AUTHOR=Yan Huimin , Sun Hongzheng , Jia Xueying , Lv Chuanwei , Li Junzhou , Zhao Quanzhi 

TITLE=Phenotypic, Transcriptomic, and Metabolomic Signatures of Root-Specifically Overexpressed OsCKX2 in Rice

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.575304

DOI=10.3389/fpls.2020.575304

ISSN=1664-462X

ABSTRACT=<p>Cytokinins are crucial signaling molecules that regulate plant growth and development. <italic>OsCKX2</italic> irreversibly degrades nucleobase cytokinins by encoding cytokinin oxidase/dehydrogenase to control grain production in rice. In this study, <italic>OsCKX2</italic> was specifically overexpressed in roots using <italic>RCc3</italic> promoter to investigate the effects of root-source cytokinins on the growth of rice. <italic>OsCKX2</italic> overexpressed (OE) rice showed retarded growth with lower cytokinin levels and biomass production. Shoot-specific transcriptome analysis between <italic>OsCKX2</italic> OE rice and wild type (WT) revealed differentially expressed genes (DEGs) associated with cell division, cell wall structure, phytohormone signaling, and assimilation and catabolism. Metabolome analysis indicated that a majority of differential primary metabolites, such as amino acids and organic acids, increased, while lipids decreased in <italic>OsCKX2</italic> OE rice. Integration of transcriptomic and metabolomic data showed that several DEGs and differential metabolites were related to glycolysis and tricarboxylic acid cycle (TCA). To conclude, reduced cytokinin levels via root-specific overexpression of <italic>OsCKX2</italic> resulted in developmental defects, which confirmed the importance of root-source cytokinins in plant growth and morphogenesis.</p>