TOMATO AGAMOUS-LIKE 1 is a component of the fruit ripening regulatory network
TOMATO AGAMOUS-LIKE 1 is a component of the fruit ripening regulatory network
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DOI：
10.1111/j.1365-313x.2009.04064.x
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发表时间：
2009-12-01
期刊：
影响因子：
7.2
通讯作者：
Aharoni, Asaph
中科院分区：
文献类型：
--
作者：
Itkin, Maxim;Seybold, Heike;Aharoni, Asaph
受精后，肉质果实的心皮扩张经历一个阶段性变化，直至成熟。虽然乙烯信号在介导跃变型成熟中的作用已经确立，但关于乙烯生物合成的调节及其与果实发育程序的关联的知识仍然缺乏。番茄转录因子的功能筛选表明，番茄AGAMOUS样1（TAGL1）MADS盒基因的沉默导致果实色素沉着改变。过量表达TAGL1作为嵌合阻遏物建议在控制成熟中的作用，因为转基因番茄果实表现出降低的类胡萝卜素和乙烯水平，抑制叶绿素分解，并下调成熟相关基因。此外，过量表达TAGL1的果实积累了更多的番茄红素，并且它们的萼片肿胀，积累了高水平的黄色类黄酮柚皮素查耳酮并含有番茄红素。瞬时启动子结合试验表明，在成熟的TAGL 1活性的一部分是通过直接激活的ACS 2，乙烯生物合成基因，最近被报道为RIN MADS盒因子的目标。对TAGL 1转录本及其在rin突变背景下的过表达的检查表明，RIN不调节TAGL 1，反之亦然。结果还表明，由TAGL1调节的RIN依赖性和非依赖性过程。我们还注意到，TAGL1功能丧失系的果实具有薄的果皮层，表明TAGL1在成熟前心皮扩张中的额外作用。这些结果为目前控制肉质果实成熟及其与乙烯生物合成途径相关的调控网络模型增加了一个新的组成部分。
P>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, indicating an additional role for TAGL1 in carpel expansion prior to ripening. The results add a new component to the current model of the regulatory network that controls fleshy fruit ripening and its association with the ethylene biosynthesis pathway.