The Arabidopsis Mutant jason Produces Unreduced First Division Restitution Male Gametes through a Parallel/Fused Spindle Mechanism in Meiosis II
The Arabidopsis Mutant jason Produces Unreduced First Division Restitution Male Gametes through a Parallel/Fused Spindle Mechanism in Meiosis II
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DOI：
10.1104/pp.110.170415
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发表时间：
2011-03-01
期刊：
影响因子：
7.4
通讯作者：
Geelen, Danny
中科院分区：
文献类型：
--
作者：
De Storme, Nico;Geelen, Danny
在植物中，全基因组加倍(多倍化)是一种广泛发生的过程，在很大程度上促进了植物的进化和多样化。二倍体配子的产生和融合被认为是植物多倍化的主要途径。减数分裂II MII纺锤体(PS)的平行排列或融合是产生三倍体后代的最常见机制之一。通过对拟南芥甲基磺酸乙酯的正向遗传学筛选，我们发现了拟南芥平行纺锤体1(AtPS1)，该基因是最近报道的与PS减数分裂缺陷相关的主效基因。此外，我们还描述了一个与植物雄配子体倍性调节有关的新等位基因Jason的分离和鉴定。与atps1突变体相似，Jason产生超过25%的2n花粉粒，并自发形成三倍体后代。通过结合细胞学和遗传学的方法，我们证明了Jason的丢失导致雄性MII中平行排列和融合的纺锤体的形成，导致未减少的第一分裂恢复2n孢子的产生。虽然Jason编码了一种功能未知的蛋白质，但我们另外证明了Jason的减数分裂PS缺陷是由AtPS1转录水平降低引起的，这表明Jason积极地调节AtPS1的表达，允许MII中中期酶II纺锤体的正确组织和定位。
In plants, whole-genome doubling (polyploidization) is a widely occurring process largely contributing to plant evolution and diversification. The generation and fusion of diploid gametes is now considered the major route of plant polyploidization. The parallel arrangement or fusion of meiosis II MII spindles (ps) is one of the most frequently reported mechanisms generating triploid offspring. Through a forward genetics screen of an Arabidopsis (Arabidopsis thaliana) ethyl methanesulfonate population, we identified Arabidopsis thaliana Parallel Spindles1 (AtPS1), which was recently reported as a major gene implicated in the control of the ps meiotic defect. In addition, we describe the isolation and characterization of a novel allele of JASON, involved in male gametophytic ploidy regulation in plants. Similar to atps1 mutants, jason produces more than 25% 2n pollen grains and spontaneously forms triploid offspring. By combining both cytological and genetic approaches, we demonstrate that loss of JASON causes the formation of parallel arranged and fused spindles in male MII, resulting in the production of unreduced first division restitution 2n spores. Although JASON encodes a protein of unknown function, we additionally show that the meiotic ps defect in jason is caused by a reduction in AtPS1 transcript levels, indicating that JASON positively regulates AtPS1 expression, allowing the proper organization and orientation of metaphase II spindle plates in MII.