Department of Cell Biology and Plant Biochemistry, University of Regensburg, 93053 Regensburg, Germany.
Department for Biochemistry I, Biochemistry Centre, University of Regensburg, 93053 Regensburg, Germany.
Plant Physiol. 2024 Jun 28;195(3):2111-2128. doi: 10.1093/plphys/kiae087.
For successful double fertilization in flowering plants (angiosperms), pollen tubes deliver 2 nonmotile sperm cells toward female gametes (egg and central cell, respectively). Heatwaves, especially during the reproduction period, threaten male gametophyte (pollen) development, resulting in severe yield losses. Using maize (Zea mays) as a crop and grass model system, we found strong seed set reduction when moderate heat stress was applied for 2 d during the uni- and bicellular stages of pollen development. We show that heat stress accelerates pollen development and impairs pollen germination capabilities when applied at the unicellular stage. Heat stress at the bicellular stage impairs sperm cell development and transport into pollen tubes. To understand the course of the latter defects, we used marker lines and analyzed the transcriptomes of isolated sperm cells. Heat stress affected the expression of genes associated with transcription, RNA processing and translation, DNA replication, and the cell cycle. This included the genes encoding centromeric histone 3 (CENH3) and α-tubulin. Most genes that were misregulated encode proteins involved in the transition from metaphase to anaphase during pollen mitosis II. Heat stress also activated spindle assembly check point and meta- to anaphase transition genes in sperm cells. In summary, misregulation of the identified genes during heat stress at the bicellular stage results in sperm cell development and transport defects ultimately leading to sterility.
对于开花植物（被子植物）的成功双受精，花粉管将 2 个非运动精子细胞输送到雌性配子（卵子和中央细胞）。热浪，特别是在繁殖期，威胁到雄性配子体（花粉）的发育，导致严重的产量损失。我们使用玉米（Zea mays）作为作物和草模式系统，发现当在花粉发育的单细胞和二细胞阶段适度热应激持续 2 天时，结实率显著降低。我们表明，当在单细胞阶段施加热应激时，它会加速花粉发育并损害花粉萌发能力。在二细胞阶段施加热应激会损害精子细胞的发育和向花粉管中的运输。为了了解后者缺陷的过程，我们使用标记线并分析了分离的精子细胞的转录组。热应激影响与转录、RNA 加工和翻译、DNA 复制和细胞周期相关的基因的表达。这包括着丝粒组蛋白 3（CENH3）和α-微管蛋白的编码基因。大多数失调的基因编码参与花粉有丝分裂 II 中期到后期过渡的蛋白质。热应激还在精子细胞中激活了纺锤体组装检查点和中期到后期过渡基因。总之，在二细胞阶段的热应激期间，鉴定出的基因的失调导致精子细胞发育和运输缺陷，最终导致不育。
