TaIAA21 represses TaARF25-mediated expression of TaERFs required for grain size and weight development in wheat
TaIAA21 represses TaARF25-mediated expression of TaERFs required for grain size and weight development in wheat
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DOI：
10.1111/tpj.15541
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发表时间：
2021-11-10
期刊：
影响因子：
7.2
通讯作者：
Li, Aili
中科院分区：
文献类型：
--
作者：
Jia, Meiling;Li, Yanan;Li, Aili
生长素信号对籽粒大小和粒重的发育是必不可少的，这是作物产量的两个重要组成部分。然而，没有生长素/吲哚乙酸抑制因子(AUX/IAA)参与小麦(Triticum aestivum L.)到目前为止的谷物。在此，我们克隆了小麦AUX/IAA基因TaIAA21，并对其调控途径进行了研究。我们发现TaIAA21突变显著增加了粒长、粒宽和粒重。突变籽粒的横切面显示，与野生型相比，外果皮细胞拉长，其中TaIAA21的表达是通过原位杂交检测的。对在发育早期籽粒中高表达的生长素反应因子(ARF)基因的筛选表明，TaARF25与TaIAA21相互作用。相反，四倍体小麦ARF25基因突变显著降低了籽粒大小和重量。RNA测序分析表明，在taaa21突变体中，几个乙烯反应因子基因(ERF)在其启动子中携带生长素反应顺式元件而上调。其中ERF3在taaa21突变体中上调，在ttarf25突变体中下调。反式激活分析表明，ARF25促进了ERF3的转录，而TtERF3的突变导致了颗粒尺寸和重量的减小。自然变异分析确定了三种TaIAA21-A单倍型，其等位基因频率在品种中相对于地方品种增加，这是育种选择的标志。我们的工作表明，TaIAA21通过ARF25-ERFS模块作为籽粒大小和重量发育的负调控因子，对小麦产量的提高是有用的。
Auxin signaling is essential for the development of grain size and grain weight, two important components for crop yield. However, no auxin/indole acetic acid repressor (Aux/IAA) has been functionally characterized to be involved in the development of wheat (Triticum aestivum L.) grains to date. Here, we identified a wheat Aux/IAA gene, TaIAA21, and studied its regulatory pathway. We found that TaIAA21 mutation significantly increased grain length, grain width, and grain weight. Cross-sections of mutant grains revealed elongated outer pericarp cells compared to those of the wild type, where the expression of TaIAA21 was detected by in situ hybridization. Screening of auxin response factor (ARF) genes highly expressed in early developing grains revealed that TaARF25 interacts with TaIAA21. In contrast, mutation of the tetraploid wheat (Triticum turgidum) ARF25 gene significantly reduced grain size and weight. RNA sequencing analysis revealed upregulation of several ethylene response factor genes (ERFs) in taiaa21 mutants which carried auxin response cis-elements in their promoter. One of them, ERF3, was upregulated in the taiaa21 mutant and downregulated in the ttarf25 mutant. Transactivation assays showed that ARF25 promotes ERF3 transcription, while mutation of TtERF3 resulted in reduced grain size and weight. Analysis of natural variations identified three TaIAA21-A haplotypes with increased allele frequencies in cultivars relative to landraces, a signature of breeding selection. Our work demonstrates that TaIAA21 works as a negative regulator of grain size and weight development via the ARF25-ERFs module and is useful for yield improvement in wheat.