In order to screen healthy and excellent introduced sugarcane germplasm, enrich sugarcane hybrid parent resources and obtain excellent sugarcane varieties with direct popularization and application value, 41 foreign sugarcane germplasm materials from France, United States, Barbados, Belize, Jamaica, Romania, Guyana and other countries introduced through Visacane, CIRAD, France, responsible for introduction, export and quarantine of sugarcane germplasm from different countries, were planted in quarantine house for two sugarcane growth cycles. During the period, the quarantine disease such as sugarcane white stripe disease, Fiji disease and gummosis disease were monitored. After qualified quarantine, the natural disease occurrence, agronomic traits, cane yield and sugar content were investigated in field experiment. The 41 introduced foreign sugarcane germplasm entries had quarantine diseases and pests. In the field natural disease test, there were nine sugarcane germplasms B03-224, B03-876, FG08-057, FG08-757, FG09-128, FG09-331, FG09-367, FG09-538 and FR89-746 with good disease resistance, which could be used as disease resistant parents. Eight high sugar germplasms with high sugar content, B03-224, BBZ88-343, BJ99-32, BR08-004, CP04-1844, CP05-1526, FG06-691 and FG09-367, were evaluated as 1 grade, which could be used as high sugar parent. Five high-yield germplasms with high yield, BZ93-855, CP00-1446, FG09-124, FG09-346 and FR90-881, were evaluated as grade 1 and could be used as high-yield parents. Eleven germplasms, B03-224, BBZ93-855, BJ99-106, CP00-1446, CP05-1526, FG04-333, FG06-691, FG07-338, FG09-124, FG09-128 and FG09-367, with high-yield and excellent agronomic characters, entered the next round of comparative test to continue screening. In order to select sugarcane germplasms with high yield, high sugar and disease resistance that can adapt to the ecological environment of Guangxi for direct planting, four with excellent comprehensive performance, B03-224, FG09-128, FG09-367 and CP05-1526, were selected for the further variety comparison test. All sugarcane germplasms were kept in Nanning Sugarcane Germplasm Resources Nursery and Sanya Sugarcane Cross Breeding Base of Guangxi Academy of Agricultural Sciences for further evaluation of drought resistance, cold resistance, and subsequent cross utilization. This study could provide reference for the utilization of sugarcane germplasms introduced from abroad.

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).

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.

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.

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.

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.

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.

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.

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.