Maize mutant hybrids with improved drought tolerance and increased yield in a field experimental setting

Abstract

Previous studies determined that maize mutants in miR394-regulated genes, ZmLCR1 and ZmLCR2, are more tolerant than wild-type seedlings to prolonged periods of drought. In order to evaluate the effect of these mutations in a genetic background more similar to that of maize commercialization, in this work we evaluate growth of double mutant hybrid plants in W22/B73 genetic background and also evaluated plant fitness, flowering and yield in experimental plots under two watering regimes, and compared the nutritional content of wild-type and mutant hybrids. Our results show that mutant hybrid seedlings exhibit improved physiology under normal watering conditions as well as in drought conditions, exhibiting an increase in epicuticular wax content, unaltered membrane damage in drought and lower ROS production, supporting higher survival after severe drought for double mutant hybrid seedlings. We also established that the hybrid mutants grown in typical agricultural conditions do not show differences in flowering time or in physiological and nutritional aspects, but they present a higher yield in comparison to wild-type W22/B73 hybrids, as determined by higher ear weight and number of kernels per ear in mutant hybrids, when grown in field rainfed conditions. HighlightsO_LIDouble mutants in miR394-regulated genes, ZmLCR1 and ZmLCR2, show enhanced drought tolerance in hybrid maize seedlings, with improved physiological traits under both normal and stress conditions. C_LIO_LIMutant hybrids exhibit increased epicuticular wax accumulation and reduced ROS production, supporting greater survival during prolonged drought stress. C_LIO_LIField-grown mutant hybrids in a W22/B73 background maintain normal flowering time and nutritional composition, indicating no agronomic penalties from the mutations. C_LIO_LIYield is significantly higher in mutant hybrids compared to wild-type controls, as shown by increased ear weight and kernel number under rainfed field conditions. C_LIO_LIThese findings highlight ZmLCR1 and ZmLCR2 as valuable targets for breeding drought-tolerant, high-yielding maize cultivars suited to production environments. C_LI