The islands are important pivots for the development of South China Sea, and which play an important role in ensuring the development sustainability of South China Sea and safeguarding national rights and territorial integrity. The islands in South China Sea have rich biodiversity and complex ecological functions, but they are also vulnerable to human disturbances. The paper summarizes the basic characteristics of the climate, water, soil, biology and agriculture development of the islands. It indicates that keeping ecological sustainability is the fundamental task during the development of islands, and it is important to reduce the disturbances of human factors on the islands ecology, and pay attention to the development of island agriculture and modern marine ranching, and build a comprehensive evaluation system for the ecology sustainable development of islands, that will ensure the realization of social, economic and national security services function of the South China Sea islands.

At present, the safety of natural rubber resources in China is becoming increasingly prominent. It is of great theoretical and practical significance to carry out dynamic monitoring of natural rubber production. Based on the long-panel data set, the spatial distribution characteristics, and evolution of natural rubber in China from 1995 to 2020 were studied by using production scale index, production concentration index, production gravity analysis method, efficiency advantage index, scale advantage index and aggregated advantage index in this paper. The results showed that the distribution of natural rubber production in China gradually concentrated to Yunnan and Hainan from 1995 to 2020, and the production concentration index of Yunnan and Hainan reached 97.87% in 2020. Yunnan surpassed Hainan to become the most comparative advantage rubber planting area in China, and Hainan belonged to the comparative advantage area. At the same time, the spatial center of gravity moved to the northwest obviously, and the comparative disadvantages of Guangdong, Guangxi and Fujian were more prominent. In the future, the spatial statistical analysis method based on multi-factor and multi-scale would become an important development direction of the research on the spatiotemporal evolution and prediction of natural rubber production distribution.

FRK1 is a marker gene downstream of the innate immunity in Arabidopsis thaliana (At), and FRKI's expression implies the initiation of the PTI pathway. This experiment screened eight FRK1-like genes from the cassava local genomic database via the Blastp method. Bioinformatics analysis reveals that all the eight FRK1-like genes encode receptor-like protein kinases with amino acid lengths between 804-921 aa and an average protein sequence length of 863 aa. The eight genes were found unevenly distributed on cassava chromosomes, mainly on chromosomes 11 and 4. The analysis of the gene structures showed that the eight genes could be classified into two groups, which in agreement with the results of the evolutionary tree analysis. Based on the location of the conserved motifs and the length of amino acid residues, it was found that MeFRK1, MeFRK4 and MeFRK5 shared three conserved motifs with AtFRK1, and the length of the conserved motifs was between 50 and 250 aa. By comparing with AtFRK1 and factoring in the results of protein motifs, chromosome positioning and evolutionary relationships, MeFRK1 was identified as a marker gene downstream of the innate immunity in the cassava genome. The experiment was conducted on cassava SC8 group-cultured seedlings, and the expression of MeFRK1 gene in leaves was measured by fluorescence quantitative PCR after treatment with the hormones SA, JA and the pathogenic bacteria Xam, respectively. The experiment unveiled that the expression of MeFRK1 gene after the treatment of hormones SA, JA and Xam all demonstrated an increasing trend followed by a decreasing one. After the treatment of the hormone SA and JA, the expression of MeFRK1 gene both peaked at 15 min, with the expression under SA treatment slightly higher than that of JA. While after the treatment of Xam, the expression peaked at 4 d at which time the expression was significantly higher than that of SA and JA treatments, 2.84 times that of the SA treatment and 3.06 times that of the JA treatment. It is evident that MeFRK1 has a positive regulatory effect in response to SA and JA signaling pathways for a short period of time, and the response is relatively rapid. Pathogenic Xam could better induce the expression of MeFRKI gene, thus improving the resistance of cassava to pathogenic bacteria Xam. The results may lay the foundation for further establishment of a molecular system for cassava disease resistance.

Three-line matching is the main research direction of pepper breeding, identification and development of restorer gene linkage markers in pepper is a difficult problem in restorer line breeding. In this study, the F₂ segregation population was constructed by using 014A and 014C as parents, the segregation ratio of fertility and sterility was 3∶1 by χ² test, indicating that CMS fertility recovery trait of capsicum was controlled by one pair of dominant genes. Using the BSA method to construct the mixed pool of fertile and sterile DNA, the whole genome was re-sequenced and compared with the reference genome, by SNP-index Method and Fisher Test, the cytoplasmic male sterility restorer gene was mapped in the region of 1.44-8.28 Mb at the tip of the chromosome 6. The primers were designed according to the SNP/InDel difference between parents, and the polymorphic primers were screened in both parents and extreme pools, and the molecular markers PP5 and OP59 were obtained. The accuracy of the two markers was 100% in extreme population validation; The marker OP59 was a co-dominant marker, which was located at the candidate gene T459-15819 interval of 17 232 bp. The accuracy of the marker was 100% in the sterile population and 97.21% in the fertile population; PP5 was located 318 bp downstream of the candidate gene T459-15819 of the restorer gene. The accuracy of PP5 was 100% in both sterile and homozygous fertile populations. In this study, we obtained two markers closely linked with the restorer gene, which would lay the foundation for accelerating the selection of CMS restorer lines in pepper.

A technique system for detecting the genome size of Camellia oleifera by flow cytometry was established to analyze the genome size genetic diversity between the superior lines of C. osmantha var. Yilu and C. vietnamensis var. Hongu 23, and to provide reference for selection of special germplasm and analysis of ploidy difference, based on the key links such as the type of dissociated liquid, the plant of internal reference, the tissue organ of the test material, evaluation indexes such as the nuclear dissociation, the degradation of secondary metabolites, the stability of the cell peak, the clear degree of the main peak, the separation degree of the main and miscellaneous peak, the easy degree of sampling, the difference of the genome size of the internal participating samples, the accuracy of genome size determination and the coefficient of variation. The method was used to determine the genome size of the superior lines of C. osmantha and C. vietnamensis. The disintegrating effect of WPB and mG^b was better among common dissociative fluids WPB, Tris-MgCl₂, OTTO, mG^b. Pean and corn were the favorable internal plants, and young leaf or root tip were the favorable experimental materials. The genome size of the superior lines of C. osmantha was from 5.12 to 9.31 Gb, with an average value of 7.60 Gb, the genome size distribution of the superior lines No. 1, No. 37 and No. 45 was extreme, and it was speculated that there were ploidy differences or interspecific hybridization between the parents. The genome size of superior lines of C. vietnamensis varied from 9.17 to 9.85 Gb, the mean value was 9.47 Gb. There was significant difference in genome size between the superior lines of C. osmantha and C. vietnamensis.

Paris polyphylla var. alba, a medicinal plant of Melanthiaceae, is classed as the national second-grade protected species of China. With the increasing demand for raw materials of Rhizoma paridis, the wild resources of P. polyphylla var. alba have been seriously damaged. In order to protect the genetic resources and clarify the systematic positon of this species, Illumina Hiseq X Ten platform was used to sequence the chloroplast (cp) genome. The structural characteristics of the complete cp genome sequence and phylogenetic relationship of P. polyphylla var. alba in Paris were analyzed. The results showed that the cp genome was 163 944 bp in length with a typical quadripartite structure with a large single-copy (LSC) region of 84 179 bp, a small single-copy (SSC) region of 12 967 bp, and a pair of 33 399 bp inverted repeats (IRs). The genome contained 134 genes, including 88 protein-coding genes (PCGs), 38 tRNA genes and 8 rRNA genes. A total of 645 long repeats and 97 simple sequence repeats (SSRs) loci were detected in the complete cp genome, in which forward and palindromic repeats were the mainly long repeat types, and most of SSRs had A/T base preference. Phylogenetic analysis based on the complete cp genomes showed that Paris formed a monophyletic group, and could be further divided into five major clades corresponding to five sections, respectively. The varieties of P. polyphylla are located in Sect. Euthyra, but are not clustered a monophyletic group, and P. polyphylla var. alba is closely related to P. mairei. This study would provide a scientific basis for studying the phylogeny, species identification and resource conservation of Paris.

During the evolution from lower plants to higher plants, lignification is the key to adapt to the terrestrial environment, while lignin deposition in the cell wall is an important manifestation of lignification, and MYB61 plays an important role in lignin synthesis pathway. In order to explore the molecular mechanism of MYB61 in lignin synthesis of Impatiens chlorosepala and Impatiens uliginosa, MYB61 genes, named IcMYB61 and IuMYB61 in this study, were cloned by using the RT-PCR method. The full-length cDNA was 1035 bp and 1002 bp, encoding 344 aa and 333 aa, containing an intron of 84 bp and 66 bp, respectively. Physicochemical analysis suggested that IcMYB61 and IuMYB61 were unstable hydrophilic protein. Domain analysis of protein showed that IcMYB61 and IuMYB61 contained two typical SANT conserved domains. The comparison of amino acid sequences of MYB61 with that of other species showed that there were highly conserved R2 and R3 regions at the N-terminal, which was speculated to be R2R3-MYB gene. Based on the phylogenetic analysis, it found that IcMYB61 and IuMYB61 were clustered together with I. glandulifera, confirming that the same genus is more closely related. The qPCR showed that IcMYB61 and IuMYB61 were expressed in three different parts of the two periods, and the expression levels were the lowest in roots. In I. chlorosepala, the highest expression of IcMYB61 was in the leaves at the seedling stage, and the highest expression level was in the stem at the mature stage. In I. uliginosa, the expression of IuMYB61 was the highest in the stems of both periods. By measuring the total lignin content in stems and leaves of the two species, it was found that the lignin content of both species was the highest in stems, which was consistent with the expression trend of MYB61. It is speculated that MYB61 mainly regulates the biosynthesis of lignin in the stems of I. chlorosepala and I. uliginosa. The above-mentioned results would provide some basic data and scientific basis for exploring the regulation mechanism of MYB61 on the lignin synthesis of Impatiens and the culture of new varieties.

Verticillium wilt, a soil-borne disease caused by Verticillium spp., is one of the most important diseases in eggplant production. It seriously affects the yield and quality of eggplant. At present, the control methods for eggplant verticillium wilt are limited to grafting and chemical controls, but neither of them can prevent the occurrence of verticillium wilt. The best way to control Verticillium wilt is to explore the verticillium wilt resistance genes in eggplant and to breed some resistant eggplant varieties with genetic engineering technology. Solanum symbriifolium Lam. is a wild eggplant in Yunnan, China with a high Verticillium wilt resistance. PR genes encode pathogenesis-related proteins, which are closely related to plant disease defense. Among them, PR10 protein is a nuclease-like protein, and the defense mechanism of PR10 protein in S. sisymbriifolium is still unclear. In this study, a wild eggplant S. sisymbriifolium was used as the experimental material. The pathogenesis related protein 10 (PR10) homologous gene was isolated and cloned by reverse transcription PCR (RT-PCR) technology from the previously established transcriptome database of S. sisymbriifolium and named as SsPR-10. The cloned sequence length of SsPR-10 was 645 bp, and its coding region was 480 bp long, encoding a protein of 159 amino acids residues in total. And the bioinformatics analysis showed that SsPR-10 protein was an acidic hydrophilic protein with a molecular mass of 17.71 kDa and a theoretical isoelectric point (pI) of 5.54. The prediction of transmembrane region and signal peptide showed that SsPR-10 protein had no transmembrane region and signal peptide. The prediction for subcellular localization showed that SsPR-10 was localized in the cytoplasm of plant cell. The results of conserved domain prediction showed that SsPR-10 contained a "P-LOOP" circle structure (sequence positions at 47-52 bp) and conserved sequence PATHOGENESIS_BETVI (sequence positions at 88-120 bp). The sequence alignment and phylogenetic tree analysis showed that SsPR-10 protein had the highest homology with PR10 protein from S. virginianum, followed by STH-2 protein from S. tuberosum. The expression of SsPR-10 gene was analyzed by real-time fluorescence quantitative PCR (RT-qPCR) experiments, and the expression level of SsPR-10 was the highest in the root than in other organs of S. sisymbriifolium, showing a tissue specificity. The expression level of SsPR-10 was multiplied to 8.16 times at 24 h after inoculation with V. dahliae, indicating that verticillium wilt might induce the expression of SsPR-10. In this study, SsPR-10 gene was cloned and its expression pattern was analyzed in the wild eggplant S. sisymbriifolium for the first time, which will provide a theoretical basis for further studying the mechanism of SsPR-10 responding to Verticillium wilt and other biological stresses.

In order to understand the flora characteristics of wild seed plants in Mashan county, Guangxi, the wild seed plant resources were investigated. The results showed that there were 1504 species of wild seed plants in Mashan county, Guangxi, belonging to 170 families and 740 genera. Angiosperms were dominant and gymnosperms were relatively scarce. From the perspective of family and genus composition, monospecific families and oligospecies were the main body, while the genera and species of seed plants were concentrated in medium and large families, small genera and monospecific genera. The plant distribution area was rich in types, with obvious tropical nature and certain temperate components, showing a transitional nature from tropical to subtropical. Compared with neighboring areas, Mashan county has richer plant diversity, and its flora is the closest to Binyang county, Guangxi. In general, Mashan county is rich in plant diversity, with prominent tropical components, rich in life and mainly herbaceous plants, with ancient and young flora coexisting, and the unique phenomenon is prominent, reflecting the characteristics of the flora of the Beibu Gulf as a whole.

Ardisia gigantifolia Stapf is native to Hekou county, Yunnan province, with few wild individuals, and is listed as a critically endangered species. It has important protection value and good prospect of garden development and application. The stem segments of aseptic seedlings of A. gigantifolia were used as the explants to establish a propagation in vitro. The results showed that the optimal medium for callus induction was WPM+0.50 mg/L TDZ+0.10 mg/L NAA, and the induction rate of callus was 96.67%. The optional medium for callus proliferation was WPM+0.50 mg/L TDZ and the multiplication coefficient was 4.42. The optimal medium for callus differentiation was WPM+2.00 mg/L 6-BA+0.20 mg/L NAA, and the induction rate reached 100%. The optional medium for adventitious bud proliferation culture was WPM+4.00 mg/L 6-BA, the multiplication coefficient was 3.90, and the cluster buds grew well. The optional rooting medium was WPM+10% coconut water+0.20 mg/L NAA, the rooting rate reached 100%, the root system developed well and the test-tube plantlets grew vigorously. Plantlets were transplanted into the mixture substrate with the volume ratio of perlite and peat soil of 1∶3, the survival rate was 96.67% after 60 days and plants grew well. This study can provide technical support for the large-scale seedling production of A. gigantifolia, as well as theoretical basis and technical support for the protection, seedling breeding, and molecular biology research of this species.