Plant Physiol:中科院作物所毛龙研究组小麦幼穗发育基因调控网络
2017年5月17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毛龙研究员领衔的“作物生物信息与应用”创新团队在小麦幼穗发育基因调控网络解析研究中取得新进展。研究工作系统研究小麦幼穗发育早期四个决定后期穗粒数重要阶段基因表达的差异，解释了这一重要时期基因表达调控的特点。作科所博士研究生冯楠和宋高原为该论文共同第一作者，作科所毛龙研究员和李爱丽研究员为共同通讯作者。
据悉，小麦穗的发育经历二棱期、小穗发育期、小花发育期、小花成熟期等关键时期。其中，二棱期是小穗发育初始时期，决定小穗原基的多少;小穗发育期是小花原基形成的时期，决定小花数目的多少;小花发育期则决定小花原基能否成功发育成小花，而小花成熟期是雌雄蕊发育期，决定小花的育性。小麦的每个小穗能产生多到8个以上的小花原基;但最后只有3-4个能够发育生成籽粒。因此，小麦穗发育的早期状态直接影响小麦的最终产量。但是，迄今为止，人们对该过程中的基因调控及网络却知之不多。
“作物生物信息与应用”创新团队利用生物信息手段，通过对小麦幼穗发育早期的转录组分析发现该过程中小麦基因表达活跃、表达模式多样。根据基因表达的聚类分析和使其特异阶段的重要基因挖掘，发现了大量与幼穗发育相关的重要转录因子。其中，很多与模式植物如水稻的调控基因保守。该团队同时对小麦幼穗的小分子RNA进行了分析，发现重要小分子RNA如miR159、miR167、miR319、miR396等高度表达，与其靶基因的表达模式协同，并能进行有效切割、调控。为了证明他们的分析结果的可靠性，该团队对其中一个在小花发育期高表达的基因AGO1d进行了突变体分析。该基因在花药的绒粘层特异表达;突变后使小麦的可育花粉数目大大下降，严重影响后期的每穗籽粒数。这一工作表明，转录组分析发现的调控基因在小麦花序的发育过程中发挥重要的作用。这些候选基因可为今后分子育种中开发分子标记和进行遗传操作提供重要的信息。
这一工作是继该团队今年年初在《Nature Communication》上发表了小麦模式植物二穗短柄草开花时间可变剪切分子机制后的又一个重要工作。Nat Commun:浙大武亮研究组和农科院毛龙研究组合作揭示作物开花分子调控机制
原文链接：
Transcriptome of wheat inflorescence development from spikelet initiation to floral patterning
原文摘要：
Early reproductive development in cereals is crucial for final grain number per spike, and hence the yield potential of the crop. To date, however, no systematic analyses of gene expression profiles during this important process have been conducted for common wheat (Triticum aestivum). Here, we studied the transcriptome profiles at four stages of early wheat reproductive development, from spikelet initiation to floral organ differentiation. K-means clustering and stage-specific transcript identification detected dynamically expressed homoeologs of important transcription regulators in spikelet and floral meristems that may be involved in spikelet initiation, floret meristem specification, and floral organ patterning, as inferred from their homologs in model plants. Small RNA transcriptome sequencing discovered key microRNAs that were differentially expressed during wheat inflorescence development alongside their target genes, suggesting that miRNA-mediated regulatory mechanisms for floral development may be conserved in cereals and Arabidopsis. Our analysis was further substantiated by the functional characterization of the ARGONAUTE 1d (AGO1d) gene, which was initially expressed in stamen primordia and later in the tapetum during anther maturation. In agreement with its stage-specific expression pattern, the loss of function of the predominantly expressed B homoeolog of AGO1d in a tetraploid durum wheat mutant resulted in smaller anthers with more infertile pollens than the wild type, and a reduced grain number per spike. Together, our work provides a first glimpse of the gene regulatory networks in wheat inflorescence development that may be pivotal for floral and grain development, highlighting potential targets for genetic manipulation to improve future wheat yields.
作者：毛龙
