MIKC classic (MIKC^C)-type MADS-box genes encode transcription factors that function in various developmental processes, including angiosperm floral organ identity. Phylogenetic analyses of the MIKC^C-type MADS-box family, including genes from non-flowering plants, suggest that the increased numbers of these genes in flowering plants is related to their functional divergence; however, their precise functions in non-flowering plants and their evolution throughout land plant diversification are unknown. Here, we show that MIKC^C-type MADS-box genes in the moss Physcomitrella patens function in two ways to enable fertilization. Analyses of protein localization, deletion mutants and overexpression lines of all six genes indicate that three MIKC^C-type MADS-box genes redundantly regulate cell division and growth in the stems for appropriate external water conduction, as well as the formation of sperm with motile flagella. The former function appears to be maintained in the flowering plant lineage, while the latter was lost in accordance with the loss of sperm.

中文翻译：

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Physcomitrella MADS-box基因调节供水和精子运动以进行受精。

MIKC经典（MIKC ^C）型MADS-box基因编码在各种发育过程中起作用的转录因子，包括被子植物花器官的身份。对MIKC ^C型MADS-box家族（包括来自非开花植物的基因）进行的系统进化分析表明，开花植物中这些基因数量的增加与它们的功能差异有关。然而，它们在非开花植物中的确切功能以及在整个陆地植物多样化中的进化尚不清楚。在这里，我们显示了苔藓小立碗藓中的MIKC ^C型MADS-box基因以两种方式起作用以实现受精。对所有六个基因的蛋白质定位，缺失突变体和过度表达谱线的分析表明，三个MIKC ^C型MADS-box基因冗余地调节茎中的细胞分裂和生长，以适当地进行外部水传导，以及形成能动鞭毛的精子。前者的功能似乎在开花植物谱系中得以维持，而后者则根据精子的丧失而丧失。