Regulation of loquat fruit low temperature response and lignification involves interaction of heat shock factors and genes associated with lignin biosynthesis
Regulation of loquat fruit low temperature response and lignification involves interaction of heat shock factors and genes associated with lignin biosynthesis
复制标题
枇杷果实低温反应和木质化的调节涉及热激因子和木质素生物合成相关基因的相互作用
DOI：
10.1111/pce.12741
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发表时间：
2016-08-01
影响因子：
7.3
通讯作者：
Chen, Kun-song
中科院分区：
文献类型：
--
作者：
Zeng, Jiao-ke;Li, Xian;Chen, Kun-song
木质素代谢的转录调控机制已在模式植物和木本树木以及果实如枇杷（Eriobotrya japonica）中被广泛研究。与已知的NAC、MYB和AP 2/ERF转录因子不同，热激因子（HSFs）在木质素调控中的作用鲜有报道。采用热处理（HT）和低温调质（LTC）两种处理方法缓解低温诱导的枇杷果实木质化。基因表达分析表明，EjHSF 1转录丰度，在平行的热休克蛋白基因（EjHsp），诱导HT，而表达的EjHSF 3抑制LTC。利用双荧光素酶分析，EjHSF 1和EjHSF 3分别反式激活EjHsp基因和木质素生物合成相关基因的启动子。因此，EjHSF转录因子在冷害诱导的果实木质化过程中有两种不同的调控机制：EjHSF 1转录调控的EjHsp基因参与耐冷性，而EjHSF 3转录调控的木质素生物合成。此外，还研究了EjHSF 3与先前表征的果实木质化调节因子EjAP 2 -1、EjMYB 1和EjMYB 2之间的关系。酵母双杂交（Y2 H）和生物分子荧光互补（BiFC）测定证明了EjHSF 3和EjAP 2 -1之间的蛋白质-蛋白质相互作用。因此，EjHSF 3参与果实木质化是通过木质素生物合成基因和调节因子EjAP 2 -1。
Transcriptional regulatory mechanisms underlying lignin metabolism have been widely studied in model plants and woody trees, as well as fruit, such as loquat (Eriobotrya japonica). Unlike the well-known NAC, MYB and AP2/ERF transcription factors, the roles of heat shock factors (HSFs) in lignin regulation have been rarely reported. Two treatments (heat treatment, HT; low temperature conditioning, LTC) were applied to alleviate low temperature-induced lignification in loquat fruit. Gene expression analysis indicated that EjHSF1 transcript abundance, in parallel with heat shock protein genes (EjHsp), was induced by HT, while expression of EjHSF3 was repressed by LTC. Using dual-luciferase assays, EjHSF1 and EjHSF3 trans-activated the promoters of EjHsp genes and lignin biosynthesis-related genes, respectively. Thus, two distinct regulatory mechanisms of EjHSF transcription factors in chilling injury-induced fruit lignification are proposed: EjHSF1 transcriptionally regulated EjHsp genes are involved in chilling tolerance, while EjHSF3 transcriptionally regulated lignin biosynthesis. Furthermore, the relations between EjHSF3 and previously characterized fruit lignification regulators, including EjAP2-1, EjMYB1 and EjMYB2, were also investigated. Yeast-two hybrid (Y2H) and biomolecular fluorescence complementation (BiFC) assays demonstrated protein-protein interaction between EjHSF3 and EjAP2-1. Thus, the involvement of EjHSF3 in fruit lignification is via both lignin biosynthetic genes and the regulator, EjAP2-1.