Plant Physiol:农科院景蕊莲研究团队发表小麦SBP-box基因功能和进化
2017年4月19日，国际植物学顶级期刊《plant Physiology》杂志上在线发表了中国农业科学院作物科学研究所作物基因资源发掘与利用创新团队景蕊莲研究员志题为“functional conservation and divergence among homoeologs of TaSPL20 and TaSPL21, two SBP-box genes governing yield-related traits in hexaploid wheat”的研究论文，研究发现普通小麦部分同源基因TaSPL20和TaSPL21在小麦长期的驯化和遗传改良过程中产生功能分化，其优异的自然变异在我国小麦育种进程中受到了定向选择并被广泛应用。研究生张斌、徐伟娜和刘霞为论文的共同第一作者，景蕊莲研究员为论文通讯作者。
植物Squamosa-promoter binding protein (SBP)-box基因亦称为SPL (Squamosa-promoter binding protein-like) 基因，是植物特有的一类转录因子。该基因家族不仅广泛参与植物开花、叶片和果实发育、株型建成，还参与GA信号转导等一系列过程，是典型的“一因多效”基因。
普通小麦是异源六倍体 (AABBDD)，经历了从二倍体到四倍体、四倍体到六倍体两次染色体加倍过程。多倍体化导致基因组发生部分重复，在长期选择进化过程中，重复的基因可能经历了不同的命运。小麦的多倍体特性以及丰富的遗传变异也使其能够适应多种多样的生长环境，因而成为人类的主要粮食作物之一。该团队研究发现，小麦SBP-box基因TaSPL20和TaSPL21分别位于小麦第七和第六同源群 (A、B和D基因组)，在小麦穗发育早期大量表达。异位表达TaSPL20和TaSPL21表明其蛋白功能相对保守，均具有调控穗部分枝和籽粒发育的功能。在小麦种质资源中，TaSPL20-7A/7D、TaSPL21-6A/6B/6D基因的调控区存在大量的自然变异，形成了多种单倍型。对其功能分析结果表明，在小麦长期的驯化和育种过程中位于不同染色体的部分同源基因TaSPL20和TaSPL21产生了功能分化，即基因沉默或功能变异。另外，研究鉴定出与株高和千粒重显著相关的优异等位变异，并在多年多点及旱胁迫和热胁迫等不同环境条件下进行了验证。由于这两个基因组合在重要农艺性状上具有较大的遗传效应，因此其优异单倍型在我国十大麦区均受到了不同程度的正向选择与应用。
原文链接：
Functional conservation and divergence among homoeologs of TaSPL20 and TaSPL21, two SBP-box GENEs governing yield-related traits in hexaploid wheat
原文摘要：
Maintaining high and stable yields has become an increasing challenge in wheat breeding due to climate change. Although Squamosa-promoter binding protein (SBP)-box genes have important roles in plant development, very little is known about the actual biological functions of wheat SBP-box family members. Here, we dissect the functional conservation, divergence and exploitation of homoeologs of two paralogous TaSPL wheat loci during domestication and breeding. TaSPL20 and TaSPL21 were highly expressed in the lemma and palea. Ectopic expressions of TaSPL20/21 in rice exhibited similar functions in terms of promoting panicle branching but had different functions during seed development. We characterized all six TaSPL20/21 genes located across the three homoeologous (A, B and D) genomes. According to the functional analysis of naturally occurring variants in 20 environments, four favorable haplotypes were identified. Together they reduced plant height by up to 27.5%, and TaSPL21-6D-HapII increased thousand grain weight by 9.73%. Our study suggests that TaSPL20 and TaSPL21 homoeologs underwent diversification in function with each evolving its own distinctive characteristics. During domestication and breeding of wheat in China, favorable haplotypes of each set were selected and exploited to varying degrees due to their large effects on plant height and 1000-grain weight.
作者：景蕊莲
