Ovule development is critical to plant reproduction and free nuclear mitosis of megagametophyte (FNMM) is vital for ovule development. However, most results of ovule development were based on the studies in angiosperms, and its molecular regulation remained largely unknown in gymnosperms, particularly, during FNMM. In this context, we studied the genome-wide difference between sterile line (SL) and fertile line (FL) ovules using transcriptomics and proteomics approaches in Pinus tabuliformis Carr. Comparative analyses revealed that genes involved in DNA replication, DNA damage repair, Cell cycle, Apoptosis and Energy metabolism were highlighted. Further results showed the low expressions of MCM 2-7, RRM1, etc. perhaps led to abnormal DNA replication and damage repair, and the significantly different expressions of PARP2, CCs1, CCs3, etc. implied that the accumulated DNA double-stranded breaks were failed to be repaired and the cell cycle was arrested at G2/M in SL ovules, potentially resulting in the occurrence of apoptosis. Moreover, the deficiency of ETF-QO might hinder FNMM. Consequently, FNMM stopped and ovule aborted in SL ovules. Our results suggested a selective regulatory mechanism led to FNMM half-stop and ovule abortion in P. tabuliformis and these insights could be exploited to investigate the molecular regulations of ovule development in woody gymnosperms.

中文翻译：

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综合转录组学和蛋白质组学分析构建油松雌性不育系胚珠流产的新分子模型

胚珠发育对植物繁殖至关重要，巨型配子体 (FNMM) 的游离核有丝分裂对胚珠发育至关重要。然而，胚珠发育的大多数结果是基于对被子植物的研究，其分子调控在裸子植物中仍然很大程度上未知，特别是在 FNMM 期间。在这种情况下，我们使用油松中的转录组学和蛋白质组学方法研究了不育系 (SL) 和可育系 (FL) 胚珠之间的全基因组差异。比较分析显示，参与 DNA 复制、DNA 损伤修复、细胞周期、细胞凋亡和能量代谢的基因被突出显示。进一步的结果表明，MCM 2-7、RRM1等的低表达可能导致DNA复制和损伤修复异常，而PARP2、CCs1、CCs3等的表达差异显着。暗示积累的DNA双链断裂未能修复，细胞周期在SL胚珠的G2 / M停滞，可能导致细胞凋亡的发生。此外，ETF-QO 的不足可能会阻碍 FNMM。因此，FNMM 停止，SL 胚珠中的胚珠中止。我们的研究结果表明，选择性调控机制导致 P. tabuliformis 的 FNMM 半停和胚珠流产，这些见解可用于研究木质裸子植物胚珠发育的分子调控。