Tang Ning, Deng Wei, Hu Guojian, Hu Nan, Li Zhengguo
Genetic Engineering Research Center, School of Life Sciences, Key Laboratory of Functional Gene and New Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing University, Chongqing 400030, China.
PLoS One. 2015 Apr 24;10(4):e0125355. doi: 10.1371/journal.pone.0125355. eCollection 2015.
Fruit set is a key process for crop production in tomato which occurs after successful pollination and fertilization naturally. However, parthenocarpic fruit development can be uncoupled from fertilization triggered by exogenous auxin or gibberellins (GAs). Global transcriptome knowledge during fruit initiation would help to characterize the molecular mechanisms by which these two hormones regulate pollination-dependent and -independent fruit set.
In this work, digital gene expression tag profiling (DGE) technology was applied to compare the transcriptomes from pollinated and 2, 4-D/GA3-treated ovaries. Activation of carbohydrate metabolism, cell division and expansion as well as the down-regulation of MADS-box is a comprehensive regulatory pathway during pollination-dependent and parthenocarpic fruit set. The signaling cascades of auxin and GA are significantly modulated. The feedback regulations of Aux/IAAs and DELLA genes which functioned to fine-tune auxin and GA response respectively play fundamental roles in triggering fruit initiation. In addition, auxin regulates GA synthesis via up-regulation of GA20ox1 and down-regulation of KNOX. Accordingly, the effect of auxin on fruit set is mediated by GA via ARF2 and IAA9 down-regulation, suggesting that both pollination-dependent and parthenocarpic fruit set depend on the crosstalk between auxin and GA.
This study characterizes the transcriptomic features of ovary development and more importantly unravels the integral roles of auxin and GA on pollination-dependent and parthenocarpic fruit set.
坐果是番茄作物生产中的一个关键过程，自然情况下它发生在成功授粉和受精之后。然而，单性结实果实的发育可以与由外源生长素或赤霉素（GAs）引发的受精过程解偶联。果实起始阶段的全球转录组知识将有助于表征这两种激素调节授粉依赖型和非授粉依赖型坐果的分子机制。
在这项研究中，应用数字基因表达标签谱分析（DGE）技术比较了授粉的和经2,4-D/GA3处理的子房的转录组。碳水化合物代谢、细胞分裂和扩展的激活以及MADS-box的下调是授粉依赖型和单性结实坐果过程中的一条综合调控途径。生长素和GA的信号级联被显著调节。分别对生长素和GA反应起到微调作用的Aux/IAAs和DELLA基因的反馈调节在触发果实起始中发挥着基本作用。此外，生长素通过上调GA20ox1和下调KNOX来调节GA合成。相应地，生长素对坐果的影响是通过GA介导的ARF2和IAA9下调来实现的，这表明授粉依赖型和单性结实坐果都依赖于生长素和GA之间的相互作用。
本研究表征了子房发育的转录组特征，更重要的是揭示了生长素和GA在授粉依赖型和单性结实坐果中的整体作用。
