Overexpression of miR166 in Response to Root Rhizobacteria Enhances Drought Adaptive Efficacy by Targeting HD-ZIP III Family Genes in Chickpea

Using the transgenic approach, the current study investigated the tripartite interaction of miRNA166, Plant Growth Promoting Rhizobacteria (PGPR), and chickpea crops in response to drought. miR166, an evolutionarily conserved small RNA, was cloned and transformed in a homologous manner. This Car-miR166 is reported in our previous research to have drought-enduring roles in response to microbial candidates. A Pseudomonas putida strain RA (MTCC5279) is used as a PGPR for the whole study. The overexpressed lines generated using tissue-culture practice were functionally validated with physiological parameters studied using Li-Cor 6400XT, including photosynthesis rate, transpiration rate, water-use efficiency, and electron transport rate. We also studied the relative water content of the overexpressed lines in comparison to treated control plants. In biochemical methods, we studied the accumulation of proline, superoxide dismutase, peroxidase, catalase, H₂O₂ and lipid peroxidation levels. miR166 has its target as ATHB15 (Homeobox-leucine zipper protein-15) validated using 5’ RNA Ligase-Mediated Rapid Amplification of cDNA Ends (RLM-RACE) experiment. At the molecular levels, we carried out the stem-loop quantitative real-time (qRT) PCR analysis of miR166 and the expression analysis of ATHB15 in transgenic lines. As per our study, the results reported that the transgenic lines showed a positive interaction of miR166 with PGPR, resulting in drought stress mitigation and better plant survival in harsh drought conditions. In conclusion, the physiology, biochemistry, and molecular expression levels of Car-miR166 (Cicer arietinum L.) in transgenic lines in response to PGPR support enhanced growth and development in response to PGPR in transgenic lines under drought.