IRHS-UMR1345, Université d'Angers, INRAE, Institut Agro, SFR 4207 QuaSaV, Beaucouzé, France.
Departamento de Produção Vegetal, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Botucatu, Brazil.
Plant Cell Environ. 2020 Oct;43(10):2508-2522. doi: 10.1111/pce.13853. Epub 2020 Aug 23.
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.
在种子成熟的后期阶段，种子获得了两个关键的适应性特征，这有助于种子寿命和传播、长寿和休眠。种子特异性热休克转录因子 A9 是晚期种子成熟转录网络中的一个重要枢纽基因。在这里，我们证明 HSFA9 在耐热性中起作用，而不是在体外种子保存中起作用。在适度的储存相对湿度（RH）下，Medicago truncatula 和 Arabidopsis 的 hsfa9 种子的储存寿命相当，但在高 RH 下，hsfa9 种子比野生型种子更快地失去活力。此外，我们表明，在 M. truncatula 中，Mthsfa9 种子在成熟后期获得了更多的休眠。瞬时表达 hairy roots 中的 MtHSFA9 和 Mthsfa9 Tnt1 插入突变体的转录组分析鉴定了参与 ABA 生物合成、分解代谢和信号转导的基因的失调。与这些结果一致，Mthsfa9 种子表现出较高的 ABA 水平和对 ABA 的更高敏感性。这些数据表明，在豆科植物中，HSFA9 通过调节激素平衡，作为种子发育过程中种子休眠深度的负调节剂。
