RCA Regulates Stem Cell Homeostasis And WUS Expression In Shoot Apical Meristem Of Arabidopsis

Plant growth depend on the continuous maintenance and differentiation of stem cells.WUS is expressed at the organizing center at the shoot apical meristem(SAM)and is very important for maintenance of stem cell homeostasis.Plant growth is also affected by external environmental conditions.Among them,light is an important environmental signal that activates the expression of WUS gene and regulates stem cells function at SAM.However,it is not known how light regulates WUS expression.Rubisco is the core enzyme photosynthesis,RCA plays an important role in the activation of Rubisco.Existing studies mainly include the mechanism of RCA activating Rubisco,the W of RCA protein,the response of RCA protein to light,the response of RCA to redox,and the response of RCA to energy.However,it is unclear whether RCA,which can sense light and energy signals during photosynthesis,can also regulate other developmental processes of plants.Our results showed that RCA can interact with WUS to form a complex,which can bind to the WUS promoter to activate WUS expression.Overexpression of RCA can activate WUS expression in the dark,while overexpression of RCA-SRDX protein can inhibit WUS expression under light conditions.The expression of RCA-SRDX under the control of the promoter of SUC2 gene,which is specifically expressed in leaf vascular bundles,can also inhibit WUS expression,suggesting that RCA can be transported from leaf to the SAM over a long distance to regulate SAM.In summary,chloroplast protein RCA can interact with WUS and positively regulate the expression of WUS gene at the transcription level in response to light signaling.