Production of Diploid Male Gametes in Arabidopsis by Cold-Induced Destabilization of Postmeiotic Radial Microtubule Arrays
Production of Diploid Male Gametes in Arabidopsis by Cold-Induced Destabilization of Postmeiotic Radial Microtubule Arrays
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DOI：
10.1104/pp.112.208611
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发表时间：
2012-12-01
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;Copenhaver, Gregory P.;Geelen, Danny
通过形成二倍体配子的全基因组复制是植物多倍体化、物种形成和多样化的主要途径。多倍体在不利气候条件下的流行使我们假设非生物胁迫条件可以诱导或刺激二倍体配子的产生。在这项研究中，我们表明，短时间的冷胁迫诱导拟南芥（拟南芥）的二倍体和多倍体花粉的生产。使用细胞学和遗传分析相结合，我们表明，冷应力改变了形成的放射状微管阵列在末期II，从而导致减数分裂后的胞质分裂和细胞壁形成的缺陷。因此，冷胁迫下的雄性减数分裂产生含有双核和多核小孢子的三联体、二联体和单联体。双核和多核小孢子的核融合在花粉有丝分裂Ⅰ前自发发生，最终形成二倍体和多倍体花粉粒。使用分离分析，我们还发现，大多数冷诱导的二分体和三分体在遗传上相当于第二次分裂恢复，并产生高度纯合的二倍体配子。从更广泛的角度来看，这些发现提供了对调节植物雄性配子发生的基本机制的见解，并证明了它们对环境胁迫的敏感性在多倍体化方面具有进化意义和农学意义。
Whole-genome duplication through the formation of diploid gametes is a major route for polyploidization, speciation, and diversification in plants. The prevalence of polyploids in adverse climates led us to hypothesize that abiotic stress conditions can induce or stimulate diploid gamete production. In this study, we show that short periods of cold stress induce the production of diploid and polyploid pollen in Arabidopsis (Arabidopsis thaliana). Using a combination of cytological and genetic analyses, we demonstrate that cold stress alters the formation of radial microtubule arrays at telophase II and consequently leads to defects in postmeiotic cytokinesis and cell wall formation. As a result, cold-stressed male meiosis generates triads, dyads, and monads that contain binuclear and polynuclear microspores. Fusion of nuclei in binuclear and polynuclear microspores occurs spontaneously before pollen mitosis I and eventually leads to the formation of diploid and polyploid pollen grains. Using segregation analyses, we also found that the majority of cold-induced dyads and triads are genetically equivalent to a second division restitution and produce diploid gametes that are highly homozygous. In a broader perspective, these findings offer insights into the fundamental mechanisms that regulate male gametogenesis in plants and demonstrate that their sensitivity to environmental stress has evolutionary significance and agronomic relevance in terms of polyploidization.