During the later stages of seed maturation, two key adaptive traits are acquired that contribute to seed lifespan and dispersal, longevity and dormancy. The seed‐specific heat shock transcription factor A9 is an important hub gene in the transcriptional network of late seed maturation. Here, we demonstrate that HSFA9 plays a role in thermotolerance rather than in ex situ seed conservation. Storage of hsfa9 seeds of Medicago truncatula and Arabidopsis had comparable lifespan at moderate storage relative humidity (RH), whereas at high RH, hsfa9 seeds lost their viability much faster than wild type seeds. Furthermore, we show that in M. truncatula, Mthsfa9 seeds acquired more dormancy during late maturation than wild type. Transient expression of MtHSFA9 in hairy roots and transcriptome analysis of Mthsfa9 Tnt1 insertion mutants identified a deregulation of genes involved in ABA biosynthesis, catabolism and signalling. Consistent with these results, Mthsfa9 seeds exhibited increased ABA levels and higher sensitivity to ABA. These data suggest that in legumes, HSFA9 acts as a negative regulator of the depth of seed dormancy during seed development via the modulation of hormonal balance.

中文翻译：

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种子特有的热激因子A9通过ABA信号调节Medi藜苜蓿种子的休眠深度。

在种子成熟的后期阶段，获得了两个关键的适应性状，它们有助于种子的寿命和扩散，长寿和休眠。种子特异性热激转录因子A9是种子成熟后期转录网络中的重要中枢基因。在这里，我们证明HSFA9在耐热性中起作用，而不是在异位种子保存中起作用。ca藜和拟南芥的hsfa9种子在中等存储相对湿度（RH）下的寿命相当，而在高RH下，hsfa9种子失去活力的速度比野生型种子快得多。此外，我们在M中证明了这一点。苜蓿，MT hsfa9种子在成熟后期比野生型获得更多的休眠。Mt HSFA9在毛状根中的瞬时表达和Mt hsfa9 Tnt1插入突变体的转录组分析确定了与ABA生物合成，分解代谢和信号传导有关的基因的失调。与这些结果一致，Mthsfa9种子表现出增加的ABA水平和对ABA的更高敏感性。这些数据表明，在豆类中，HSFA9通过调节荷尔蒙平衡，在种子发育过程中充当了种子休眠深度的负调节剂。