Transcriptional Responses Involved in the Interaction between Capsicum annuum and the PGPB Bacillus zhangzhouensis Under Salt Stress

Capsicum annuum is the most widely grown spice crop worldwide. However, salinity is one of the major abiotic stresses that affects crop plants. Our previous reports have identified Bacillus zhangzhouensis as effective in alleviating C. annuum salt stress. In this work, the RNA-seq analysis of plants under salt stress, grown with and without B. zhangzhouensis was used to elucidate plant salt-stress-alleviating mechanisms. Capsicum annuum plants were cultivated under the following conditions: (i) plants without salt stress, (ii) plants under salt stress, (iii) plants inoculated with B. zhangzhouensis without salt stress, and (iv) plants inoculated with B. zhangzhouensis and salt stress. Leaf tissue samples were collected at the end of the experiment. A total of 101 984 contigs were assembled, and the differentially expressed genes (DEGs) were obtained for each treatment. The results showed that salt stress led to a greater number of DEGs in C. annuum. Likewise, the presence of B. zhangzhouensis decreased the number of DEGs. Moreover, the analysis by GO and KEGG showed 6 main metabolic pathways involved in the three treatments. Finally, the results showed that the ethylene pathway was one of the main pathways involved in the response to the different treatments. In conclusion, our data provide a better understanding of the transcriptional changes in the molecular mechanism by which these bacterial inoculants ameliorate the deleterious effect of salt stress in C. annuum plants.