Transcription factor CsTT8 promotes fruit coloration by positively regulating the methylerythritol 4-phosphate pathway and carotenoid biosynthesis pathway in citrus (Citrus spp.)  

作　　者：Quan Sun Zhengchen He Ranran Wei Yingzi Yin Junli Ye Lijun Chai Zongzhou Xie Wenwu Guo Juan Xu Yunjiang Cheng Qiang Xu Xiuxin Deng 

机构地区：[1]National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops,Huazhong Agricultural University,Wuhan 430070,China [2]National Research Center for Apple Engineering and Technology,Shandong Agricultural University,Taian,Shandong 271018,China [3]Hubei Hongshan Laboratory Wuhan,Hubei 430070,China

出　　处：《Horticulture Research》2023年第11期71-81,共11页园艺研究（英文）

基　　金：supported by the National Natural Science Foundation of China(No.31930095,32172527);the Modern Agro-industry Technology Research System(CARS-26).

摘　　要：Carotenoids directly influence citrus fruit color and nutritional value,which is critical to consumer acceptance.Elucidating the potential molecular mechanism underlying carotenoid metabolism is of great importance for improving fruit quality.Despite the well-established carotenoid biosynthetic pathways,the molecular regulatory mechanism underlying carotenoid metabolism remains poorly understood.Our previous studies have reported that the Myc-type basic helix-loop-helix(bHLH)transcription factor(TF)regulates citrus proanthocyanidin biosynthesis.Transgenic analyses further showed that overexpression of CsTT8 could significantly promote carotenoid accumulation in transgenic citrus calli,but its regulatory mechanism is still unclear.In the present study,we found that overexpression of CsTT8 enhances carotenoid content in citrus fruit and calli by increasing the expression of CsDXR,CsHDS,CsHDR,CsPDS,CsLCYE,CsZEP,and CsNCED2,which was accompanied by changes in the contents of abscisic acid and gibberellin.The in vitro and in vivo assays indicated that CsTT8 directly bound to the promoters of CsDXR,CsHDS,and CsHDR,the keymetabolic enzymes of the methylerythritol 4-phosphate(MEP)pathway,thus providing precursors for carotenoid biosynthesis and transcriptionally activating the expression of these three genes.In addition,CsTT8 activated the promoters of four key carotenoid biosynthesis pathway genes,CsPDS,CsLCYE,CsZEP,and CsNCED2,directly promoting carotenoid biosynthesis.This study reveals a novel network of carotenoid metabolism regulated by CsTT8.Our findings will contribute to manipulating carotenoid metabolic engineering to improve the quality of citrus fruit and other crops.

关 键 词：CITRUS CITRUS METABOLISM 

分 类 号：S666.2[农业科学—果树学]