused by low temperature, the cutting seedlings of red pulp pitaya 'Taiwan No. 6' was sprayed with 0.5 mg/L EBR, and treated under low temperature stress (4℃/0℃, 12 h/12 h) for 7 days. Reactive oxygen species (ROS) content, antioxidant enzyme activity, relative conductivity (REC), malondialdehyde (MDA) content, fatty acid composition and content were determined to clarify the regulatory effect of EBR on the cold tolerance of pitaya seedlings. Furthermore, the relationship between antioxidant system and fatty acid unsaturation of membrane lipids under low temperature stress was studied. Low temperature stress (4℃/0℃, 12 h/12 h) increased the content of reactive oxygen species (ROS), significantly decreased the content of unsaturated fatty acids. The fatty acids unsaturation (UFA/SFA) and double bond index (DBI) reduced by 32.1% and 32.4% respectively, and significantly increased the content of malondialdehyde (MDA) and relative conductivity (REC), resulting in decreased membrane stability and increased membrane permeability. The plants showed obvious watery stains and slight wilting, and the index of chilling injury reached 0.60. Under low temperature, exogenous EBR treatment increased the activities of superoxide dismutase, peroxidase and catalase, effectively removed the excessive accumulated ROS, significantly reduced the production rate of superoxide anion and the content of hydrogen peroxide, alleviated the oxidation reaction between ROS and unsaturated fatty acids in membrane lipids, and increased the relative content of unsaturated fatty acids in pitaya seedlings. The proportion of saturated fatty acids decreased significantly, UFA/SFA and DBI increased significantly, EBR maintained the stability of cell membrane, reduced REC and the content of membrane lipid peroxidation products MDA, greatly reduced watery stains of plants, and the index of chilling injury was reduced to 0.25. It is becouse EBR can activate the antioxidant enzyme system and effectively remove a large number of accumulated ROS under stress, leading to reduce the double-bond fracture of unsaturated fatty acids in membrane lipids, alleviate the degree of membrane lipid peroxidation, maintain the stability and function of membrane membrane. In conclusion, under low temperature stress, exogenous EBR can effectively improve the cold tolerance of pitaya seedlings. Its mechanism is by increasing the activity of antioxidant enzymes in pitaya seedlings, remove excess accumulated ROS, and significantly increase the unsaturation of cell membrane fatty acids, so as to reduce the degree of membrane lipid peroxidation and electrolyte leakage, maintain the stability and function of cell membranes.

With the rapid development of the livestock industry, the demand for forage is increasing, and it is urgent to screen new forage crop varieties. In this study, two national forage sugarcane varieties were used as the control. The biological yield of 15 sugarcane varieties and the routine nutritional components of 10 green fodder were measured and analyzed to explore the principal component variation of sugarcane at different cutting stages, and evaluate the feeding value of sugarcane, so as to provide scientific basis for more than one year of sugarcane harvest and whole plant feeding. Crude protein (CP), acid detergent fiber (ADF), water-soluble carbohydrate (WSC) and crude fat (EE) were selected by factor principal component analysis, which basically contained all the information of the indexes measured. Among the 15 sugarcane varieties, 'Yunzhe 12-201' had the highest CP content, which was 8.80 %, 'ROC22' with the lowest ADF content, 35.25 %. The highest WSC content was from 'Yunzhe 00-290', 6.16 %. The highest EE content was from 'Yunzhe 01-286', 1.40 %. The CP content of 'ROC22' and 'Yunzhe 12-201' was higher than that of CK1 and CK2. The ADF content of 'Q27','ROC22','Yunzhe 01-286', 'Yunzhe 06-160','Yunzhe 12-142-1-J', 'Dianzhe 11-728' was lower than that of CK1 and CK2. The WSC content of 'Q27', 'Yunzhe 00-290', 'Yunzhe 12-142-1-J', 'Yunzhe 16-16', 'Dianzhe 11-726' and 'Dianzhe 11-728' was higher than that of CK1 and CK2. There was no significant difference in EE content between 15 sugarcane varieties and CK1 (P>0.05), except 'Yunzhe 06-160'. There was no significant difference in EE content between 14 sugarcane varieties and CK2. Except for 'Dianzhe 11-726', there was no significant difference in Ca content between 14 varieties and CK1 and CK2. The CP content of all sugarcane varieties in the first cutting period was higher than that in the second cutting period, and the ADF, WSC, EE and Ca content in the first cutting period was higher than that in the second cutting period, with 12, 5, 4 and 14 sugarcane varieties, respectively. The total yield of 15 sugarcane was 71.40-163.95 t/hm², higher than that of CK1 and CK2. The yield of CP, ADF, WSC and EE per unit area of 15 sugarcane varieties exceeded that of CK1 and CK2, and the Ca yield of 15 sugarcane varieties exceeded that of CK2. Comprehensive evaluation showed that sugarcane could be used as ruminant feed with high nutritional value and economic benefit. In this study, five varieties 'Q27', 'ROC22', 'Yunzhe 01-286', 'Yunzhe 12-201', 'Dianzhe 11-728' were selected as the sources of forage sugarcane, which could not only meet the raw material needs of forage animals, but also form an industrial development model of sugar-animal linkage..

Youjiang River Valley in Baise is one of the famous dry and hot river valleys in China. Drought is the most serious meteorological disaster in the region. It has a unique suitable environment for mango and is the main mango producing area in China. However, the research on the water use strategy of Mango in Baise dry-hot river valley region is still lacking. Based on based on the measuring of hydrogen and oxygen stable isotope of precipitation, soil water at different layers, groundwater, and mango xylem water, the variation characteristics of hydrogen-oxygen isotope an its influencing factors of precipitation were analyzed, and the water absorption sources of mango roots at different growth stages were quantified. The hydrogen-oxygen stable isotopes and d-excess had obvious seasonal changes in the year, which were low in rainy season and high in dry season. The local meteoric water line was δD=8.2587δ¹⁸O+12.308 (r=0.9968, n=35, P<0.001) for the area. Under the influence of monsoon climate, the stable isotope value of precipitation had a significantly negative linear relationship with precipitation amounts and air temperature (P<0.05). During mango flowering stage, young fruit stage, fruit expansion stage, and mature stage, the stable isotopes of soil water became poor with the increase of soil depth. In the flowering stage and young fruit stage, mango trees used a relatively uniform proportion of soil water at different depths and groundwater, while in the expansion stage and maturity stage, mango trees mainly used deep soil water and groundwater, indicating that mango trees in this area mainly use deep soil water and groundwater as water sources, as mango trees' roots are mainly distributed in deep layers, and reveals its conservative water use strategies. The variation of hydrogen-oxygen stable isotopes of precipitation indicates the xerothermic environment of Baise dry-hot river valley region, and mango mainly uses deeper soil water and groundwater, the above results are expected to provide a basis for the sustainable development of mango industry in this area.

The effects of phosphorus (P) and lime application on yield and biomass and P uptake and utilization of sweet corn were evaluated with a field experiment. Research on the appropriate rate of P application would provide a theoretical basis in improving sweet corn yield and P use efficiency. The field experiment was a split-plot design with main-plot randomly assigned into each of four blocks. The main-plot treatments were four P application rates (0, 60, 120 and 180 kg/hm², expressed as P₀, P₆₀, P₁₂₀ and P₁₈₀). The split-plot factors were two lime levels (0 and 750 kg/hm², expressed as L₀ and L₁). The responses of sweet corn yield, P uptake, soil available P and P fertilizer utilization efficiency to P fertilizer application and lime application were studied. The yield of sweet corn increased significantly under P₁20 and P₁₈₀ treatments without lime by 19.4% and 18.5%, respectively, compared with P₀ treatment. Compared to P₀, the yield of sweet corn increased significantly by 14.0% under P₆₀ treatment with lime. Under P₆₀ treatment, lime increased the yield of sweet corn significantly by 12.7%. P fertilizer application increased both total biomass and P uptake of sweet corn significantly. After two sweet corn growing seasons, soil available P under P₆₀ treatment had no significant difference comparing with the original value. Soil available P basically maintained a balance under P₆₀ treatment. Soil available P in P₁₂₀ and P₁₈₀ treatments increased by 103.8% and 228.4%, respectively, compared with the original value, and soil available P increased obviously in 0-20 cm soil layer. The fresh ear yield per P uptake and P physiological efficiency decreased significantly with P application rates. Also, the P use efficiency of sweet corn declined with P application rates. P agronomic efficiency, recovery efficiency, and partial factor productivity increased significantly under lime treatments with P₆₀ treatment, compared with no-lime treatments. Together, these results indicated that the application of 60 kg/hm² P fertilizer combined with lime can be an efficient way to obtain high yield and P utilization efficiency of sweet corn and maintain the balance of soil available P.

This article aims to study the differences in the photosynthetic characteristics of different tea cultivars. The photosynthetic parameters in the leaves of nine tea cultivars were determined under field conditions, and the light response curves were drawn. The photosynthetic indicators of different tea cultivars were comprehensively evaluated by statistical analysis, principal component analysis, cluster, discrimination analysis and correlation analysis. There were great differences in net photosynthesis rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), intercellular CO₂ concentration (C_i). Among them, P_n, T_r of 'Yunshan' and 'Yunkang 10^#' were significantly higher than those of the other tea cultivars (P<0.05), G_s of 'Tian', 'Baohong' and 'Shilixiang' was significantly lower than that of the other tea cultivars (P<0.05), C_i of 'Changningdayezhong' was significantly lower than that of the other tea cultivars (P<0.05). At the beginning of photosynthetically active radiation (PAR), differences in the P_n between tea cultivars were not distinct. However, with the increase in PAR, great differences in P_n between tea cultivars appeared. The G_s and T_r of the nine tea cultivars showed two trends with the increase of PAR, 'Xiangguiyinhao' showing a first upward and then trend till to be stable, while other tea cultivars showing an overall upward trend. The C_i of the nine tea cultivars decreased rapidly at first and then tended to be stable. The WUE and iWUE increased first and then decreased with the increase of PAR, and the ability to tolerance of strong drought for 'Changningdayezhong' and 'Xiangguiyinhao' was better than that of the other tea cultivars with a higher WUE and iWUE, and both of them could be used as the drought tolerance tea cultivars suitable for breeding needs. The photosynthetic potential for 'Yunkang 10^#', 'Xiangguiyinhao', 'Yunashan' was better than the other tea cultivars with a higher P_nmax, and they could be used as the high-light-efficiency tea cultivars suitable for breeding needs. The LSP of 'Shilixiang', 'Changningdayezhong' and 'Zijuan' was significantly higher than that of other tea cultivars (P<0.05), and had a strong ability to use strong light. The strong ability to use low light for 'Xiangguiyinhao' and 'Shilixiang' was better than that of the other tea cultivars with a lower LCP (P<0.05). The nine tea cultivars were divided into four groups by principal components and cluster analysis. Correlation analysis indicated that P_n was significantly positively correlated with G_s and T_r (P<0.01).

Chilling injury during tobacco seedling stage is an important problem affecting tobacco agricultural production, and enhancement of the chilling resistance by various agronomic measures has practical significance. In this study, using two main cultivars Yunyan97 and K326 as the experimental materials, the seedlings were pretreated with salicylic acid (SA) at concentrations 0, 0.5, 1.0 and 1.5 mmol/L. Then the pretreated seedlings were transferred to 10℃ for 12 days for chilling treatment. Compared with the control without SA pretreatment, the SA pretreatment could significantly reduce the malondialdehyde (MDA) content and ratio of electrolyte leakage, slowed down the consumed rate of dry matter, increased chlorophyll content and root vigor, improve root length, surface area, volume and number of roots, promoted the growth of root system under the chilling stress, and finally enhanced the chilling resistance of 'Yunyan 97' and 'K326' seedlings. The optimum SA concentration of different tobacco varieties varied, that for 'Yunyan 97' and 'K326' was 1.5 mmol/L and 1.0 mmol/L respectively. After the SA pretreatment, the content of reduced ascorbic acid (ASA) and glutathione (GSH) in the antioxidant defense system in the seedlings remained a higher level, but oxidized ASA and GSH maintained a lower level, and ratio of the reduced antioxidants in total antioxidants increased. Ascorbate peroxidase (APX), catalase (CAT), guaiacol peroxidase (GPX), glutathione reductase (GR) and superoxide dismutase (SOD) maintained high activities compared with the control before and during the chilling treatment. The results indicated that after the SA pretreatment, the seedlings could maintain higher reduced antioxidant level and antioxidant enzyme activity, and remain higher antioxidant capacity, which would lay an important biochemical foundation for SA-induced chilling resistance in tobacco seedlings. The results would not only have reference significance for raising chilling-resistant tobacco seedlings, but also referential value for culture of seedlings and early cultivation of other crops and vegetables.

In this paper, a 3-factor fertilization experiment with N, P and K in an incomplete orthogonal design of "3414" was conducted to validate the optimal fertilization effect model, and the dry weight of single fruit and hesperidin content of Citrus medica 'Fingered' (CM) were used as the indicators for statistical analysis. The results showed that nitrogen, phosphorus and potassium fertilizers had effects on the dry weight of single fruit and hesperidin content in CM and N₂P₂K₂ (40g/plant for N, 40g/plant for P and 45g/plant for K) had the best effect among the different fertilization treatments, and no or less fertilization led to the decrease of quality of CM in Wanzhou to different degrees. The two-factor interaction analysis showed that when any of the N, P and K fertilizers were at the level of 2, with the increase of the other two factors, the single fruit dry weight and hesperidin content of CM showed a trend of increasing and then decreasing, indicating that any two factors interacted with each other within a certain range, and two of the N, P and K factors had an interaction effect. The optimization results of the fertilization model indicated that the suitable fertilization rates of N, P and K for cultivation of CM in Wanzhou ranged from 38.78 g to 51.25 g per plant, 35.67 g to 42.35 g per plant and 48.17 g to 60.37 g per plant, respectively. The results of the validation experiments under the intermediate conditions of the optimal fertilizer application effect model showed that the dry weight yield of single fruit of CM was 8.14% higher than that of the highest group of "3414", and the hesperidin content was 1.94% higher than that of the highest group of "3414". This indicates that the optimal formulation fertilization model is reasonable which has some practical guidance for the field cultivation of C. Sarcodactylis Fructus.

Streptomyces acidiscabies (SA), Ralstonia solanacearum (RS) and Erwinia carotovora subsp carotovora borgey (ECCB) cause plant scab, brucellosis and soft rot of carrot, respectively. These are common and prevalent bacterial disease in crop production. The volatile oil of Guava leaves consists of a variety of active substances with broad-spectrum anti-microbial activity. The aim of this study was to extract and configure an antimicrobial solution of guava leaves volatile oil to conduct a volatile oil resistance study against three disease bacteria, SA, RS and ECCB, to reserve resources for biological control agents. The volatile oil of guava leaves was extracted by the addition of lithium salt combined with microwave-assisted hydrodistillation, the antibacterial effect of guava leaf volatile oil on three test strains was evaluated by the filter paper diffusion method and minimum inhibitory concentration (MIC), and the extraction process was optimized by single factor combined with response surface experiments. The chemical components of guava leaf volatile oil were determined by gas chromatography-mass spectrometry (GC-MS). The results showed that the oil exhibited excellent inhibitory effects against SA, RS and ECCB, with the inhibition circle diameters ranging from 20.57 to 23.24 mm and the inhibition rates reaching more than 60%, and the MIC values of 3.13 μg/mL, 1.56 μg/mL and 3.13 μg/mL, respectively. The oil had the greatest inhibitory effect on RS, the diameter of the inhibition circle was (23.24±0.47)mm, which was highly sensitive, and also had certain inhibitory effect on SA and ECCB. The optimum process conditions for the extraction process were liquid to material ratio of 10 mL/g DW, microwave power of 660 W and microwave time of 43 min. The yield of the oil obtained under the conditions was (10.23±0.17)mL/kg DW, and the validity and reproducibility of the method were verified by three parallel experiments. The components of the oil were detected to be mainly terpenes and alcohols, with relatively high content of β-caryophyllene (28.36%), l-calamenene (11.47%), (-)-globulol (11.31%) and α-pinene (10.01%). The substances that played a major role in the antibacterial experiment were β-caryophyllene, α-pinene, eugenol, and D-limonene. It was speculated that the mechanism of guava leaf volatile oil inhibition on the test strain was the damage to its cell structure, which resulting in the leakage of intracellular material. The above results demonstrated that the guava leaf volatile oil has an excellent antimicrobial activity and considerable extraction rate, the results of the study would provide a reference for the development and application of guava leaves and integrated control of crop diseases.

To investigate the effects of different coating treatments on the quality of betel nut fresh fruits during storage, three groups of coating agents, aseptic distilled water (CK), chitosan (T₁), and chitosan-chitosan-thymol (T₂), were used to coat the surface of betel nut fresh fruits and then packed in PE bags with perforations to determine the quality changes of fresh fruits stored at 13℃ and 65% relative humidity for 40 days. The results showed that the T₁ and T₂ film treatments effectively delayed and inhibited fruit decay and softening, kernel browning, yellowing, water loss and shrinkage, and extended the shelf life from 5 days to 35 days. Compared with the CK group, the T₁ treatment effectively inhibited fruit yellowing, but the T₂ treatment had the best overall preservation effect, which not only enhanced the initial antioxidant capacity of fresh fruits, but also significantly inhibited the increase of weight loss and decay rate, and the decay rate was only 8% at the 35th day. At the same time, the color of fresh fruits was more stable and the browning of kernels was not obvious in T₂ treatment. In addition, the changes of respiratory intensity, hardness, cellulose and lignin content had showed that the T₂ coating treatment could maintain the physiological and metabolic capacity of fresh fruits during the storage period after 25 days, and the freshness preservation effect was significantly better than that of the CK group, so the T₂ coating treatment can be used as a green, safe, economic and effective method to preserve fresh fruits of betel nut.

The elucidation of cucurbitacin biosynthesis pathway is essential for heterologous production due to its significant anticancer activity. The biosynthesis of cucurbitacin starts from cucurbitadienol (Cuol) catalyzed by cucurbitadienol synthase (CBS) of the oxysqualene cyclase (OSCs) family to form 2,3-oxysqualene which subsequently catalyzed by cytochrome P450 (CYP) and other enzymes for oxidative modification to produce various cucurbitacins. In this study, an efficient transient expression system mediated by Agrobacterium tumefaciens was established. The CBS gene (HcOSC6) from Hemsleya chinensis and truncated 3-hydroxy-3-methyl-glutaryl coenzyme A reductase gene (tHMGR) from Avena strigose were continuously optimized in the tobacco co-expression system to increase Cuol yield from 2.832 mg/g (DW) to 9.48 mg/g (DW) in Nicotiana benthamiana leaves. Meanwhile, HcCYP87D20 of H. chinensis was also co-infiltrated into tobacco leaves to obtain 11-carbonyl-20β-hydroxy-cucurbitol. This study would provide a theoretical basis for efficient heterologous production of cucurbitacin.

Pteris minor is one of the rare pteridophytes in the coastal zone. Because its morphology is similar to that of P. fauriei, it has been wrongly identified as P. fauriei for a long time and lacks attention. In fact, there are obvious differences between them in habitat, plant morphology, spore morphology and chromosome ploidy. Therefore, P. minor was upgraded from a variety of P. fauriei to a species. In order to clarify the distribution area and survival status of P. minor, ArcGIS 10.7 software was used to construct the geographical distribution information maps of different geographical ranges of P. minor, by sorting out the previous collection records and research results, combined with the findings of the authors' field investigation, and its protection value was evaluated according to the standard of IUCN 3.1. The results show that: (1) In terms of the world geographical distribution pattern, P. minor is mainly distributed in Asia; In terms of the geographical distribution pattern in Asia, it is mainly distributed in China, Japan and Philippines; In terms of the geographical distribution pattern of China, it is mainly distributed in Zhejiang, Fujian, Macao, Hong Kong and Taiwan; In terms of the geographical distribution pattern of Japan, it is mainly distributed in the Ryukyu Islands; In terms of the geographical distribution pattern of Philippines, it is mainly distributed in the northern islands. (2) According to the IUCN 3.1 standard, the protection level of P. minor is temporarily set as near threatened (NT). According to the current data, the distribution range of P. minor is narrow, and its habitat is vulnerable to human activities, but it lacks protection for a long time. Therefore, corresponding protection suggestions were put forward finally.

In order to determine the quality of soil fertility of bamboo species in coastal sandy land and guide the construction and management of bamboo shelter forest in coastal sandy land, the difference of soil physical and chemical properties of different bamboo forests in coastal sandy land and evaluate the soil quality were studied. Eight bamboo species in coastal sandy land were selected from Chishan State-owned Farm in Dongshan County, Fujian Province. The physical and chemical properties of the 0-20 cm soil layer of each bamboo species were determined. One-way ANOVA analysis was conducted to test the significance of each index, and principal component analysis weighted comprehensive index method and fuzzy mathematics were used to comprehensively evaluate the soil fertility quality of different bamboo species. Soil moisture content, soil density, capillary porosity, non-capillary porosity and total soil porosity of Oligostachyum lubricum were significantly different from those of other bamboo forest (P<0.05). The average pH of soil ranged from 5.01 to 7.36, and there was no significant difference in the pH of other bamboo forests except the neutral soil pH of Bambusa oldhamii (P>0.05). The average soil organic from 4.43-11.06 g/kg, Pseudosasa amabilis var. convexa was significantly lower than that of other bamboo forests. The average range of soil total potassium and available potassium was 4.59-79.33 g/kg and 0.78-43.11 mg/kg. The average range of soil total nitrogen and total phosphorus was 0.47-2.42 g/kg and 0.09-0.37 g/kg, and soil electrical conductivity, total availability and quick availability of N, P, K. had significant differences among different bamboo forests (P<0.05). The order of soil fertility quality index order of the eight bamboo species was P. japonica>O. lubricum>Phyllostachys nidularia f. farcata>B. oldhamii>Dendrocalamus minor var. amoenus>B. tuldoides 'Swollenintrnode'>B. eutuldoides var. viridi-vittata>P. amabilis var. convexa. The physical and chemical properties and total soil quality of bamboo shelterbelt in coastal sandy land were significantly affected by the types of bamboo stands. P. japonica could effectively improve soil quality, but the effect of P. amabilis var. convexa. on soil improvement was not obvious. Bamboo species and planting methods should be selected rationally for the construction and management of bamboo shelterbelt in coastal sandy land.