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.

Cassava (Manihot esculenta Crantz) is the sixth-largest food crop in the world, nearly 700 million people in the world tropical regions take it as the primary food source, and it is also an important raw material for the production of starch, modified starch, fuel ethanol and other chemical products and feed in China. It plays an important role in eradicating hunger, poverty alleviation and rural revitalization in tropical areas. Cassava root is rich in starch, which can provide energy for livestock and poultry growth. Cassava stems and leaves are rich in protein, cellulose and vitamins and other nutrients, thereby becoming a high-quality protein feed resource. Energy value of cassava is similar to that of corn, thus boasting great development potential as the feed. In recent years, it has achieved good results in the breeding of livestock and poultry such as pigs, sheep and chickens. Therefore, it is of great significance of using cassava as energy feed and replacing corn and other raw materials to mitigating competition for food between human beings and livestock and improve the economic benefits of breeding. This article comprehensively analyzed the nutritional value of cassava and the research progress of its feed application, and put forward specific suggestions for further research and utilization to provide reference for the development of cassava feed industry in the future.

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.

Cassava leaves are rich in abundant flavonols, and efficient extraction and analysis methods are crucial for the evaluation of flavonol content in the cassava leaves. This study aims to optimize the extraction and detection methods for four flavonols (myricetin, rutin, nicotiflorin, narcissoside) in cassava leaves and to analyze the influence of different cassava varieties, harvesting periods, and maturity on the content of these flavonols. The results indicated that using a 50% ethanol-water solution, a liquid-to-material ratio of 1∶50 (g/mL), an ultrasonic extraction temperature of 50 ℃, and an ultrasonic extraction time of 60 minutes could effectively extract the four flavonols in the cassava leaves. The combination of different C18 chromatographic columns in HPLC-DAD effectively separated the four flavonoids present in the cassava leaves. The results of the method validation showed that the four flavonols exhibited good linear correlations within a certain concentration range, with R² values of 0.9999, 0.9999, 0.9999 and 0.9998, respectively. The detection limits ranged from 6.0 mg/kg to 10.0 mg/kg, and the quantification limits ranged from 20.0 mg/kg to 32.0 mg/kg. The detection method demonstrates good system adaptability, with retention time and peak area relative standard deviations (RSD) being less than 1%. The samples showed good stability in terms of intra-day, inter-day, and intra-month variations, with RSD in content variations ranging from 0.44% to 3.57%. The average recovery rates of the method ranged from 92.68% to 109.14%, all with RSD values less than 6.0%. Utilizing the established extraction and analysis methods, the study analyzed the content of the four flavonols in 30 cassava germplasm resources. Rutin and nicotiflorin maked up 93.50% to 99.30% of the total flavonol content in the cassava leaves, with the levels primarily determining the total flavonol content. However, the correlation order for the total flavonol content among different varieties was rutin>narcissoside>nicotiflorin>myricetin. Analysis of flavonol content in the cassava leaves from different harvest times and maturity levels of cassava germplasm revealed that in most cases, the levels of rutin, nicotiflorin and narcissoside were higher in the leaves harvested at 270 days compared to those harvested at 180 days, with myricetin varying by variety. Except for SC09, the levels of myricetin, rutin and nicotiflorin were higher in the young leaves compared to the tender and mature leaves in different cassava germplasms. The content of narcissoside in mature leaves (except for flower leaf cassava) was higher than that in young leaves and tender leaves. The results would provide an evaluation basis for the development and utilization of cassava flavonols in the selection of raw materials and quality control, and lay a foundation for revealing the accumulation rules of cassava flavonols.

The flavonoid quercetin is one of the main active ingredients in Chinese medicinal herb, Euphorbia maculata. At present, there are few reports on quercetin biosynthesis gene, and real-time quantitative PCR (RT-qPCR) is one of the common methods in gene research. But it is a prerequisite for relative quantitative RT-qPCR to have suitable reference genes. In order to obtain a suitable reference gene, this experiment was based on the results of transcriptome sequencing, EmSE, EmUBC, EmGDI1, EmLSM12, EmGBP, EmSYP22, EmTRI1, EmRSZ21, EmRPL7 and EmUBQ obtained by our research group in the early stage were selected as candidate reference genes. RT-qPCR was used to detect the expression of the candidate reference genes in roots, stems, leaves and fruits of E. maculata during vegetative and reproduction stages. The expression stability of the candidate genes was analyzed using geNorm, NormFinder and BestKeeper software. The results of different software were integrated and ranked by the geometric mean method. The ranking was in the order EmGDI1>EmUBQ>EmSE>EmUBC>EmLSM12=EmGBP>EmTRI1>EmSYP22>EmRSZ21=EmRPL7. EmC4H, a key enzyme gene in quercetin biosynthesis, was analyzed using EmGDI1 as the reference gene. The difference of EmC4H expression in different tissues at different stages was consistent with the trend of transcriptome sequencing. The reference gene EmGDI1 developed in this study could be used as a suitable reference gene for tissue-specific expression studies of different stages of E. maculata.

In order to deepen the understanding of the tolerance of Excoecaria cochinchinensis, Nerium oleander and Fagraea ceilanica to intermittent flooding and high concentration of ammonia nitrogen, an intermittent flooding cultivation experiment was conducted with six aqueous solutions of ammonia nitrogen concentration (0, 0.5, 7.5, 14.5, 21.5, 28.5 mg/L). After 90 days of continuous test, the morphological and physiological indexes of the three plants were determined, aimed to provide theoretical references for the application of the three plants in rain garden, subsurface flow wetland, intermittent flooded green space and other environments. The results showed that: (1) Compared with the soil culture control, under intermittent flooding, all three plants showed adaptive changes in enhancing oxygen delivery to the roots, such as enlarged stem base lenticels and adventitious root formation, and significantly promoted the height growth of N. oleander. However, the growth rate of E. cochinchinensis and F. ceilanica was slowed down due to the influence of flooding; (2) Under the interaction of intermittent flooding and ammonia nitrogen, the plant height of N. oleander increased with the increase of ammonia nitrogen concentration, while the plant height growth of E. cochinchinensis and F. ceilanica was significantly inhibited after the ammonia nitrogen reaching 14.5 mg/L, and when the ammonia nitrogen was 21.5 mg/L, the leaves of E. cochinchinensis appeared symptoms such as reduced leaf area and green loss; (3) Intermittent flooding had no significant effect on the activities of antioxidant enzymes and the contents of chlorophyll, malondialdehyde (MDA), free proline (Pro) and soluble protein (SP) of the three plants. On the 60th days, the activities of antioxidant enzymes, free proline and soluble protein of the three plants fluctuated to some extent, but on the 90th day, each index had little difference compared with soil culture; (4) Under the interaction of intermittent flooding and ammonia nitrogen, on the 90th day, N. oleander could recover to the normal level even when the ammonia nitrogen was 28.5 mg/L. After the ammonia nitrogen was 14.5 mg/L, E. cochinchinensis and F. ceilanica tended to produce more antioxidant enzymes, MDA and free proline, less soluble protein, with obvious physiological disorders. It could be seen that N. oleander showed active morphological adaptation and strong resistance in the aqueous solution with ammonia nitrogen concentration of 0-28.5 mg/L, and could grow in a certain length of time and intermittent flooding environment. Although E. cochinchinensis and F. ceilanica also showed strong adaptability, the tolerance to ammonia nitrogen was weaker than that of N. oleander, and they only grew well in the range of 0-14.5 mg/L ammonia nitrogen concentration aqueous solution. Therefore, the three plants could be used in the intermittent flooded green space, and N. oleander has strong adaptability to high concentration ammonia nitrogen water environment.

The molecular mechanism of the formation of flower diversity is still unclear. In this study, the transcriptome and microRNA sequencing of Dendrobium officinale and D. loddigesii flower organs were performed, and the miRNA-mRNA network and target protein interaction network were constructed by cytoscape and compared at the molecular level. The results of transcriptome studies showed that mRNAs related to flower development had MADS-box AP3 gene, hormone genes, etc. The miRNA-mRNA network analysis showed that the differentially expressed miRNAs and mRNAs were involved in the differential formation of floral pattern, and miR5179 and its target genes AP3, miR160 and their target genes ARFs, miR164 and its target genes NAC021, miR159 and the target genes GAM1, bdi-miR159 and the target genes CKX9, miR167b-3p and the target genes ANT may be involved in floral pattern formation, and the above miRNA was upregulated in D. officinale. The protein interaction pathway showed that two kinds of dendrobium had the key gene of AP3, D. loddigesii lacked four genes: CUL1, TIR1, TIR1A and RBS; there weret wo differentially expressed ARFs genes in the auxin response interaction pathway of two Dendrobium, and D. loddigesii lacked one ARFI gene; D. loddigesii flora specifically possessed the protein interaction pathway of auxin signal transduction target genes constituted by the NAC021 gene. Differential expression of miRNAs/mRNAs in D. officinale and D. loddigesii and protein interaction of target genes may be the main mechanisms leading to the difference between the two Dendrobium flower types.

Abundant germplasm resources are the basis for mango variety breeding and industrial development. For better protection and utilization of mango germplasm resources, the TP-M13-SSR marker developed by our team previously were used to analyze the genetic diversity and construct molecular ID of 145 mango germplasms containing local cultivars, bred varieties and wild relative species, which stored in the nursery of Guangxi Innovation Base of mango germplasm resources conservation. The results showed that the average number of observed alleles for the 12 primer pairs was 3.2838, the average observed heterozygosity (H_o) was 0.5858, the average expected heterozygosity (H_e) was 0.6725, the average Shannon index (I) was 1.3383, and the average Nei's gene diversity index (N_a) was 0.6702. The polymorphism information content (PIC) of the 12 primer pairs ranged from 0.5036 to 0.7827, with an average value of 0.6396. All the primers were highly polymorphic sites. The result suggested that TP-M13-SSR primer could provide data support for genetic diversity analysis of mango. The genetic similarity coefficient of 145 materrials varied from 0.5676 to 1.000, with an average of 0.7417. The genetic similarity coefficient between Irwin and Indian No. 1 was 1.000. The minimum genetic similarity coefficient was 0.5676, between M. persiciformis 20-2 and Dadouxiang mango, M. persiciformis 20-2 and Shuoshuai mango, Jinhuang mango and Guire 10-1 mango. All the 145 mango germplasms were divided into two groups when the genetic similarity coefficient was 0.7060. Group I contained 108 mango species and 20 M. persiciformis species, accounting for 88.90% of the total number of germplasms. Group Ⅱ contained 17 specimens, all of which were M. persiciformis species. Group I could be further divided into five subgroups when the genetic similarity coefficient was 0.7330, among which subgroups I-1 and I-3 were the most abundant, accounting for 91.92% of all mango germplasms. The results of UPGMA clustering analysis showed that M. persiciformis were not clustered strictly according to the species relationship, and the overall clustering result of mango germplasms was basically consistent with its geographical origin. All the 145 materials were amplified by 12 pairs of SSR fluorescent primers to obtain the fingerprint map, and the molecular ID was obtained by the assignment of numbers and letters combination. Each pair of primers could distinguish 12.4 germplasms on average, and the identification rate was significantly higher than that of previous studies, indicating that TP-M13-SSR had more advantageous than denaturing polyacrylamide gel electrophoresis in mango germplasm identification. This study would provide scientific basis for the collection and utilization of germplasm resources and variety breeding of mango. It is also proposed for molecular identification of bred varieties, which is of great significance to the development of mango industry for providing methods for molecular identification and intellectual property of bred varieties.

Phalaenopsis has a rich variety of flower colors, a long-lasting flowering period, a unique flower type, and high ornamental value. It is considered the most popular and commercially valuable orchid in the market. The axillary buds at the base of each leaf of Phalaenopsis orchid can form pedicels, but most of the axillary buds are in a dormant state during the flowering period. Studying the germination law of latent axillary buds can help improving the proportion of multiple flower stalks in Phalaenopsis, and has good application prospects. The main environmental factors (temperature, plant hormones, light environment, nutrient accumulation, etc) affecting the germination of Phalaenopsis bud and the regulatory methods to promote flower bud germination will be reviewed, in order to provide a reference for the application of regulating more flower bud germination in Phalaenopsis industry in the future.

In this study, the effects of different concentration and ratio of growth regulators on seed germination, rapid propagation and in vitro flowering of Mengzia foliosa were studied. The results showed that the seeds had strong activity and high germination rate at 105 days after artificial self-pollination, and 1/2MS+0.6 mg/L NAA+1.0 mg/L 6-BA medium was more suitable for seed germination. Meanwhile, 2.0 mL/L 6-BA without NAA was more suitable for cluster bud proliferation; and 1/2MS+1.0 mL/L NAA+30 g/L potato homogenate medium was the best for rooting and hardening-off. In addition, 1.0 mg/L 6-BA+0.5 mg/L NAA+1.0 mg/L PP₃₃₃ medium had the highest flowering rate. Our results not only contribute to the conservation and sustainable use of the species, but also provide important materials and technical support for wild population restoration and reconstruction.