Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, 87036 Arcavacata of Rende (Cosenza), Italy.
Botanical Garden, University of Padova, 25123 Padova, Italy.
J Exp Bot. 2024 Jun 7;75(11):3351-3367. doi: 10.1093/jxb/erae102.
In gymnosperms such as Ginkgo biloba, the arrival of pollen plays a key role in ovule development, before fertilization occurs. Accordingly, G. biloba female plants geographically isolated from male plants abort all their ovules after the pollination drop emission, which is the event that allows the ovule to capture pollen grains. To decipher the mechanism induced by pollination required to avoid ovule senescence and then abortion, we compared the transcriptomes of pollinated and unpollinated ovules at three time points after the end of the emission of pollination drop. Transcriptomic and in situ expression analyses revealed that several key genes involved in programmed cell death such as senescence and apoptosis, DNA replication, and cell cycle regulation were differentially expressed in unpollinated ovules compared to pollinated ovules. We provide evidence that the pollen captured by the pollination drop affects auxin local accumulation and might cause deregulation of key genes required for the ovule's programmed cell death, activating both the cell cycle regulation and DNA replication genes.
在裸子植物如银杏中，花粉的到来在受精发生之前对胚珠发育起着关键作用。因此，与雄性植物在地理上隔离的雌性银杏植物在花粉排放后会使所有胚珠流产，花粉排放是允许胚珠捕获花粉粒的事件。为了解释避免胚珠衰老和随后流产所诱导的授粉机制，我们比较了授粉和未授粉胚珠在授粉滴排放结束后三个时间点的转录组。转录组和原位表达分析表明，与授粉胚珠相比，未授粉胚珠中几个与程序性细胞死亡相关的关键基因（如衰老和凋亡、DNA 复制和细胞周期调控）的表达存在差异。我们提供的证据表明，授粉滴中捕获的花粉影响生长素的局部积累，并可能导致胚珠程序性细胞死亡所需关键基因的失调，从而激活细胞周期调控和 DNA 复制基因。
