OR^His, a Natural Variant of OR, Specifically Interacts with Plastid Division Factor ARC3 to Regulate Chromoplast Number and Carotenoid Accumulation  

作　　者：Tianhu Sun Hui Yuan Cheng Chen Deena K.Kadirjan-Kalbach Michael Mazourek Katherine W.Osteryoung Li Li 

机构地区：[1]Robert W.Holley Center for Agriculture and Health,USDA-ARS,Cornell University,Ithaca,NY 14853,USA [2]Plant Breeding and Genetics Section,School of Integrative Plant Science,Cornell University,Ithaca,NY 14853,USA [3]Department of Plant Biology,Michigan State University,East Lansing,MI 48824,USA

出　　处：《Molecular Plant》2020年第6期864-878,共15页分子植物（英文版）

基　　金：This work was supported by Agriculture and Food Research Initiative competitive awards grant nos.2016-67013-24612 and 2019-67013-29162 from the United States Department of Agriculture National Institute of Food and Agriculture.C.C;was supported by the United States Department of Energy,Office of Science,Basic Energy Sciences award number DE-FG02-06ER15808 to K.W.O.

摘　　要：Chromoplasts are colored plastids that synthesize and store massive amounts of carotenoids.Chromoplast number and size define the sink strength for carotenoid accumulation in plants.However,nothing is known about the mechanisms controlling chromoplast number.Previously,a natural allele of Orange(OR),OR^His,was found to promote carotenoid accumulation by activating chromoplast differentiation and increasing carotenoid biosynthesis,but cells in orange tissues in melon fruit and cauliflower OR mutant have only one or two enlarged chromoplasts.In this study,we investigated an OR^His variant of Arabidopsis OR,genetically mimicking the melon OR^His allele,and found that it also constrains chromoplast number in Arabidopsis calli.Both in vitro and in vivo experiments demonstrate that OR^His specifically interacts with the Membrane Occupation and Recognition Nexus domain of ACCUMULATION AND REPLICATION OF CHLOROPLASTS 3(ARC3),a crucial regulator of chloroplast division.We further showed that OR^His interferes with the interaction between ARC3 and PARALOG OF ARC6(PARC6),another key regulator of chloroplast division,suggesting a role of OR^His in competing with PARC6 for binding to ARC3 to restrict chromoplast number.Overexpression or knockout of ARC3 in Arabidopsis OR^His plants significantly alters total carotenoid levels.Moreover,overexpression of the plastid division factor PLASTID DIVISION 1 greatly enhances carotenoid accumulation.These division factors likely alter carotenoid levels via their influence on chromoplast number and/or size.Taken together,our findings provide novel mechanistic insights into the machinery controlling chromoplast number and highlight a potential new strategy for enhancing carotenoid accumulation and nutritional value in food crops.

关 键 词：ARC3 CAROTENOID chromoplast number OR^His PARC6 PDV1 plastid division 

分 类 号：Q94[生物学—植物学]