Papaya CpERF9 acts as a transcriptional repressor of cell-wall-modifying genes CpPME1/2 and CpPG5 involved in fruit ripening
Papaya CpERF9 acts as a transcriptional repressor of cell-wall-modifying genes CpPME1/2 and CpPG5 involved in fruit ripening
复制标题
DOI：
10.1007/s00299-016-2038-3
复制
发表时间：
2016-11-01
影响因子：
6.2
通讯作者：
Kuang, Jian-Fei
中科院分区：
文献类型：
--
作者：
Fu, Chang-Chun;Han, Yan-Chao;Kuang, Jian-Fei
CpERF9 通过直接结合细胞壁修饰基因 CpPME1/2 和 CpPG5 的启动子进行转录抑制，从而控制番木瓜果实成熟。番木瓜果实成熟是一个复杂且高度协调的发育过程，受乙烯的作用和众多乙烯响应基因的表达控制。乙烯反应因子（ERF）代表乙烯信号通路的最后调节因子，决定了乙烯反应的特异性。然而，关于 ERF 介导的木瓜果实成熟的转录控制机制的知识是有限的。在目前的工作中，从木瓜果实中鉴定出一种编码 AP2/ERF 蛋白的基因，该蛋白具有两个 ERF 相关的两亲性抑制 (EAR) 基序，称为 CpERF9。 CpERF9被发现定位于细胞核，并具有转录抑制能力。在木瓜果实成熟过程中，CpERF9 的表达量稳步下降，而编码果胶甲酯酶 (PME) 和多聚半乳糖醛酸酶 (PG) 的基因，如 CpPME1/2 和 CpPG5，则逐渐增加，与果实硬度的下降相平行。电泳迁移率变动分析 (EMSA) 证明 CpERF9 通过 GCC-box 基序与 CpPME1/2 和 CpPG5 启动子特异性结合。 CpERF9 在烟草中的瞬时表达抑制了 CpPME1/2 和 CpPG5 启动子活性，这取决于 CpERF9 蛋白的两个 EAR 基序。总而言之，这些研究结果表明，木瓜 CpERF9 可能通过直接结合到其启动子上，充当几个细胞壁修饰基因（例如 CpPME1/2 和 CpPG5）的转录抑制因子。
CpERF9 controls papaya fruit ripening through transcriptional repression of cell-wall-modifying genes CpPME1/2 and CpPG5 by directly binding to their promoters.Papaya fruit ripening is an intricate and highly coordinated developmental process which is controlled by the action of ethylene and expression of numerous ethylene-responsive genes. Ethylene response factors (ERFs) representing the last regulators of ethylene-signaling pathway determine the specificities of ethylene response. However, knowledge concerning the transcriptional controlling mechanism of ERF-mediated papaya fruit ripening is limited. In the present work, a gene-encoding AP2/ERF protein with two ERF-associated amphiphilic repression (EAR) motifs, named CpERF9, was characterized from papaya fruit. CpERF9 was found to localize in nucleus, and possess transcriptional repression ability. CpERF9 expression steadily decreased during papaya fruit ripening, while several genes encoding pectin methylesterases (PMEs) and polygalacturonases (PGs), such as CpPME1/2 and CpPG5, were gradually increased, paralleling the decline of fruit firmness. Electrophoretic mobility shift assay (EMSA) demonstrated a specific binding of CpERF9 to promoters of CpPME1/2 and CpPG5, via the GCC-box motif. Transient expression of CpERF9 in tobacco repressed CpPME1/2 and CpPG5 promoter activities, which was depended on two EAR motifs of CpERF9 protein. Taken together, these findings suggest that papaya CpERF9 may act as a transcriptional repressor of several cell-wall modifying genes, such as CpPME1/2 and CpPG5, via directly binding to their promoters.