RT Journal Article SR Electronic T1 The rice bundle sheath produces reactive oxygen species during high light stress via NADPH oxidase JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.07.06.189381 DO 10.1101/2020.07.06.189381 A1 Haiyan Xiong A1 Lei Hua A1 Ivan Reyna-Llorens A1 Yi Shi A1 Kun-Ming Chen A1 Nicholas Smirnoff A1 Johannes Kromdijk A1 Julian M. Hibberd YR 2020 UL http://biorxiv.org/content/early/2020/07/09/2020.07.06.189381.abstract AB When exposed to high light plants produce reactive oxygen species (ROS). In Arabidopsis thaliana local accumulation of ROS preferentially takes place in bundle sheath strands, but little is known about how this response takes place. Using rice and the ROS probes diaminobenzidine and 2’,7’-dichlorodihydrofluorescein diacetate, we found that after exposure to high light, ROS were produced more rapidly in bundle sheath strands than mesophyll cells. This response was not affected either by CO2 supply or photorespiration. Consistent with these findings, deep sequencing of mRNA isolated from mesophyll or bundle sheath strands indicated balanced accumulation of transcripts encoding all major components of the photosynthetic apparatus. However, transcripts encoding several isoforms of the superoxide/H2O2-producing enzyme NADPH oxidase were more abundant in bundle sheath strands than mesophyll cells. ROS production in bundle sheath strands was reduced by blocking NADPH oxidase activity pharmacologically, but increased when the bundle sheath preferential RBOHA isoform of NADPH oxidase was over-expressed. NADPH oxidase mediated accumulation of ROS in the rice bundle sheath was detected in etiolated leaves lacking chlorophyll indicating that high light and NADPH oxidase-dependent ROS production is not dependent on photosynthesis.Competing Interest StatementThe authors have declared no competing interest.