The expression of genes encoding components of ABA and metabolic signalling pathways in developing barley endosperm and embryo was investigated. The genes included HvRCAR35_47387 and HvRCAR35_2538 (encoding ABA receptors), HvABI1d (protein phosphatase 2C), HvSnRK2.4, HvSnRK2.6 and HvPKABA1 (SnRK2-type protein kinases) and HvABI5 (ABA response element binding protein; AREBP), as well as two genes encoding SnRK1-type protein kinases. Both SnRK1 and SnRK2 phosphorylate AREBPs, but SnRK2 is activated by ABA whereas SnRK1 may be broken down. Multiple cereal AREBPs with two conserved SnRK1/2 target sites and another class of BZIP transcription factors with SnRK1/2 binding sites, including HvBLZ1, were identified. Barley grain (cv. Triumph) was sampled at 15, 20, 25 and 30 days post-anthesis (dpa). HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 were expressed highly in the endosperm but at much lower levels in the embryo. Conversely, HvPKABA1 and HvRCAR35_2538 were expressed at higher levels in the embryo than the endosperm, while HvSnRK2.6 was expressed at similar levels in both. HvRCAR35_47387, HvABI1d, HvSnRK2.4 and HvABI5 all peaked in expression in the endosperm at 20 dpa. A model is proposed in which ABA brings about a transition from a SnRK1-dominated state in the endosperm during grain filling to a SnRK2-dominated state during maturation.

中文翻译：

---

脱落酸（ABA）及代谢信号因子在大麦胚乳和胚发育中的表达分析

研究了大麦胚乳和胚发育过程中编码ABA成分和代谢信号通路的基因的表达。这些基因包括 HvRCAR35_47387 和 HvRCAR35_2538（编码 ABA 受体）、HvABI1d（蛋白磷酸酶 2C）、HvSnRK2.4、HvSnRK2.6 和 HvPKABA1（SnRK2 型蛋白激酶）和 HvABI5（ABA 反应元件结合蛋白；AREBP），以及两个编码 SnRK1 型蛋白激酶的基因。SnRK1 和 SnRK2 都磷酸化 AREBP，但 SnRK2 被 ABA 激活，而 SnRK1 可能被分解。鉴定了具有两个保守的 SnRK1/2 靶位点和另一类具有 SnRK1/2 结合位点的 BZIP 转录因子（包括 HvBLZ1）的多种谷物 AREBP。在开花后 15、20、25 和 30 天 (dpa) 对大麦谷物 (cv. Triumph) 进行取样。HvRCAR35_47387、HvABI1d、HvSnRK2。4和HvABI5在胚乳中高表达，但在胚胎中的表达水平要低得多。相反，HvPKABA1 和 HvRCAR35_2538 在胚胎中的表达水平高于胚乳，而 HvSnRK2.6 在两者中的表达水平相似。HvRCAR35_47387、HvABI1d、HvSnRK2.4 和 HvABI5 均在 20 dpa 时在胚乳中的表达达到峰值。提出了一个模型，其中 ABA 在灌浆期间使胚乳中的 SnRK1 主导状态转变为成熟期间的 SnRK2 主导状态。