AUTHOR=Lu Shuai , Chen Yaoyu , Wang Surong , Han Binying , Zhao Chenglei , Xue Penghui , Zhang Yue , Fang Hui , Wang Baohua , Cao Yunying 

TITLE=Combined metabolomic and transcriptomic analysis reveals key components of OsCIPK17 overexpression improves drought tolerance in rice

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 13 - 2022

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1043757

DOI=10.3389/fpls.2022.1043757

ISSN=1664-462X

ABSTRACT=The calcineurin B-like (CBL) protein interacts with CBL-interacting protein kinase (CIPK), which is involved in responses to an array of environmental stresses; however, the response of rice OsCIPK17 to drought remains unknow. Previously, we found that OsCIPK17-overexpressing plants showed increased root biomass and enhanced drought tolerance compared with the parental Nipponbare (NIP, Oryza sativa L. ssp. Japonica). Here, to clarify the molecular mechanism of OsCIPK17 in drought response, untargeted metabolomic and transcriptomic analyses were performed on the roots of NIP and OsCIPK17-overexpressing plants under simulated drought stress. OsCIPK17-overexpressing plants showed significantly increased levels of reducing sugars, such as erythrulose, mannose, and α-D glucose, rather than sucrose, to maintain their osmotic potential, indicating that these plants adopted a unique metabolic strategy to cope with drought. Further, levels of the differential metabolite trehalose-6-phosphate (T6P) were significantly decreased but the expression of gene encoding trehalase was increased in OsCIPK17-overexpressing plants. Therefore, OsCIPK17 is involved in T6P synthesis, and the energy required for drought tolerance may be directly dependent on trehalose metabolism. Overall, in OsCIPK17-overexpressing plants, drought stress decreased the contents of metabolites other than citric acid involved in the tricarboxylic acid (TCA) cycle, suggesting that energy is stored in the form of citric acid under drought stress to facilitate rapid activation of the TCA cycle and mitochondrial function before glycolysis after drought ends. Under exogenous citric acid treatment, the plant height and root length of overexpression line was significantly increased and the genes related to auxin were significantly up-regulated. And exogenous citric acid treatment increased the drought tolerance of overexpressed rice. Next, the UDP-glucosyltransferase 79-like protein (OsUGT79) was screened using differential gene and metabolite association analyses. Yeast two-hybrid assay and bimolecular fluorescence complementation experiment revealed that OsUGT79 interacts with OsCIPK17 to regulate the growth and development of rice roots under drought stress. Analysis of UDP-glucosyltransferase family members, OSUGT79 may be involved in the synthesis of IAA. Therefore, citric acid as a means of energy regulation and OsUGT79 as a target gene of OsCIPK17 may be used to mention drought resistance through the auxin pathway.