南湖新闻网讯（通讯员 张祖新）近日，我校玉米团队张祖新教授和美国加州大学伯克利分校Sarah Hake教授合作，揭示了Fascicled ear1(Fas1)位点两个基因的拷贝数变异调控玉米花序分生组织细胞命运和花序分生组织中心-外缘轴极性分化的生物学功能。相关研究成果发表在《美国国家科学院院刊》(Proceedings of the National Academy of Sciences of the United States of America)上。

植物分生组织是一团自我更新的多能干细胞群体，通过固有模式持续分化产生侧生器官。辐射对称的花序原基如何产生不对称的侧生器官是植物发育生物学领域的共性科学问题。栽培玉米的雄花序有一个主轴和多分枝，雌花序只有一个穗轴、无分枝。Fas1是一个雌、雄花序无主轴、多分枝的显性突变体。研究发现，该位点的基因重排导致了MADS-box家族转录因子zmm8和YABBY家族转录因子drl2的拷贝数增加，并由此产生新的启动子使得zmm8和drl2在花序分生组织原基异位表达，通过下调分生组织中心轴基因的表达抑制中部细胞增殖，同时上调外围轴基因的表达促进外围细胞增殖，最终形成花序主轴缺失、分枝增多的雌、雄花序。该研究结果说明了花序分生组织原基中严格的基因时空表达模式的重要性，也为基因拷贝数变异影响花序发育提供了新证据。

论文链接：https://www.pnas.org/content/118/7/e2019218118

英文摘要：Plant meristems are self-renewing groups of pluripotent stem cells that produce lateral organs in a stereotypical pattern. Of interest is how the radially symmetrical meristem produces laminar lateral organs. Both the male and female inflorescence meristems of the dominantFascicled ear(Fas1) mutant fail to grow as a single point and instead show deep branching. Positional cloning of two independentFas1alleles identified an ∼160 kb region containing two floral genes, theMADS-boxgene,zmm8, and theYABBYgene,drooping leaf2(drl2). Both genes are duplicated within theFas1locus and spatiotemporally misexpressed in the mutant inflorescence meristems. Increasedzmm8expression alone does not affect inflorescence development; however, combined misexpression ofzmm8,drl2, and their syntenic paralogszmm14anddrl1, perturbs meristem organization. We hypothesize that misexpression of the floral genes in the inflorescence and their potential interaction cause ectopic activation of a laminar program, thereby disrupting signaling necessary for maintenance of radially symmetrical inflorescence meristems. Consistent with this hypothesis, RNA sequencing and in situ analysis reveal altered expression patterns of genes that define distinct zones of the meristem and developing leaf. Our findings highlight the importance of strict spatiotemporal patterns of expression for bothzmm8anddrl2and provide an example of phenotypes arising from tandem gene duplications.

审核人：严建兵