Cell Wall Invertase Is Essential for Ovule Development through Sugar Signaling Rather Than Provision of Carbon Nutrients1[OPEN]
Cell Wall Invertase Is Essential for Ovule Development through Sugar Signaling Rather Than Provision of Carbon Nutrients1[OPEN]
复制标题
DOI：
10.1104/pp.20.00400
复制
发表时间：
2020-07-01
期刊：
影响因子：
7.4
通讯作者：
Ruan, Yong-Ling
中科院分区：
文献类型：
--
作者：
Liao, Shengjin;Wang, Lu;Ruan, Yong-Ling
胚珠的形成决定着种子的数量，是实现作物产量的关键。然而，潜在的分子机制仍然难以捉摸。在这里，我们表明，细胞壁转化酶（CWIN）的功能作为一个积极的调节胚珠启动在拟南芥（拟南芥）。原位杂交结果表明，CWIN 2和CWIN 4在胚珠原基发生的胎座区表达。利用胚珠特异性SEEDSTICK启动子（pSTK）驱动的靶向人工microRNA沉默CWIN 2和CWIN 4，导致CWIN转录和活性显著降低，从而阻断胚珠启动，加重胚珠败育。在转基因株系中没有发现碳饥饿基因的诱导，用额外的碳补充新形成的花芽不能恢复胚珠表型。这表明抑制CWIN不会导致C饥饿。一组己糖转运蛋白在转基因植株中表达下调。其中，两个代表性的CWIN与CWIN 2和CWIN 4空间共表达，表明CWIN和己糖转运蛋白之间的耦合胚珠启动。RNA测序分析鉴定了编码推定的细胞外受体样激酶、MADS盒转录因子（包括STK）和响应CWIN-silencing的早期生长素响应基因的差异表达基因。我们的数据表明CWIN在胚珠启动中的重要作用，这是最有可能发生通过糖信号，而不是C营养的贡献。我们认为，CWIN-mediated糖信号可能被感知，并通过传递，己糖转运蛋白或受体样激酶调节胚珠的形成，通过调节下游生长素信号和MADS-box转录因子。胚珠特异性沉默的细胞壁转化酶抑制胚珠的启动中断糖信号，但不诱导碳饥饿。
Ovule formation is essential for realizing crop yield because it determines seed number. The underlying molecular mechanism, however, remains elusive. Here, we show that cell wall invertase (CWIN) functions as a positive regulator of ovule initiation in Arabidopsis (Arabidopsis thaliana). In situ hybridization revealed thatCWIN2andCWIN4were expressed at the placenta region where ovule primordia initiated. Specific silencing ofCWIN2andCWIN4using targeted artificial microRNA driven by an ovule-specific SEEDSTICK promoter (pSTK) resulted in a substantial reduction of CWIN transcript and activity, which blocked ovule initiation and aggravated ovule abortion. There was no induction of carbon (C) starvation genes in the transgenic lines, and supplementing newly forming floral buds with extra C failed to recover the ovule phenotype. This indicates that suppression of CWIN did not lead to C starvation. A group of hexose transporters was downregulated in the transgenic plants. Among them, two representative ones were spatially coexpressed withCWIN2andCWIN4, suggesting a coupling between CWIN and hexose transporters for ovule initiation. RNA-sequencing analysis identified differentially expressed genes encoding putative extracellular receptor-like kinases, MADS-box transcription factors, includingSTK, and early auxin response genes in response to CWIN-silencing. Our data demonstrate the essential role of CWIN in ovule initiation, which is most likely to occur through sugar signaling instead of C nutrient contribution. We propose that CWIN-mediated sugar signaling may be perceived by, and transmitted through, hexose transporters or receptor-like kinases to regulate ovule formation by modulating downstream auxin signaling and MADS-box transcription factors.Ovule-specific silencing of cell wall invertase inhibits initiation of the ovule by disrupting sugar signaling but without inducing carbon starvation.