Development and Carotenoid Synthesis in Dark-Grown Carrot Taproots Require PHYTOCHROME RAPIDLY REGULATED1

第一作者：Daniela Arias

第一单位：智利大学

通讯作者：Claudia Stange

 Abstarct 

背景回顾：Light stimulates carotenoid synthesis in plants during photomorphogenesis through the expression of PHYTOENE SYNTHASE (PSY), a key gene in carotenoid biosynthesis. The orange carrot (Daucus carota) synthesizes and accumulates high amounts of carotenoids in the taproot that grows underground. Contrary to other organs, light impairs carrot taproot development and represses the expression of carotenogenic genes, such as DcPSY1 and DcPSY2, reducing carotenoid accumulation. 

在光形态发生过程中，光通过刺激类胡萝卜素生物合成途径中关键基因PSY的表达，促进植物中类胡萝卜素的生物合成。橙色胡萝卜（Daucus carota）生长在地下的主根会合成并积累大量的类胡萝卜素。与其他器官相反，光对于胡萝卜主根的发育起负面影响，会抑制DcPSY1和DcPSY2等类胡萝卜素合成基因的表达，从而减少类胡萝卜素的积累。

前期基础：By means of RNA-seq, in a previous analysis we observed that carrot PHYTOCHROME RAPIDLY REGULATED1 (DcPAR1) is more highly expressed in the underground grown taproot compared to those grown in light. PAR1 is a transcriptional cofactor with a negative role in shade avoidance syndrome regulation in Arabidopsis (Arabidopsis thaliana) through the dimerization with PHYTOCHROME INTERACTING FACTORs (PIFs), allowing a moderate synthesis of carotenoids. 

在先前的RNA-seq分析中，作者发现胡萝卜的DcPAR1基因相比于地上部分组织，在地下生长的主根中表达量更高。PAR1是一种转录辅因子，通过与光敏色素互作因子PIF的二聚化，在拟南芥的避荫综合征调节中起负作用，保证类胡萝卜素的适度合成。

结果1-AtPAR1促进类胡萝卜素合成：Here, we show that overexpressing AtPAR1 in carrot increases carotenoid production in taproots grown underground as well as DcPSY1 expression. 

本文中，作者发现在胡萝卜中过度表达AtPAR1基因能够增加地下主根中类胡萝卜素的产生以及DcPSY1的表达。

结果2-DcPAR1与AtPAR1：The high expression of AtPAR1 and DcPAR1 led us to hypothesize a functional role of DcPAR1 that was verified through in vivo binding to AtPIF7 and overexpression in Arabidopsis, where AtPSY expression and carotenoid accumulation increased together with a photomorphogenic phenotype. 

介于AtPAR1和DcPAR1的高表达，我们假设DcPAR1具有与AtPAR1类似的功能，作者通过进一步体内与AtPIF7结合实验以及在拟南芥中的过表达试验进行了验证，发现拟南芥中AtPSY的表达和类胡萝卜素积累与光形态发生的表型一起被增强。

结果3-DCPAR1基因功能：Finally, DcPAR1 antisense carrot lines presented a dramatic decrease in carotenoid levels and in relative expression of key carotenogenic genes as well as impaired taproot development. 

最后，转DcPAR1反义的胡萝卜株系表现出类胡萝卜素含量和关键胡萝卜素生成基因表达量的显著降低，以及主根的发育受损。

结论：These results suggest that DcPAR1 is a key factor for secondary root development and carotenoid synthesis in carrot taproot grown underground.

这些结果表明，DcPAR1是胡萝卜地下主根的次生根发育和类胡萝卜素合成的关键调控因子。

doi: https://doi.org/10.1093/plphys/kiac097

Journal: Plant Physiology

Published date: March 10, 2022​