The kinase-associated protein phosphatase, KAPP, is negatively involved in abscisic acid (ABA) signaling. KAPP interacts physically with SnRK2.2, SnRK2.3 and SnRK2.6, and functionally acts upstream of SnRK2.2 and SnRK2.3. The kinase-associated protein phosphatase (KAPP) has been reported to be involved in the regulation of many developmental and signaling events, but it remains unknown whether KAPP is involved in ABA signaling. Here, we report that KAPP is negatively involved in ABA-mediated seed germination and early seedling growth in Arabidopsis thaliana. The two loss-of-function mutants of KAPP, kapp-1 and kapp-2, exhibit increased ABA sensitivity in ABA-induced seed germination inhibition and post-germination growth arrest. The three closely-related protein kinase, (SNF1)-related protein kinase SnRK2.2, SnRK2.3 and SnRK2.6, which play critical roles in ABA signaling, interact and co-localize with KAPP. Genetic evidence showed that the ABA-hypersensitive phenotypes caused by KAPP mutation were suppressed by the double mutation of SnRK2.2 and SnRK2.3, indicating that KAPP functions upstream of SnRK2.2 and SnRK2.3 in ABA signaling. RNA-sequencing analysis revealed that KAPP mutation affects expression of multiple ABA-responsive genes. These results demonstrated that KAPP is negatively involved in plant response to ABA, which help to understand the complicated ABA signaling mechanism.

中文翻译：

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拟南芥激酶相关蛋白磷酸酶 KAPP，与蛋白激酶 SnRK2.2/2.3/2.6 相互作用，负调节脱落酸信号。

激酶相关蛋白磷酸酶 KAPP 与脱落酸 (ABA) 信号传导负相关。KAPP 与 SnRK2.2、SnRK2.3 和 SnRK2.6 物理相互作用，并在 SnRK2.2 和 SnRK2.3 上游起作用。据报道，激酶相关蛋白磷酸酶 (KAPP) 参与了许多发育和信号传导事件的调节，但尚不清楚 KAPP 是否参与 ABA 信号传导。在这里，我们报告 KAPP 与 ABA 介导的种子萌发和拟南芥早期幼苗生长负相关。KAPP 的两个功能缺失突变体 kapp-1 和 kapp-2 在 ABA 诱导的种子萌发抑制和萌发后生长停滞中表现出更高的 ABA 敏感性。三种密切相关的蛋白激酶，（SNF1）相关蛋白激酶 SnRK2.2、SnRK2.3 和 SnRK2.6，它们在 ABA 信号传导中起关键作用，与 KAPP 相互作用和共定位。遗传证据表明KAPP突变引起的ABA超敏表型被SnRK2.2和SnRK2.3的双突变抑制，表明KAPP在ABA信号传导中位于SnRK2.2和SnRK2.3的上游。RNA 测序分析表明，KAPP 突变影响多个 ABA 反应基因的表达。这些结果表明，KAPP 与植物对 ABA 的反应负相关，这有助于理解复杂的 ABA 信号传导机制。RNA 测序分析表明，KAPP 突变影响多个 ABA 反应基因的表达。这些结果表明，KAPP 与植物对 ABA 的反应负相关，这有助于理解复杂的 ABA 信号传导机制。RNA 测序分析表明，KAPP 突变影响多个 ABA 反应基因的表达。这些结果表明，KAPP 与植物对 ABA 的反应负相关，这有助于理解复杂的 ABA 信号传导机制。