Overexpression of ZmEULD1b enhances maize seminal root elongation and drought tolerance.

Drought stress damages the growth and development of maize, which results in the maize yield reduction. A strong root system improves the drought tolerance in maize. A previous genome-wide association study for the maize seminal root length under drought stress conditions identified a significant SNP, which was located in the ZmEULD1b gene. Here, we show that enhancing ZmEULD1b expression in transgenic maize increases seminal root length, as well as plant tolerance to water deficit. Meanwhile, ZmEULD1b overexpression influences the stomatal development and promotes water-use efficiency of maize. Further, transcriptome analysis of wild type and ZmEULD1b-OE plants show that several peroxidases and ABA-related pathway genes are upregulated in the ZmEULD1b-OE plants under drought stress conditions. Additionally, rhizosphere microbiota analyses of plant root confirm that overexpression of ZmEULD1b improves the abundance of growth-promoting microbes in the maize root system under drought stress conditions. Collectively, the data presented in this work suggest that ZmEULD1b could be a valuable gene resource or selection target for the drought-tolerant genetic improvement of maize.