Maize mutants in miR394 ‐regulated genes show improved drought tolerance

Abstract

Water limitation represents one of the major threats to agricultural production, whichoften leads to drought stress and results in compromised growth, development andyield of crop species. Drought tolerance has been intensively studied in search ofpotential targets for molecular approaches to crop improvement. However, droughtadaptive traits are complex, and our understanding of the physiological and geneticbasis of drought tolerance is still incomplete. The miR394-LCR pathway is a conserved regulatory module shown to participate in several aspects of plant growth anddevelopment, including stress response. Here, we characterized the miR394 pathwayin maize, which harbours two genetic loci producing an evolutionarily conservedmature zma-miR394 targeting two transcripts coding for F-Box proteins, namedhereby ZmLCR1 and ZmLCR2. Arabidopsis plants overexpressing the zma-MIR394Bgene showed high tolerance to drought conditions compared to control plants. Moreover, analysis of the growth and development of single and double maize mutantplants in ZmLCR genes indicate that these mutations do not affect plant fitness whenthey grow in normal watering conditions, but mutants showed better survival thanwild-type plants under water deprivation conditions. This increased drought tolerance is based on more efficient intrinsic water use, changes in root architecture andincreased epicuticular wax content under water-limiting conditions. Our results indicate that the miR394-regulated ZmLCR genes are involved in drought stress tolerance and are remarkable candidates for maize crop improvement.