Abscisic acid (ABA) is a major regulator of non-climacteric fruit ripening; however, the role of ABA in the ripening of climacteric fruit is not clear. Here, as a typical climacteric fruit, apricots were used to investigate the role of ABA in fruit ripening. Based on weighted gene co-expression network analysis (WGCNA) of our previous transcriptome data, we treated ‘Danxing’ fruit with exogenous ABA and obtained ABA receptor genes, genes related to ABA biosynthesis and signal transduction, and analyzed the response of these candidate genes to exogenous ABA during fruit ripening. Subsequently, the full length of candidate PYLs genes were cloned, and their putative function were analyzed by phylogenetic analysis and protein structure domain analysis. And then the function of one candidate gene PaPYL9 was verified by using transgenic tomato. Furthermore, the response genes in transgenic tomato were screened by transcriptome sequencing, and ultimately the related regulatory network was proposed. The results showed that the injection of exogenous 1.89 mmol·L^-1 ABA remarkably promoted fruit coloration, and increased the color index for red grapes (CIRG) and the total soluble solids (TSS) content, but significantly decreased the firmness and titratable acid (TA) content (p < 0.01). Nordihydroguaiaretic acid (NDGA), the inhibitor of ABA, appeared to have the converse role in TA, TSS, CIRG and firmness, during the ripening process. One NCED (9-cis-epoxycarotenoiddioxygenase) and five ABA receptor genes related to signal transduction were mined from the transcriptome data of apricot fruit through WGCNA. Compared with the control, the expression levels of NCED1, PYL9 (PYR/PYL/RCAR), SnRK2 (SUCROSE NON-FERMENTING1 (SNF1)-RELATED PROTEIN KINASE 2S), and ABF2 (ABRE-binding bZIP transcription) were induced dramatically by ABA treatment (p < 0.01), while NDGA treatment significantly inhibited their expression. Based on gene expression and protein domain analysis, we inferred that PaPYL9 is putatively involved in apricot fruit ripening. Overexpression of PaPYL9 in Micro-TOM tomatoes resulted in the promotion of early ripening. Simultaneously, the expression levels of genes related ethylene biosynthesis, chlorophyll degradation, fruit softening, flavor formation, pigment synthesis, and metabolism were all significantly induced in overexpression of PaPYL9 tomatoes. This indicates the central role of ABA in climacteric fruit ripening. A regulatory network was tentatively proposed, laying the foundation to unveil the molecular mechanism of the regulatory role of PaPYL9 in fruit ripening.

脱落酸 (ABA) 是非跃变果实成熟的主要调节剂；然而，ABA在更年期果实成熟中的作用尚不清楚。在这里，作为典型的更年期水果，杏被用来研究 ABA 在果实成熟中的作用。基于我们之前的转录组数据的加权基因共表达网络分析（WGCNA），我们用外源ABA处理'丹兴'果实，获得了ABA受体基因，与ABA生物合成和信号转导相关的基因，并分析了这些候选基因的反应。果实成熟期外源ABA。随后，克隆了全长的候选PYLs基因，并通过系统发育分析和蛋白质结构域分析对其推定的功能进行了分析。然后利用转基因番茄验证了一个候选基因PaPYL9的功能。此外，通过转录组测序筛选转基因番茄中的反应基因，最终提出相关调控网络。结果表明，注射外源性1.89 mmol·L^-1 ABA显着促进果实着色，提高红葡萄颜色指数（CIRG）和总可溶性固形物（TSS）含量，但显着降低硬度和可滴定酸（TA）含量（p  < 0.01）。去甲二氢愈创木酸 (NDGA) 是 ABA 的抑制剂，在成熟过程中似乎对 TA、TSS、CIRG 和硬度具有相反的作用。通过WGCNA从杏果实的转录组数据中挖掘出1个NCED（9-顺-环氧类胡萝卜素双加氧酶）和5个与信号转导相关的ABA受体基因。与对照相比，NCED1、PYL9（PYR/PYL/RCAR）、SnRK2（蔗糖非发酵1（SNF1）-相关蛋白激酶2S）和ABF2的表达水平(ABRE 结合 bZIP 转录) 被 ABA 处理显着诱导 ( p  < 0.01)，而 NDGA 处理显着抑制它们的表达。基于基因表达和蛋白结构域分析，我们推断PaPYL9推测参与了杏果实的成熟。PaPYL9的过表达在 Micro-TOM 番茄中，促进了早熟。同时，乙烯生物合成、叶绿素降解、果实软化、风味形成、色素合成和代谢相关基因的表达水平均显着诱导PaPYL9番茄过表达。这表明ABA在更年期果实成熟中的核心作用。初步提出了一个调控网络，为揭示PaPYL9调控果实成熟的分子机制奠定了基础。