Department of Agricultural Sciences, University of Naples Federico II, Portici, 80055, Italy.
Sci Rep. 2019 Mar 6;9(1):3699. doi: 10.1038/s41598-019-40142-3.
Carotenoid accumulation in tomato (Solanum lycopersicum) fruits is influenced by environmental stimuli and hormonal signals. However, information on the relative regulatory mechanisms are scanty since many molecular players of the carotenoid biosynthetic pathway are still unknown. Here, we reported a basic Helix-Loop-Helix transcription factor, named SlARANCIO (SlAR), whose silencing influences carotenoid accumulation in tomato fruits. The SlAR gene was found in the S. pennellii introgression line (IL) 12-4SL that holds the carotenoid QTL lyc12.1. We observed that the presence of the wild region in a cultivated genetic background led to a decrease in total carotenoid content of IL12-4SL fruits. To get insights into the function of SlAR, a quick reverse genetic approach was carried out. Virus-induced gene silencing of SlAR in S. lycopersicum M82 and MicroTom fruits reproduced the same phenotype observed in IL12-4SL, i.e. decreased content of lycopene and total carotenoids. Vice versa, the overexpression of SlAR in Nicotiana benthamiana leaves increased the content of total carotenoids and chlorophylls. Our results, combined with public transcriptomic data, highly suggest that SlAR acts indirectly on the carotenoid pathway and advances current knowledge on the molecular regulators controlling lyc12.1 and, potentially, precursors of carotenoid biosynthesis.
类胡萝卜素在番茄（Solanum lycopersicum）果实中的积累受环境刺激和激素信号的影响。然而，由于许多类胡萝卜素生物合成途径的分子参与者仍然未知，关于相对调控机制的信息仍然很少。在这里，我们报道了一个基本的螺旋-环-螺旋转录因子，命名为 SlARANCIO（SlAR），其沉默会影响番茄果实中的类胡萝卜素积累。SlAR 基因在含有类胡萝卜素 QTL lyc12.1 的 S. pennellii 导入系（IL）12-4SL 中被发现。我们观察到，在栽培遗传背景中存在野生区域会导致 IL12-4SL 果实中总类胡萝卜素含量降低。为了深入了解 SlAR 的功能，我们采用了快速反向遗传学方法。在 S. lycopersicum M82 和 MicroTom 果实中，SlAR 的病毒诱导基因沉默再现了在 IL12-4SL 中观察到的相同表型，即番茄红素和总类胡萝卜素含量降低。反之，在 Nicotiana benthamiana 叶片中过表达 SlAR 会增加总类胡萝卜素和叶绿素的含量。我们的结果，结合公共转录组数据，强烈表明 SlAR 间接作用于类胡萝卜素途径，并推进了关于调控 lyc12.1 及其潜在的类胡萝卜素生物合成前体的分子调节剂的现有知识。
