High expression of VRT2 increases the number of rudimentary basal spikelets in wheat
High expression of VRT2 increases the number of rudimentary basal spikelets in wheat
复制标题
VRT2的高表达增加了小麦中未发育基部小穗的数量
DOI：
10.1101/2021.08.03.454952
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Backhaus A
中科院分区：
文献类型：
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作者：
Backhaus A
小穗是禾本科花序的基本构件，其发育和分枝模式决定了禾本科牧草不同的花序结构和产量。在小麦中，中央小穗产生最多和最大的籽粒，而小穗大小在纵向和基面上逐渐减小，形成小麦特有的披针形穗形。顶瓣梯度与小穗的发育年龄有关，但基生小穗首先发育，其体积小、发育不全的原因尚不清楚。在这里，我们采用了G&T-seq，一种低输入的转录组学方法，来描述在披针形形状建立之前和之后单个穗的空间部分内的基因表达谱。我们观察到单个穗的顶端、中央和基底部之间的基因表达谱比属于连续发育时间点的任何部分之间的差异更大。我们发现，包括VRT-A2在内的SVP MADS-box转录因子在小麦穗的基底部表达最高，并且表现出与开花E类SEP1基因相反的表达梯度。基于多年的田间试验和转基因品系，我们发现VRT-A2在穗部的高表达与基本小穗数量的增加有关。我们的结果得到了计算模型的支持，表明基本小穗从营养发育程序到花发育程序的延迟过渡导致了小麦穗的披针形。这项研究强调了空间分辨转录组学的价值，以获得对禾本科花序发育遗传学途径的新见解。
Spikelets are the fundamental building blocks of Poaceae inflorescences and their development and branching patterns determine the various inflorescence architectures and grain yield of grasses. In wheat, the central spikelets produce the most and largest grains, while spikelet size gradually decreases acro-and basipetally, giving rise to the characteristic lanceolate shape of wheat spikes. The acropetal gradient correlates with the developmental age of spikelets, however the basal spikelets are developed first and the cause of their small size and rudimentary development is unclear. Here, we adapted G&T-seq, a low-input transcriptomics approach, to characterise gene expression profiles within spatial sections of individual spikes before and after the establishment of the lanceolate shape. We observed larger differences in gene expression profiles between the apical, central and basal sections of a single spike than between any section belonging to consecutive developmental timepoints. We found that SVP MADS-box transcription factors, including VRT-A2, are expressed highest in the basal section of the wheat spike and display the opposite expression gradient to flowering E-class SEP1 genes. Based on multi-year field trials and transgenic lines, we show that higher expression of VRT-A2 in the basal sections of the spike is associated with increased numbers of rudimentary basal spikelets. Our results, supported by computational modelling, suggest that the delayed transition of basal spikelets from vegetative to floral developmental programmes results in the lanceolate shape of wheat spikes. This study highlights the value of spatially resolved transcriptomics to gain new insights into developmental genetics pathways of grass inflorescences.