Liu Bing, De Storme Nico, Geelen Danny
Department of Plant Production, Faculty of Bioscience Engineering, University of Ghent, Ghent, Belgium.
School of Integrative Plant Science, Cornell University, Ithaca, NY, United States.
Front Plant Sci. 2018 Feb 5;9:91. doi: 10.3389/fpls.2018.00091. eCollection 2018.
Short periods of cold stress induce male meiotic restitution and diploid pollen formation in by specifically interfering with male meiotic cytokinesis. Similar alterations in male meiotic cell division and gametophytic ploidy stability occur when gibberellic acid (GA) signaling is perturbed in developing anthers. In this study, we found that exogenous application of GA primarily induces second division restitution (SDR)-type pollen in Arabidopsis, similar to what cold does. Driven by the close similarity in cellular defects, we tested the hypothesis that cold-induced meiotic restitution is mediated by GA-DELLA signaling. Using a combination of chemical, genetic and cytological approaches, however, we found that both exogenously and endogenously altered GA signaling do not affect the cold sensitivity of male meiotic cytokinesis. Moreover, localization study using a GFP-tagged version of RGA protein revealed that cold does not affect the expression pattern and abundance of DELLA in Arabidopsis anthers at tetrad stage. Expression study found that transcript of appears enhanced in cold-stressed young flower buds. Since our previous work demonstrated that loss of function of DELLA causes irregular male meiotic cytokinesis, we here conclude that cold-induced meiotic restitution is not mediated by DELLA-dependent GA signaling.
短时间的冷胁迫通过特异性干扰雄配子减数分裂胞质分裂，诱导拟南芥雄配子减数分裂恢复和二倍体花粉形成。当发育中的花药中赤霉素（GA）信号受到干扰时，雄配子减数分裂细胞分裂和配子体倍性稳定性会发生类似变化。在本研究中，我们发现外源施加GA主要诱导拟南芥中第二分裂恢复（SDR）型花粉，这与冷胁迫的作用类似。受细胞缺陷方面的密切相似性驱动，我们测试了冷诱导减数分裂恢复由GA-DELLA信号介导这一假设。然而，通过化学、遗传和细胞学方法相结合，我们发现外源和内源改变的GA信号均不影响雄配子减数分裂胞质分裂的冷敏感性。此外，使用RGA蛋白的绿色荧光蛋白（GFP）标记版本进行的定位研究表明，冷胁迫不影响四分体阶段拟南芥花药中DELLA的表达模式和丰度。表达研究发现，在冷胁迫的幼嫩花芽中，[此处原文缺失相关基因名称]的转录本有所增强。由于我们之前的研究表明DELLA功能丧失会导致雄配子减数分裂胞质分裂异常，因此我们在此得出结论，冷诱导的减数分裂恢复不是由依赖DELLA的GA信号介导的。
