In this study, seven LysM-RLK subfamily genes were systematically identified in the whole genome of papaya using bioinformatics methods, and the chromosome distribution, gene structure, protein physical and chemical properties, and subcellular localization information were analyzed. Familial evolutionary analysis showed that papaya LysM-RLK could be further divided into three subgroups (Lym-Ⅱ, Lym-Ⅲ, Lym-Ⅳ), distributed on four chromosomes. Recent gene replication is the main driver of the evolution of the papaya LysM-RLK subfamily. The analysis of promoter sequence regulatory elements found that it contained multiple photoresponse elements and elements involved in low temperature response and stress related hormone signal response. Large-scale comparative transcriptome analysis systematically analyzed the gene expression patterns of LysM-RLK under papaya biostress and abiotic stress and different tissues, revealing its specific expression patterns and potential biological functions. The expression differentiation of replicating gene pairs, differences in domain composition, and changes in the tertiary structure of proteins suggest subfunctionalization in the process of evolution. Core co-expression network analysis under biotic and abiotic stress conditions identified 27 core genes strongly associated with LysM-RLK3, revealing the potential transcriptional regulatory patterns of LysM-RLK3. The results would provide important insights into the evolution, functional differentiation and role of the papaya LysM-RLK subfamily in adversity response and growth and development.

In order to reveal the genome characteristics of HNU24, which has excellent antagonistic ability to Ralstonia solanacearum, its complete genome was sequenced by the BGISEQ-500 and ONT PromethION technology, and the genome assembly, gene prediction, function annotation, and protein homology analysis also were conducted. Phylogenetic analysis results demonstrated that HNU24 belonged to Bacillus velezensis. Its completed genomic sequence length was 3 932 768 bp, GC content was 46.48%, and had 3822 genes. A total of 43 carbohydrate active enzyme gene families were identified in the genome, and the cellulase activity experiment further confirmed that the strain HNU24 had the ability to degrade cellulose. Thirteen clusters of secondary metabolite biosynthesis genes were predicted in genome, including eight compounds: surfactin, fengycin, plantazolicin, butirosin A/butirosin B, macrolactin, bacillaene, difficidin, bacillibactin and bacilysin, which have been reported as the antibacterial components. Five unknown components, which were found no homologous genes or were less similar to the known database sequences, may be new compounds that have not been identified and reported. In addition, greenhouse experiment demonstrated that HNU24 had significant growth promoting effect on tomato plants. Thus, HNU24 may antagonize R. solanacearum and promote tomato growth by secreting active compounds, and it is a potential biofertilizer strain. The relevant results would lay a foundation for further research and application of HNU24 in biological control.

Cyperus esculentus is a special oil crop, with its underground tuber accumulating a large amount of oil, and also having the advantages of wide adaptability and strong stress resistance. This crop is a superior germplasm material for studying plant stress resistance and oil enrichment in the underground vegetative organs. Transport inhibitor response protein 1 (TIR1) can regulate plant growth and development and abiotic stress response as an auxin receptor. However, few reports on CeTIR1 have been reported. In this study, four TIR1 genes, namely CeTIR1-1, CeTIR1-2, CeTIR1-3 and CeTIR1-4, were identified from C. esculentus transcriptome data and the ORFs were further cloned by RT-PCR. All the four CeTIR1 proteins contained a typical F-box protein domain, AMN1 superdomain and Transp_inhibit domain, revealed by bioinformatics analysis. No significant difference was detected among the four CeTIR1 proteins in regarding sequence length, relative molecular weight, isoelectric point and other physicochemical properties. The four CeTIR1s were closely related to TIR1s derived from plants of Cyperaceae, Oleaceae and Cruciferae in the evolution. Gene expression profiling showed that the expression levels of CeTIR1 family genes were significantly different in different tissues of C. esculentus, with the highest expression in tuber tissues and lower expression in root and leaf tissues. The antioxidant enzyme activity and MDA content of C. esculentus seedlings increased under salt stress. After adding exogenous IBA treatment, the antioxidant enzyme activity of C. esculentus seedlings under salt stress further increased whereas the MDA content decreased. This indicated that IBA could alleviate the adverse effects of salt stress on the growth of C. esculentus seedlings. qRT-PCR results showed that expression levels of the four CeTIR1 genes increased in C. esculentus seedlings treated with salt stress, and exogenous addition of IBA could significantly up-regulate the expression of CeTIR1-2 gene. Comprehensive analysis demonstrates that CeTIR1-2 may be an important gene involved in regulating the response of C. esculentus seedlings to salt stress. Together, the results would provide the scientific basis and important reference for exploring the related function genes involved in auxin regulating the growth and development and stress resistance of C. esculentus, as well as the C. esculentus cultivation in the saline-alkali land.

In three Camellia vietnamensis producing areas of southwest tropical rainforest in Hainan Province, Baomeiling Ecological Protection Reserve (JB), Bawangling Gibbon Reserve (QS), and Jiangpai Village (XS), Baisha Li Autonomous County, 22 high-yielding single strains were selected, for primary screening and comparison. Observe fruit yield per unit area, oil content rate of fresh fruit, grude oil yield per unit of crown area, peroxide value, iodine value, acid value, saponification value and the contents of palmitic acid, stearic acid, oleic acid, linoleic acid, myristic acid, palmitoleic acid, linolenic acid, arachidic acid, eiconsenoic acid in seed oil for 3 years, after the data was treated with the methods of ANOVA, gray association analysis, and cluster analysis, then screen out the more superior single strains. There existed significant difference in grude oil yield per unit of crown area, oil content rate of fresh fruit and fruit yield per unit area, among them, fruit yield per unit area might be the key indicator of high-yield screening. The physicochemical nature and fatty acid content of camellia seed oil both meet the requirements of "oil-tea camellia seed oil" (GB/T 11765—2018), but there existed some significant difference in some indicators, and there existed the linear correlations between some saturated and unsaturated fatty acids, then there existed the phenomena of the saturated acids changed into unsaturated acids, indicating that the camellia seed oil has no quality problems, and the different tree had its specific characteristic, so the breeding target should be mainly high yield and stable yield, and iodine value, saponification value and the contents of oleic acid might be the effective indicators for selection. Known from the grey association analysis data, the single strains with superior integrated traits were successively JB2, JB7, QS6, JB1, QS5, XS2, JB4, XS4, JB9 and XS5 respectively; Known from the clustering results, it is better to gather all the individual strains into 9 categories (r=0.904), among them, the top seven single strains of comprehensive traits were clustered in Ⅰ, Ⅸ,Ⅶ and Ⅵ respectively, indicating it was expected to screen out the characteristic diverse varieties. JB2, JB7, QS5, XS2 and XS4 belonged to the expected individual strains whose comprehensive behaviors in economic traits were excellent, and JB2 among them was the best one and rare.

In order to explore the pollution level and source of soil heavy metals in Haikou City, taking the agricultural land in Haikou City as the research object, the content of eight kinds of heavy metals such as Cd, Hg, As, Pb, Cr, Cu, Ni and Zn in soil surface samples were collected and determined, and the spatial distribution characteristics of heavy metals were clarified combined with geostatistical analysis method. The single factor pollution index method, geo-accumulation index method and potential ecological risk index method were used to evaluate soil pollution. The source of heavy metals was quantitatively analyzed by the correlation analysis and principal component analysis/absolute principal component fraction (PCA/APCS) receptor model. Six heavy metals such as Cd, Pb, Cr, Cu, Ni and Zn exceeded the risk screening value of agricultural land, and the proportion of exceeding the standard points from high to low was Cr, Ni (31.6%)>Cu (21.1%)>Cd (5.3%)>Pb and Zn (2.6%). The spatial distribution characteristics of Cu, Zn, Ni and Cr contents were basically the same, which were similar to the distribution of basic volcanic rocks in the study area. The evaluation results of heavy metal geo-accumulation index showed that the concentration of Cd in the soil was the highest, and the soil was greatly affected by Cd, followed by Cr, and other heavy metals were less affected. The potential ecological risk levels of soil heavy metal pollution were mainly mild and moderate risk levels, while As, Pb, Cr and Zn were slight ecological risks, and the potential ecological harm was small. The above points of Cd, Hg and Ni intensity ecological risk accounted for 52.6%, 15.8% and 5.3% respectively. The potential ecological risk of soil heavy metals in the study area was mainly caused by Cd and Hg. Eight kinds of heavy metal elements were identified as three sources. Cu, Ni, Cr and Zn were mainly from natural sources, which were mainly affected by the high soil background value of basic volcanic parent rock, Pb, Cd, As and Hg were mainly from industrial sources and traffic sources. As was also affected by agricultural sources. The source of heavy metals in Haikou soil was relatively single. As a result, it is necessary to strengthen the pollution control of Cd, Cr and Hg in the soil, with the focus on the pollution control of Cd.

To confirm the characteristics and difference of the chloroplast (cp) genome of Colocasia esculenta var. Redbud and Colocasia esculenta var. Lipu, the two taros were taken as experimental materials in the study, their genomic DNA were first extracted form fresh leaves using an improved CTAB method and the two complete cp genomes were obtained using high-throughput sequencing technology and bioinformatics analysis, simple sequence repeat (SSR) identification, multiple sequence alignment, sliding window analysis on DNA polymorphism and phylogenetic tree analysis were then conducted on two complete cp genomes. The results showed that the length of the complete cp genomes of Redbud and Lipu was 162 478 bp and 162 453 bp, respectively, exhibiting the typical cyclic quadripartite structure. A total of 131 genes were annotated both in the two, including 86 protein-coding genes, 37 tRNA genes and 8 rRNA genes, of which 18 genes had two copies and 23 genes had introns. A total of 130 and 124 SSR sites were identified in Redbud and Lipu respectively, the content of A/T in the SSR repeats was 63.08% and 61.29% respectively. 15 SSR polymorphic primers were identified. A total of 236 cp single nucleotide polymorphism (SNP) sites were detected between Redbud and Lipu, of which 26.7% were in the gene coding region, which leading to 25 missense variant genes, the variation of the genes may promote the difference between the two varieties. Compared with the representative species from 13 genus of Aroideae showed that the structure, types, and numbers of gene were relatively conservative. The trnS-trnG and ndhF-rpl32 were the highest variation sites in SSC and LSC region, respectively. The phylogenetics analysis using maximum likelihood method (ML) showed that the genus Colocasia had the closest relationship with the genus Steudnera, but the farthest relationship with the genus Sauromatum in the Ariodeae. The results would provide a theoretical basis for the germplasm resource exploitation, genetic diversity evaluation and phylogenetic analysis of C. esculenta.

Species diversity is the most basic level of biodiversity, which not only reflects the richness of biological species, but also the spatial scope of species evolution and the ecological adaptability to specific environments. Structure is the basis for studying the historical dynamics of plants, and while understanding and clarifying the growth competition relationship between species, it reflects the trend of community succession. Based on the results of 62 plots with a total area of 3.72 hm², the species diversity and structure of tree populations of Dagangshan were analyzed. There were 486 species of plants in the community, belonging to 286 genera of 120 families, of which single species accounted for 66.43% of the total, and China fir were in a dominant position in the community. Dagangshan is located in the subtropical region and has the nature of transition zone. The genus of seed plants included 13 distribution types, and 9 genera with endemic components in China. Shannon-Weiner index, Simpson index and Pielou index were basically the same in the distribution trend of each growth layer. The advantage of shrub layer was obvious. The herbaceous layer was slightly higher than the arbor layer. The overall species diversity index of the community was higher and the species were more abundant. By sample belt, the 2nd sample was the most abundant, and the 1st sample was slightly lower than the others. However, the community similarity was the highest in the 1st and 2nd belts, and the difference in species diversity indices in the 3rd and 4th samples was small, but the community differences were the largest.

The southern ecological type of Chinese yam variety Guihuai5 was used to investigate the mutagenic effect of ⁶⁰Co-γ radiation. In a certain dose range, ⁶⁰Co-γ radiation had highly significant inhibitory effect on the germination and seedling growth of Chinese yam bulbils. The linear regression equation between the radiation dose and germination rate was y =-0.8776x+103.37. According to this, the half-lethal-dose and 40%-lethal-dose was 60.8 Gy and 72.2 Gy respectively. 40 Gy radiation treatment had no inhibitory effect on the germination, growth and development of the M₁ generation population of the bulbils. On the contrary, it showed a promoting effect in some extent. Radiation treatment induced increased tuber length, diameter and weight in the off spring plants of M₁ generation. The radiation treatment induced fascicular branching in some individual tubers in the M₁ generation, which resulted in the tuber change from long-column-shaped shape to irregular-block-shaped shape, and the weight of single tuber increased greatly. This occurred particularly in 90% of the plants harvested in the 100 Gy treatment. ⁶⁰Co- γ treatment induced mutations with twin tubers in the M₁ generation of the treated bulbils. The occurrence probability of the twin mutation was the highest in the 60 Gy treatment, accounting for 8% of the plants harvested. From the M₁ generation, 18 mutants with twin tubers, 11 mutants with large tubers and 1 mutant with female flowers were obtained. The results of this experiment indicate a bright prospect for radiation induction breeding of Chinese yam, and would provide basic materials for the further breeding of new Chinese yam varieties and lines.

Morinda officinalis How is a plant of the Rubiaceae, whose dried roots are used as medicine It can strengthen bones and muscles, nourish kidney-yang and remove wind and moisture. It is mainly distributed in Guangdong, Guangxi, Fujian and Hainan provinces. It is one of the four major southern medicines in China. In the main production areas of China, it is mainly propagated by cuttings. In the process of variety breeding, it is often disturbed by plant viruses. The viruses are transmitted and accumulated in plants through asexual propagation of plants, resulting in the inhibition of plant growth and the decline of yield and quality. Therefore, for the purpose of tissue culture detoxification of M. officinalis, the tissue culture detoxification research of M. officinalis was carried out. Thereby improving the yield and quality of M. officinalis, which is beneficial to the protection of M. officinalis species. It is of great practical significance to provide technical support for quality resources and the factory-based seedlings of M. officinalis. Using the stem segments as the explants, an efficient and stable M. officinalis tissue rapid propagation system was established, and suitable plant regeneration methods were screened out. Using 1/2MS as the basic medium, M. officinalis stem axillary buds were used to induce clustered buds to obtain the virus-free seedlings and successfully domesticated and transplanted, the virus detection of M. officinalis tissue culture seedlings and transplanted seedlings were carried out by PCR technology. The semi-lignified stem segments as the explants were suitable to induce axillary buds, the most suitable medium was 1/2MS+6-BA 0.2 mg/L, and the axillary bud induction rate was 70%. Taking the axillary buds to induce fascicled bud, the most suitable medium was 1/2MS+6-BA 0.2 mg/L, and the fascicled bud induction rate was 86.36%. The suitable medium for rooting was 1/2MS+IBA 0.5 mg/L, with a root rate of 100%. The tissue culture seedlings were transplanted in the 1∶1 peat soil-perlite matrix for 8 days with the highest survival rate, reaching 93.3%. The reverse transcript PCR was used to determine the Cucumber mosaic virus isolate M. officinalis How (CMVMO) in the tissue cultured seedlings and transplanted seedlings, the plantlets of M. officinalis How detoxified was obtained. In this study, virus-free seedlings of M. officinalis were successfully cultivated through direct organogenesis, and an in vitro rapid propagation and regeneration system of M. officinalis was established, which would not only improve the yield and quality of M. officinalis, but also provide a reference for virus-free rapid propagation and commercial production and seedling raising of M. officinalis.

To effectively monitor the occurrence and damage of dangerous pests in Zhaoshu Island, a systematic survey and risk assessment on all the pests of 90 plants in Zhaoshu Island was conducted. The results showed that there were 19 insects and mintes of 8 wild halophytes including 5 alien invasive pests and 7 world dangerous pests occurred and harmed seriously; 24 insects and mintes of 29 landscape plants including 9 alien invasive pests and 6 world dangerous pests occurred and harmed seriously; 36 insects and mintes of 31 salt-tolerant fruits and vegetables including 7 alien invasive pests and 6 world dangerous pests occurred and harmed seriously; 16 insects and mintes of 22 sand-bander plants including 5 alien invasive pests and 2 world dangerous pests occurred and harmed seriously. The results of risk assessment showed that Brontispa longissima, Paracoccus marginatus, Phenacoccus solenopsis and Opisina arenosella were all high-risk pests in Zhaoshu Island with R value 2.12, 2.12, 2.09 and 2.02, while Dysmicoccu neobrevipes, Diaspis boisduvalii, Tetranychus urticae, Thrips palmi, Bemisia tabaci, Liriomyza sativae and Bactrocera cucuribita were all moderate risk pests in Zhaoshu Island with R value 1.92, 1.89, 1.82, 1.79, 1.79, 1.74 and 1.61, respectively. The results were the first report on the occurrence and damage of plant pests in Zhaoshu Islan, which would provide an important basic information support for the effective protection of the biosafety in Zhaoshu Island.