Abstract：
Carotenoids are important pigmented nutrients synthesized by tomato fruits during ripening. To reveal the molecular mechanism underlying carotenoid synthesis during tomato fruit ripening, we analyzed carotenoid metabolites and transcriptomes in six development stages of tomato fruits. A total of thirty different carotenoids were detected and quantified in tomato fruits from 10 to 60 DPA. Based on differential gene expression profiles and WGCNA, we explored several genes that were highly significant and negatively correlated with lycopene, all of which encode fasciclin-like arabinogalactan proteins (FLAs). The FLAs are involved in plant signal transduction, however the functional role of these proteins has not been studied in tomato. Genome-wide analysis revealed that cultivated and wild tomato species contained 18 to 22 FLA family members, clustered into four groups, and mainly evolved by means of segmental duplication. The functional characterization of FLAs showed that silencing of SlFLA1, 5, and 13 were found to contribute to the early coloration of tomato fruits, and the expression of carotenoid synthesis-related genes was up-regulated in fruits that changed phenotypically, especially in SlFLA13-silenced plants. Furthermore, the content of multiple carotenoids (including (E/Z)-phytoene, lycopene, γ-carotene, and α-carotene) was significantly increased in SlFLA13-silenced fruits, suggesting that SlFLA13 has a potential inhibitory function in regulating carotenoid synthesis in tomato fruits. The results of the present study broaden the idea of analyzing the biological functions of tomato FLAs and preliminary evidence for the inhibitory role of SlFLA13 in carotenoid synthesis in fruit, providing the theoretical basis and a candidate for improving tomato fruit quality.
摘要：
类胡萝卜素是番茄果实成熟过程中合成的重要色素营养素。为揭示番茄果实成熟过程中类胡萝卜素合成的分子机制,我们分析了番茄果实六个发育阶段的类胡萝卜素代谢产物和转录组。在10至60DPA的番茄果实中检测并定量了总共30种不同的类胡萝卜素。基于差异基因表达谱和WGCNA,我们探索了几个与番茄红素高度显著且负相关的基因，所有这些编码fasciclin样阿拉伯半乳聚糖蛋白（FLA）。FLA参与植物信号转导,然而，这些蛋白质的功能作用尚未在番茄中进行研究。全基因组分析表明，栽培和野生番茄物种包含18至22个FLA家族成员，分为四组，主要通过分段复制进化。FLA的功能表征表明，发现SlFLA1，5和13的沉默有助于番茄果实的早期着色，类胡萝卜素合成相关基因的表达在表型改变的水果中上调，尤其是在SlFLA13沉默的植物中。此外，多类胡萝卜素的含量(包括(E/Z)-八烯，番茄红素,γ-胡萝卜素,和α-胡萝卜素）在SlFLA13沉默的果实中显著增加，这表明SlFLA13具有潜在的抑制番茄果实类胡萝卜素合成的作用。本研究的结果拓宽了分析番茄FLA生物学功能的思路，初步证明了SlFLA13对果实类胡萝卜素合成的抑制作用，为改善番茄果实品质提供理论依据和候选。
