Polyploidization mechanisms: temperature environment can induce diploid gamete formation in Rosa sp.
Polyploidization mechanisms: temperature environment can induce diploid gamete formation in Rosa sp.
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DOI：
10.1093/jxb/err052
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发表时间：
2011-06-01
影响因子：
6.9
通讯作者：
Le Bris, Manuel
中科院分区：
文献类型：
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作者：
Pecrix, Yann;Rallo, Geraldine;Le Bris, Manuel
多倍体是一种重要的进化现象，但多倍体产生的机制仍未得到充分探索。多倍化可能存在环境因素。本研究旨在阐明温度如何促进二倍体配子的形成，二倍体配子的形成被认为是有性多倍体化的基本要素。首先，对小孢子发生和小配子发生进行了详细的细胞学分析，以精确定位对温度最敏感的关键发育阶段。然后，通过高温梯度的阐述，分析了热诱导的孢子和花粉特征的改变。蔷薇植物对高温敏感，发育敏感窗口仅限于减数分裂。而且，有效温度范围实际上很窄。减数分裂早期的 36 摄氏度导致花粉活力下降、花粉外壁缺陷，尤其是大量二倍体花粉粒的出现。它们是由二联体或三联体产生的，主要是在末期 II 热诱导纺锤体定向错误后形成的。高温环境有可能提高配子倍性水平。在某些极端温度下获得的高频率双配子支持了多倍化事件可能在不利条件下发生的假设，并表明多倍化在全球变化背景下得到促进。
Polyploidy is an important evolutionary phenomenon but the mechanisms by which polyploidy arises still remain underexplored. There may be an environmental component to polyploidization. This study aimed to clarify how temperature may promote diploid gamete formation considered an essential element for sexual polyploidization. First of all, a detailed cytological analysis of microsporogenesis and microgametogenesis was performed to target precisely the key developmental stages which are the most sensitive to temperature. Then, heat-induced modifications in sporad and pollen characteristics were analysed through an exposition of high temperature gradient. Rosa plants are sensitive to high temperatures with a developmental sensitivity window limited to meiosis. Moreover, the range of efficient temperatures is actually narrow. 36 degrees C at early meiosis led to a decrease in pollen viability, pollen ectexine defects but especially the appearance of numerous diploid pollen grains. They resulted from dyads or triads mainly formed following heat-induced spindle misorientations in telophase II. A high temperature environment has the potential to increase gamete ploidy level. The high frequencies of diplogametes obtained at some extreme temperatures support the hypothesis that polyploidization events could have occurred in adverse conditions and suggest polyploidization facilitating in a global change context.