Cassava is an important food crop, energy crop and industrial raw material. Cassava mealybug (Phenacoccus manihoti Matile-Ferrero) is a dangerous quarantine pest in the world, the cultivation and utilization of insect-resistant cassava cultivars can effectively block its colonization. Mining insect-resistant secondary metabolites and the regulatory genes is one of the important strategies for insect-resistant breeding. Flavonoids are unique secondary metabolites for plants to resist biotic and abiotic stresses, but the function of flavonoids and the synthesis pathway genes in cassava resistance to cassava mealybug is still unclear. Based on this, this study analyzed the expression levels of flavonoid synthesis pathway-related genes (CHS, CHI, FLS, LAR, DFR, F3H, CCoAOMT, C4H, C3'H and ANR) and flavonoid content in the leaves of insect-resistant (C1115, SC9, Myanmar) and insect-susceptible (KU50, SC205 and Bread) cassava cultivars after being damaged by cassava mealybug for different time (0, 1, 4, 8 d). Although the expression of CCoAOMT, C3'H, ANR and C4H in the leaf was up-regulated after feeding, there was no significant difference compared with that before damage, and there was no significant difference in the expression level between the resistant and susceptible cassava cultivars. In contrast, the expression levels of CHS, CHI, FLS, F3H, DFR and LAR genes were significantly higher than those before damage, and in the same damage time, the expression levels of the six genes in the insect-resistant cassava cultivars were also significantly higher than those in the insect-susceptible cassava cultivars. Further correlation analysis showed that the expression levels of CHS, CHI, FLS, F3H and LAR genes were significantly positively correlated with the insect resistance of cassava cultivars. In addition, the results of total flavonoid content determination showed that the total flavonoid content increased significantly after one day of damage compared with that before damage, and the total flavonoid content of insect-resistant cassava cultivars was significantly higher than that of the insect-susceptible cassava cultivars after 4 days of damage. Correlation analysis showed that the total flavonoid content was also significantly positively correlated with the insect resistance of cassava cultivars. Therefore, it is speculated that the increase of flavonoid content and the significantly up-regulation of CHS, CHI, FLS, F3H and LAR in the insect-resistant cassava cultivars may be related to the resistance to cassava mealybug. This study would provide an important preliminary basis for the in-depth analysis of the molecular mechanism of flavonoid synthesis genes regulating the insect-resistant defense response of cassava to mealybug, as well as the molecular design and breeding of cassava insect-resistant.

Cell wall degrading enzymes are important pathogenic factors of many pathogenic fungi, among which xylanase, as the most important hemicellulase, plays an important role in the process of host cell wall degrading by filamentous fungi to achieve host infection. In this study, RT-PCR was used to clone the coding region of xylanase GpTR1774 gene of Ganoderma pseudoferreum strain HD3 and analyze its bioinformatics. The root of Hevea tissue cultured seedlings Reyan 73397 were infected with HD3, meanwhile infection and destruction process of root cells were observed by electron microscopy. The gene expression of GpTR1774 was determined by qRT-PCR. The results showed that the total length of GpTR1774 cDNA was 780 bp, encoding 259 amino acids, among which the most abundant amino acid was alanine (Ala), accounting for 15.1%. The molecular weight of GpTR1774 protein was 28.12 kDa, fat coefficient was 81.93, and the isoelectric point was 9.07. It was a hydrophilic protein with 15 phosphorylation sites, no signal and peptide transmembrane domain, and was located in the cell solute. The main components of the secondary structureα-helix and random curling are the main components of the secondary structure of GpTR1774 protein, accounting for 38.10% and 41.31% of the amino acid sequence, respectively. Phylogenetic analysis showed that GpTR1774 gene had the highest similarity with xylanase gene of Ganoderma boninense, reaching 87.5%. qRT-PCR showed that the overall gene expression trend of xylanase GpTR1774 was firstly increased and then decreased. The expression level of GPTR1774 increased significantly on the 3rd and 4th day after infection, and reached the highest level on the 4th day, about 16 times of the initial level. The results of this study indicate that the xylanase GpTR1774 gene was likely to be involved in the pathogenesis of G. psedoferreum, providing reference for the pathogenesis analysis and green prevention and control of G. psedoferreum.

Polysaccharide is a quality marker of Polygonatum odoratum, which has significant pharmacological effects in immune regulation and anti-tumor. As one of the key enzymes in polysaccharide synthesis, sucrosesynthase (SUS) has always been an important research field to reveal the synthesis of plant polysaccharides. Based on transcriptom data of Polygonatum odoratum, the SUS gene family members were identified by bioinformatics, and their expression profiling were analyzed using qPCR. The results showed that eight PoSUS gene were identified, their protein ranged from 111 to 310 amino acid residues (aa) in length, and relative molecular weight varied from 12.81 kDa to 35.43 kDa, isoelectric point (pI) in the range of 5.83 to 9.18; phylogenetic analysis indicated that eight PoSUS genes were divided into 3 subfamily, and the subfamily Ⅲ included the largest PoSUS genes family member; subcellural localization analysis showed that most of PoSUS proteins were located in chloroplast. Additionally, expression patterns analysis revealed that PoSUS1 and PoSUS6 genes were preferably expressed in rhizome, and the transcript levels of PoSUS1 and PoSUS2 were higher in high-polysaccharide cultivar HN1 than those in a low-polysaccharide cultivar AH2. In addition, the CDS of PoSUS1 gene were cloned from HN1 and AH2, there are three amino acid difference between HN1 and AH2, which located in sucrose synthase domain. Our findings can laid a basis for the further study of functional analysis of SUS genes, and provided a theoretical basis for analyzing molecular mechanism of the formation mechanism of medicinal quality of Polygonatum odoratum.

GATA transcription factors play an important role in regulating plant response to abiotic stress. In this study, an IbGATA16 gene was cloned from sweet potato and analyzed by bioinformatics. The expression pattern of IbGATA16 gene in sweet potato under drought and salt stress was analyzed. Experimental results show that the full length of IbGATA16 CDS sequence is 420 bp, and it encodes 139 amino acids. The molecular weight of IbGATA16 was 15.39 kDa, isoelectric point was 9.97. The full length of the genome is 582 bp, including 3 exons and 2 introns. IbGATA16 is an unstable hydrophilic lipid-soluble protein., and its subcellular localization predicts that the protein is located in the nucleus. It has the C-X₂-C-X₁₇-C-X₂-C domain and belongs to the typical GATA class of transcription factors. There are many cis-acting elements in the 1382 bp upstream promoter sequence of IbGATA16 gene, such as MYB, ABRE, and GARE-motif. The results of multiple sequence alignment and phylogenetic tree analysis showed that IbGATA16 protein was closely related to ItGATA16. The sequence of the N-terminal zinc finger domain is highly consistent, suggesting a possible similar function. The results of real-time fluorescence quantification showed that IbGATA16 was expressed in root, stem and leaf tissues of sweet potato, and the expression level of IbGATA16 in leaves was significantly higher than that in stem and root tissues. IbGATA16 was significantly induced by drought and salt stress, and after 0, 1, 3, 6, 12 and 24 h of drought and salt stress, the expression of IbGATA16 was significantly higher than that of 0 h. Under drought stress, the expression of IbGATA16 reached its peak at 1 h, and under salt stress, the expression of IbGATA16 reached the maximum at 3 h. IbGATA16 positively responds to drought and salt stress in sweet potato. These results indicated that IbGATA16 gene was involved in the response of sweet potato to drought and salt stress, and the regulation of IbGATA16 gene was different in roots, stems and leaves. This study provides a reference for further research on the biological function of IbGATA16 and its mechanism in response to stress in sweet potato.

In order to understand the diversity of phenotypic traits in F₁ segregation populations of date palm, this study used 143 F₁ segregation populations of date palms as test materials to analyze the diversity, correlation, principal component and cluster analysis of 17 phenotypic traits, including plant height, crown breadth, stem girth, number of branches and leaf spot incidence. The results showed that there was a high degree of phenotypic variation and rich diversity in F₁ segregation population of date palms. The variation degree of quantitative characters was high, the coefficient of variation ranged from 10.927% to 43.350%, and the coefficient of variation of stem girth was the largest. The coefficients of variation of quality traits ranged from 31.447% to 44.619%, among which the coefficients of variation of tiller leaf color and leaf hardness were 44.619% and 42.571%, respectively. The correlation analysis showed that plant height, crown breadth, stem girth, number of branches, the third branch of long, the thorn area length, the total number of tiller leaves, tiller leaves length, tiller leaves width, tiller leaf thickness and leaf color were positively correlated with each other. The incidence of leaf spot was negatively correlated with the other 16 traits. The principal component analysis showed that the cumulative contribution rate of the six principal components reached 87.51%, of which the characteristic value of the first principal component was 10.0836, and the contribution rate was 59.32%. It is mainly affected by the five indicators of plant height, third branch length, crown breadth, stem girth and branch number. The characteristic value of plant height is the largest, which is 0.2948, which mainly reflects the height and growth trend of date palm. The cluster analysis showed that the 143 F₁ generation dates could be divided into five groups: Group Ⅰ included 33 dates with the smallest crown, the least number of branches, the shortest tiller leaves length, and the highest incidence of leaf spot disease. Group Ⅱ included 39 dates resources with the shortest plant height, the smallest stem girth, the shortest third branch length, and the heaviest incidence of leaf spot disease. Group Ⅲ included 23 dates resources with longer tiller leaves, darker tiller leaves, erect plant type and mild incidence of leaf spot disease. Group Ⅳ included 33 dates resources with excellent phenotypic traits such as large ratio of leaf length to width of tiller leaves, stiffer tiller leaves and the least incidence of leaf spot disease. Group Ⅴ included 14 dates resources with small ratio of tiller leaves length to width ratio and open plant type. The results of this study can provide a theoretical basis for the breeding of superior parental traits in later stage of date palm.

Anoectochilus roburghii is a rare and endangered medicinal orchid with high economic value. High temperature is the primary limiting factor for its extensive production and cultivation. Breeding heat-resistant varieties is one of the most economical and effective measures to resist heat damage caused by high temperature. In this study, we analyzed the genetic diversity of 24 A. roburghii germplasm resources by Start codon targeted polymorphism (SCoT) molecular markers, and evaluated the heat tolerance of 20 samples by multivariate statistical analysis. The results of genetic diversity analysis showed that at the genetic coefficient was 0.602, A. roburghii germplasm could be divided into two groups: I and II, Group I was divided into two subgroups A and B, Anoectochilus formosanus was classifiedd into Group II alone. In subgroup A, except W from Yunnan, all the other resources were collected in the north and west of Fujian. Subgroup B mainly came from Southern Fujian and Guangxi. The cluster diagram showed that the relatives of A. roburghii from the same origin was close, and the presence or absence of reticulated veins was not the basis for the classification. Five physiological parameters were measured in the 20 samples. It was found that the chlorophyll content and SOD activity decreased obviously after heat treatment, and the relative conductance increased obviously, while the malondialdehyde and soluble protein contents of each resource were different after heat treatment. The preliminary evaluation of heat resistance was conducted by the multivariate statistical analysis method, and the results showed that four resources (TL, L1, A20, GZ1) were heat resistant, while five resources (TJ, HX, L, M, A21) were not.

The study of source/sink relationship has important theoretical research and technical application value in crop yield and quality formation. With the interdisciplinary integration of crop genetics and breeding, plant physiology and molecular biology, the study of source-sink relationship has made important progress in recent years by integrating molecular biology techniques, plant hormone signal transduction and many other new technologies and methods. In this paper, the research progress is reviewed from two aspects: source/sink relationship theory and regulation. The mechanism of glucose metabolism and hormone regulating source/sink relationship was emphasized, and the mechanism of cultivation measures improving yield by coordinating source/sink relationship was analyzed. Combined with the research progress on the mechanism and regulation of rubber trees, an important tropical cash crop. This lay a foundation for the theory of source/sink relationship in natural rubber industry and provide technical guidance for the creation of rubber latex flow control technology.

Watercore is a kind of physiological disease of pineapple fruit, which causes the intercellular space of pineapple pulp tissue to be filled with cell fluid and appear as water-soaked, which seriously affects the edible value and commercial value of the fruit. Watercore has troubled the development of pineapple industry for many years, but its mechanism is not clear. In order to explore the pathogenesis of watercore in pineapple, this study took the main pineapple cultivar Comte de paris as the material, the paraffin section method was used to observe the process of watercore in pineapple fruit and the different tissue parts of normal and watercore fruit (flower stock, carpel, fruit sequence axis). The results showed that the cell structure of pineapple pulp was closely related to watercore: the cell structure of normal fruit pulp was complete, the cell space was obvious, the vascular bundle was intact, the phloem cells were arranged tightly and neatly, and the xylem ducts were arranged regularly. However, fruit flesh cells in watercore are squeezed and deformed, and the cell wall rupture results in incomplete cell structure, destruction of vascular bundle morphology, extrusion and deformation of phloem, and destruction of xylem ducts to form a cavity. With the deepening of the onset process of watercore, the xylem cavity becomes larger. Through the morphological observation of different tissue parts of normal fruits and fruit with watercore, it was found that the changes of cell structure caused by watercore in different tissue parts were basically the same. There were obvious differences in vascular bundle morphology and structure in different tissue parts. The vascular bundles in the fruit sequence axis and receptacle were in accordance with the typical characteristics of vascular bundles in monocotyledons. The vascular bundles were surrounded by a sheath composed of thick-walled mechanical tissue at the periphery of each vascular bundle. On the other hand, there were more sachmatous cells at both ends of the vascular bundle. The inner part of the vascular bundle sheath contains primary phloem and primary xylem without the middle bundle cambium. The vascular bundle structure of the carpel was atypical, and most of the vascular bundles were not surrounded by vascular sheath. Vascular tissues in the fruit sequence axis were the most developed, followed by receptacle, and vascular tissues in the carpel were the least developed. These results revealed the morphological changes of pineapple watercore during its occurrence and provided reference for further research on the mechanism of watercore.

The problem of soil salinization in my country is becoming more and more serious. Rice is the preferred food crop for the improvement of salinized land, but salt stress is one of the main abiotic stresses that influence the growth and yield of rice. In order to fully understand the effect of salt stress on the rice, 31 varieties (lines) of tropical rice with different salt tolerance were used as experimental materials, and experiments were carried out by hydroponics in seedling stage incubator and potted soil cultivation method in the whole growth period, to study the effects of 0 NaCl (CK), 0.3% NaCl and 0.6% NaCl on the growth, physiological and biochemical characteristics, and yield composition of tropical rice. The result showed that: (1) The seedlings and roots growth of tropical rice were inhibited under salt stress. The seedling height and root number were significantly decreased with the increase of NaCl concentration, the root length in 0.3% NaCl and 0.6% NaCl treatments was significantly lower than CK treatments; and the fresh weight of seedling in 0.6% NaCl treatments was significantly lower than CK and 0.3% NaCl treatments. (2) Chlorophyll accumulation of tropical rice leaves were decreased under salt stress. The contents of chlorophyll a, chlorophyll b and Car in the treatments with 0.3% NaCl and 0.6% NaCl concentrations were significantly lower than CK treatments. The accumulation of proline (Pro), malondialdehyde (MDA) and Na⁺ were increased. The content of Pro and MDA and Na⁺ in the treatments with 0.6% NaCl concentration were significantly higher than treatments with CK and 0.3% NaCl concentration. The accumulation of K⁺were decreased. The K⁺ content in the 0.3% NaCl and 0.6% NaCl concentration treatments was significantly lower than the CK concentration treatments. (3) Under salt stress, the tiller number, panicle number, panicle length, panicle grain number, thousand-kernel weight and yield of per plant were significantly decreased with the increase of NaCl concentration.

To study the differences in the physical and chemical properties of biochar obtained from three legumes at different temperatures, and to determine the appropriate temperature range for legume biochar. Using leguminous plant peanut straw, soybean straw and stylofoam as raw materials, peanut straw biochar (Pe), soybean straw biochar (Be) and stylofoam biochar (St) were prepared at 300 ℃, 500 ℃ and 700 ℃. A Fourier infrared spectrometer was used to qualitatively analyze the functional groups on the surface of the biochar, and the surface morphology of the biochar was observed with a scanning electron microscope, and the physical and chemical properties, such as pH, C and N content, were measured. The results showed that the carbon content of biochar prepared from three kinds of raw materials increased with the increase of pyrolysis temperature at 300 ℃ to 500 ℃, and was basically stable after 500 ℃; the nitrogen content and yield of biochar decreased with the increase of temperature. Among the biomass charcoal prepared from the three materials, Be has the highest carbon content and C/N, and N content and yield are the lowest. The ash content, ash alkalinity and pH of biochar all increase with the increase of pyrolysis temperature. The same pyrolysis ash alkalinity and pH of biochar all increase with the increase of pyrolysis temperature. The same pyrolysis temperature and different materials are all expressed as Be>St>Pe. Both the pore size and specific surface area of biochar increase with increasing temperature. The three raw materials of biochar form more stable aromatic compounds with increasing temperature, and the structure is mainly C=O and C=C. In this study, the suitable pyrolysis temperature of legume biochar is 500 ℃, and the temperature rises again, which has little effect on the physical and chemical properties of biochar. In summary, the soybean biochar produced by cracking at 500 ℃ is more used in farmland soil improvement, and can also try soil remediation, carbon sequestration and emission reduction applications.