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.

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.

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.

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..

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.

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.

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.

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.

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.