Université de Toulouse, Institut National Polytechnique de Toulouse-Ecole Nationale Supérieure Agronomique, Unité Mixte de Recherche 990 Génomique et Biotechnologie des Fruits, Castanet-Tolosan, F-31326, France.
Institut National de la Recherche Agronomique, Unité Mixte de Recherche 990 Génomique et Biotechnologie des Fruits, Castanet-Tolosan, F-31326, France.
J Exp Bot. 2017 Oct 13;68(17):4869-4884. doi: 10.1093/jxb/erx303.
MADS-box transcription factors are key elements of the genetic networks controlling flower and fruit development. Among these, the class D clade gathers AGAMOUS-like genes which are involved in seed, ovule, and funiculus development. The tomato genome comprises two class D genes, Sl-AGL11 and Sl-MBP3, both displaying high expression levels in seeds and in central tissues of young fruits. The potential effects of Sl-AGL11 on fruit development were addressed through RNAi silencing and ectopic expression strategies. Sl-AGL11-down-regulated tomato lines failed to show obvious phenotypes except a slight reduction in seed size. In contrast, Sl-AGL11 overexpression triggered dramatic modifications of flower and fruit structure that include: the conversion of sepals into fleshy organs undergoing ethylene-dependent ripening, a placenta hypertrophy to the detriment of locular space, starch and sugar accumulation, and an extreme softening that occurs well before the onset of ripening. RNA-Seq transcriptomic profiling highlighted substantial metabolic reprogramming occurring in sepals and fruits, with major impacts on cell wall-related genes. While several Sl-AGL11-related phenotypes are reminiscent of class C MADS-box genes (TAG1 and TAGL1), the modifications observed on the placenta and cell wall and the Sl-AGL11 expression pattern suggest an action of this class D MADS-box factor on early fleshy fruit development.
MADS 框转录因子是控制花和果实发育的遗传网络的关键元素。其中，D 类簇汇集了 AGAMOUS 样基因，这些基因参与种子、胚珠和珠柄的发育。番茄基因组包含两个 D 类基因，Sl-AGL11 和 Sl-MBP3，它们在种子和幼果的中央组织中都显示出高表达水平。通过 RNAi 沉默和异位表达策略研究了 Sl-AGL11 对果实发育的潜在影响。Sl-AGL11 下调的番茄品系除了种子大小略有减少外，没有表现出明显的表型。相比之下，Sl-AGL11 的过表达触发了花和果实结构的剧烈改变，包括：萼片转化为肉质器官，经历乙烯依赖性成熟，胎座肥大，损害腔室空间，淀粉和糖积累，以及在成熟开始之前发生的极度软化。RNA-Seq 转录组谱分析突出了在萼片和果实中发生的大量代谢重编程，对细胞壁相关基因有重大影响。虽然几个 Sl-AGL11 相关表型类似于 C 类 MADS 框基因（TAG1 和 TAGL1），但在胎座和细胞壁上观察到的修饰以及 Sl-AGL11 的表达模式表明，这种 D 类 MADS 框因子对早期肉质果实发育有作用。
