Analysis of endophytic bacterial diversity in seeds of different genotypes of cotton and the suppression of Verticillium wilt pathogen infection by a synthetic microbial community.

BACKGROUND: In agricultural production, fungal diseases significantly impact the yield and quality of cotton (Gossypium spp.) with Verticillium wilt posing a particularly severe threat. RESULTS: This study is focused on investigating the effectiveness of endophytic microbial communities present in the seeds of disease-resistant cotton genotypes in the control of cotton Verticillium wilt. The technique of 16S ribosomal RNA (16S rRNA) amplicon sequencing identified a significant enrichment of the Bacillus genus in the resistant genotype Xinluzao 78, which differed from the endophytic bacterial community structure in the susceptible genotype Xinluzao 63. Specific enriched strains were isolated and screened from the seeds of Xinluzao 78 to further explore the biological functions of seed endophytes. A synthetic microbial community (SynCom) was constructed using the broken-rod model, and seeds of the susceptible genotype Xinluzao 63 in this community that had been soaked with the SynCom were found to significantly control the occurrence of Verticillium wilt and regulate the growth of cotton plants. Antibiotic screening techniques were used to preliminarily identify the colonization of strains in the community. These techniques revealed that the strains can colonize plant tissues and occupy ecological niches in cotton tissues through a priority effect, which prevents infection by pathogens. CONCLUSION: This study highlights the key role of seed endophytes in driving plant disease defense and provides a theoretical basis for the future application of SynComs in agriculture.

[Genome-wide identification, phylogenetic analysis and expression profiling of the MKK gene family in Arabidopsis pumila].

Mitogen-activated protein kinase kinase (MAPKK or MKK) is an important component of the MAPK cascade, which plays important roles in plant growth and development as well as in various stress responses. At present, the MKK gene family has been identified in a variety of plants, but there has been no systematic study in Cruciferous plant Arabidopsis pumila. To explore the evolution and function of the MKK gene family in Arabidopsis pumila, 16 ApMKK genes were identified from the Arabidopsis pumila genome by genome-wide analysis, and they were distributed on 10 chromosomes of Arabidopsis pumila. According to phylogenetic analysis and multiple sequence alignment, these putative genes were divided into five known subfamilies, i.e, Groups A, B, C, D, and E, which includes 5, 2, 4, 3, 2 members, respectively. Evolutionary and syntenic analysis showed that there are seven pairs of duplication genes in Arabidopsis pumila: ApMKK1-1/1-2, ApMKK2-1/2-2, ApMKK3-1/3-2, ApMKK4-1/4-2, ApMKK5-1/5-2, ApMKK9-1/9-2, and ApMKK10-1/10-2. Ka/Ks and Tajima analysis indicated that evolution of ApMKK1-1/1-2 was accelerated after the duplication event. Combining the distribution of cis-element in the promoter region of ApMKKs and the expression profile of ApMKKs in mature leaves, stems, flowers and fruits as well as under salt stress, we found that the expressions of paralogous genes (duplication genes) were tissue-specific and their functions were diversified. The expression patterns of some duplicated genes in tissues were different, but the expression patterns under salt stress were basically the same. These results lay the foundation for analyzing the complex mechanisms of MKK-mediated growth and development and abiotic stress signal transduction pathways in Arabidopsis pumila.