School of Life Science and Technology, Wuhan Polytechnic University, Wuhan 430023, China.
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China.
Int J Mol Sci. 2024 Nov 14;25(22):12255. doi: 10.3390/ijms252212255.
In flowering plants, the success of fertilization depends on the rapid polar extension of a pollen tube, which delivers sperm cells to the female gametophyte for fertilization. Numerous studies have shown that the microenvironment in planta is more conducive to the growth and development of pollen tubes than that in vitro. However, how stigma factors coordinate to regulate pollen tube growth is still poorly understood. Here, we demonstrate that in tobacco, mature stigma extract, but not immature stigma extract, facilitates pollen tube growth. Comparative transcriptomic and qRT-PCR analyses showed that the differentially expressed genes during stigma maturation were mainly enriched in the metabolism pathway. Through metabolome analyses, about 500 metabolites were identified to be differently accumulated; the significantly increased metabolites in the mature stigmas mainly belonged to alkaloids, flavonoids, and terpenoids, while the downregulated differential metabolites were related to lipids, amino acids, and their derivatives. Among the different kinds of plant hormones, the cis-form contents of zeatin were significantly increased, and more importantly, cis-zeatin riboside promoted pollen tube growth in vitro. Thus, our results reveal an overall landscape of gene expression and a detailed nutritional microenvironment established for pollen tube growth during the process of stigma maturation, which provides valuable clues for optimizing in vitro pollen growth and investigating the pollen-stigma interaction.
在开花植物中，受精的成功与否取决于花粉管的快速极性延伸，花粉管将精子细胞输送到雌性配子体进行受精。大量研究表明，与体外相比，植物体内的微环境更有利于花粉管的生长和发育。然而，柱头因子如何协调以调节花粉管的生长仍知之甚少。在这里，我们证明在烟草中，成熟柱头提取物而不是未成熟柱头提取物促进花粉管的生长。比较转录组和 qRT-PCR 分析表明，柱头成熟过程中差异表达的基因主要富集在代谢途径中。通过代谢组学分析，鉴定出约 500 种不同积累的代谢物；成熟柱头中明显增加的代谢物主要属于生物碱、类黄酮和萜类化合物，而下调的差异代谢物与脂质、氨基酸及其衍生物有关。在不同种类的植物激素中，玉米素的顺式形式含量显著增加，更重要的是，顺式玉米素核苷在体外促进花粉管的生长。因此，我们的研究结果揭示了柱头成熟过程中花粉管生长所建立的基因表达整体图谱和详细的营养微环境，为优化体外花粉生长和研究花粉-柱头相互作用提供了有价值的线索。
