Misra Chandra Shekhar, Sousa António G G, Khan Hasna, Pasha Asher, Provart Nicholas J, Borg Michael, Becker Jörg D
Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Av. da República, Oeiras, 2780-157, Portugal.
Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal.
Plant J. 2025 Mar;121(6):e70095. doi: 10.1111/tpj.70095.
When pollen lands on a receptive stigma, it germinates and extends a tube inside the transmitting tissue of the pistil to deliver the sperm cells for double fertilization. The growth of the pollen tube triggers significant alterations in its gene expression. The extent to which these changes occur in the vegetative cell or extend to the sperm cells transported by the tube is unclear but important to determine since sperm cells are believed to acquire a competency for fertilization during pollen-pistil interactions. To address these questions, we compared the transcriptomes of Arabidopsis thaliana sperm cells and vegetative nuclei isolated from mature pollen grains with those isolated from in vitro-grown pollen tubes. Importantly, we also compared transcriptomes of sperm cells obtained from pollen tubes grown under semi-in vivo conditions where tubes passed through a pistil section. Our data show that extensive transcriptomic changes occur in sperm cells during pollen tube growth, some of which are elicited only as sperms are carried through the pistil. Their analysis reveals a host of previously unidentified transcripts that may facilitate sperm maturation and gamete fusion. The vegetative cell undergoes even more extensive transcriptomic reprogramming during pollen tube growth, mainly through the upregulation of genes associated with pollen tube growth and vesicle-mediated transport. Interestingly, ATAC-seq data show that the promoters of genes upregulated in sperm during pollen tube growth are already accessible in sperm chromatin of mature pollen grains, suggesting pre-configured promoter accessibility. This study's expression data can be further explored here: https://bar.utoronto.ca/eFP-Seq_Browser/.
当花粉落在可受精的柱头上时，它会萌发并在雌蕊的传递组织内延伸出一根花粉管，以输送精子细胞进行双受精。花粉管的生长会引发其基因表达的显著变化。这些变化在营养细胞中发生的程度，或者是否延伸到由花粉管运输的精子细胞，目前尚不清楚，但由于人们认为精子细胞在花粉 - 雌蕊相互作用过程中获得受精能力，所以确定这一点很重要。为了解决这些问题，我们将从成熟花粉粒中分离出的拟南芥精子细胞和营养核的转录组与从体外生长的花粉管中分离出的转录组进行了比较。重要的是，我们还比较了在半体内条件下生长的花粉管（花粉管穿过雌蕊切片）中获得的精子细胞的转录组。我们的数据表明，在花粉管生长过程中，精子细胞会发生广泛的转录组变化，其中一些变化只有在精子通过雌蕊时才会引发。对这些数据的分析揭示了许多以前未被识别的转录本，这些转录本可能有助于精子成熟和配子融合。在花粉管生长过程中，营养细胞经历了更广泛的转录组重编程，主要是通过上调与花粉管生长和囊泡介导运输相关的基因。有趣的是，ATAC-seq数据表明，在花粉管生长过程中精子中上调的基因的启动子在成熟花粉粒的精子染色质中已经可及，这表明启动子可及性是预先配置好的。本研究的表达数据可在此处进一步探索：https://bar.utoronto.ca/eFP-Seq_Browser/ 。
