Modulation of energy homeostasis in maize and Arabidopsis to develop lines tolerant to drought, genotoxic and oxidative stresses

Abiotic stresses cause crop losses worldwide that reduce the average yield by more than 50%. Due to the high energy consumed to enhance the respiration rates, the excessive reactive oxygen species release provokes cell death and, ultimately, whole plant decay. A metabolic engineering approach in maize ( Zea mays ) altered the expression of two poly(ADP-ribosyl)ation metabolic pathway proteins, poly(ADP-ribose) polymerase ( PARP ) and ADP-ribose-specific Nudix hydrolase ( NUDX ) genes that play a role in the maintenance of the energy homeostasis during stresses. By means of RNAi hairpin silencing and CRISPR/Cas9 gene editing strategies, the PARP expression in maize was downregulated or knocked down. The Arabidopsis NUDX7 gene and its two maize homologs, ZmNUDX2 and ZmNUDX8 , were overexpressed in maize and Arabidopsis . Novel phenotypes were observed, such as significant tolerance to oxidative stress and improved yield in Arabidopsis and a trend of tolerance to mild drought stress in maize and in Arabidopsis . Key words: poly(ADP-ribose) polymerase, Nudix hydrolase, CRISPR/Cas9, maize, oxidative stress, drought stress