The molecular mechanisms underlying seed dormancy and germination are not fully understood. Here, we show that Arabidopsis thaliana SEED DORMANCY 4-LIKE (AtSdr4L) is a novel specific regulator of dormancy and germination. AtSdr4L encodes a protein with an unknown biochemical function that is localized in the nucleus and is expressed specifically in seeds. Loss of function of AtSdr4L results in increased seed dormancy. The germination of freshly harvested seeds of the Atsdr4l mutant is insensitive to gibberellin (GA). After-ripened mutant seeds are hypersensitive to the GA biosynthesis-inhibitor paclobutrazol but show unaltered sensitivity to abscisic acid. Several GA biosynthesis genes and GA-regulated cell wall remodeling genes are down-regulated in the mutant in both dormant and after-ripened seeds. These results suggest that the Atsdr4l mutation causes both decreased GA biosynthesis and reduced responses. In addition, a genetic analysis indicated that AtSdr4L is epistatic to DELAY OF GERMINATION1 (DOG1) for dormancy and acts upstream of RGA-LIKE 2 (RGL2) in the GA pathway. We propose that AtSdr4L regulates seed dormancy and germination by mediating both the DOG1 and GA pathways.

中文翻译：

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拟南芥SEED DORMANCY 4-LIKE通过介导赤霉素途径调节休眠和萌发。

种子休眠和萌发的分子机制尚未完全了解。在这里，我们表明拟南芥SEED DORMANCY 4-LIKE（AtSdr4L）是休眠和萌发的新型特定调节剂。AtSdr4L编码一种具有未知生化功能的蛋白质，该蛋白质位于细胞核中，并在种子中特异性表达。AtSdr4L的功能丧失导致种子休眠增加。Atsdr4l突变体的新鲜收获种子的萌发对赤霉素（GA）不敏感。熟后的突变种子对GA生物合成抑制剂多效唑具有高度的敏感性，但对脱落酸的敏感性却保持不变。在休眠和后熟种子中的突变体中，一些GA生物合成基因和GA调控的细胞壁重塑基因均被下调。这些结果表明，Atsdr41突变引起GA生物合成减少和响应降低。此外，遗传分析表明，AtSdr4L相对于DELAY OF GERMINATION1（DOG1）处于休眠状态，并在GA途径中作用于RGA-LIKE 2（RGL2）的上游。我们建议AtSdr4L通过介导DOG1和GA途径来调节种子的休眠和萌发。