TOMATO AGAMOUS‐LIKE 1 is a component of the fruit ripening regulatory network

作者：Maxim Itkin, Heike Seybold, Dario Breitel, Ilana Rogachev, Sagit Meir, Asaph Aharoni · 发表于：The Plant Journal · 年份：2009 · DOI：10.1111/j.1365-313x.2009.04064.x · 被引用次数：377 · 研究领域：Postharvest Quality and Shelf Life Management、Plant Physiology and Cultivation Studies、Plant Gene Expression Analysis

After fertilization, the expanding carpel of fleshy fruit goes through a phase change to ripening. Although the role of ethylene signalling in mediating climacteric ripening has been established, knowledge regarding the regulation of ethylene biosynthesis and its association with fruit developmental programs is still lacking. A functional screen of tomato transcription factors showed that silencing of the TOMATO AGAMOUS-LIKE 1 (TAGL1) MADS box gene results in altered fruit pigmentation. Over-expressing TAGL1 as a chimeric repressor suggested a role in controlling ripening, as transgenic tomato fruit showed reduced carotenoid and ethylene levels, suppressed chlorophyll breakdown, and down-regulation of ripening-associated genes. Moreover, fruits over-expressing TAGL1 accumulated more lycopene, and their sepals were swollen, accumulated high levels of the yellow flavonoid naringenin chalcone and contained lycopene. Transient promoter-binding assays indicated that part of the TAGL1 activity in ripening is executed through direct activation of ACS2, an ethylene biosynthesis gene that has recently been reported to be a target of the RIN MADS box factor. Examination of the TAGL1 transcript and its over-expression in the rin mutant background suggested that RIN does not regulate TAGL1 or vice versa. The results also indicated RIN-dependent and -independent processes that are regulated by TAGL1. We also noted that fruit of TAGL1 loss-of-function lines had a thin pericarp layer, indic...