Identification of miRNAs and their targets in Phaseolus vulgaris L. under drought stress and PGPRs

To study the effect of miRNA and PGPR on drought tolerance, Sadri and Yas bean genotypes were subjected to drought conditions (FC = 90%, 60% and 30%) and bacterial treatments (no bacteria, isolates B1, B2 and mixture 2 bacterial isolates), using CRD design with three replications in a factorial arrangement, Drought stress was applied five weeks after planting (for 10 days) and second trifoliate and root were used for sampling. The results showed that PGPRs lead to membrane stability, root development, etc. To identify the potential miRNAs involved in drought stress, the publicly available EST sequences of the plant were obtained from NCBI and blasted against the previously known Plant miRNAs. Ultimately, five distinguished potential miRNAs were acquired in the plant (belonging to four families: miR408, miR5021, miR5565e and miR9559). Candidate miRNAs were involved in growth, stress tolerance, etc. miR9559-3P expression decreased in drought and bacterial inoculation conditions in drought sensitive and tolerant plants. However, in the absence of bacterial inoculation, the expression of miR9559-3P was higher in sensitive plants. miR9559-3P might increase sensitivity to drought stress by negatively regulating role and targeting a higher percentage of target genes in sensitive plants. However, the tolerant plant with a special regulatory display and reduced expression of miR9559-3P reduced the degradation of miR9559-3P transcripts, increased the expression of the target gene and improved stress tolerance. Since PGPR modulate miRNA expression and lead to drought tolerance and increase plant yield, using these bacteria as biofertilizer can be a suitable alternative method of chemical fertilizer.