title: Activator- and repressor-type MYB transcription factors are involved in chilling injury induced flesh lignification in loquat via their interactions with the phenylpropanoid pathway.
abstract: Lignin biosynthesis and its transcriptional regulatory networks have been studied in model plants and woody trees. However, lignification also occurs in some fleshy fruit and has rarely been considered in this way. Loquat ( Eriobotrya japonica ) is one such convenient tissue for exploring the transcription factors involved in regulating fruit flesh lignification. Firmness and lignin content of 'Luoyangqing' loquat were fund to increase during low-temperature storage as a typical symptom of chilling injury, while heat treatment (HT) and low-temperature conditioning (LTC) effectively alleviated them. Two novel EjMYB genes, EjMYB1 and EjMYB2, were isolated and were found to be localized in the nucleus. These genes responded differently to low temperature, with EjMYB1 induced and EjMYB2 inhibited at 0 °C. They also showed different temperature responses under HT and LTC conditions, and may be responsible for different regulation of flesh lignification at the transcriptional level. Transactivation assays indicated that EjMYB1 and EjMYB2 are a transcriptional activator and repressor, respectively. EjMYB1 activated promoters of both Arabidopsis and loquat lignin biosynthesis genes, while EjMYB2 countered the inductive effects of EjMYB1. This finding was also supported by transient overexpression in tobacco. Regulation of lignification by EjMYB1 and EjMYB2 is likely to be achieved via their competitive interaction with AC elements in the promoter region of lignin biosynthesis genes such as Ej4CL1.
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China.
authors.forename: Xue-ren
authors.initials: XR
authors.lastname: Yin
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China.
authors.forename: Jiao-ke
authors.initials: JK
authors.lastname: Zeng
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China.
authors.forename: Hang
authors.initials: H
authors.lastname: Ge
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China.
authors.forename: Min
authors.initials: M
authors.lastname: Song
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China.
authors.forename: Chang-Jie
authors.initials: CJ
authors.lastname: Xu
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China.
authors.forename: Xian
authors.initials: X
authors.lastname: Li
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland, New Zealand.
authors.forename: Ian B
authors.initials: IB
authors.lastname: Ferguson
authors.affiliation: Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China akun@zju.edu.cn.
authors.forename: Kun-song
authors.initials: KS
authors.lastname: Chen
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D003080:Cold Temperature; D031983:Eriobotrya / Q000235:genetics / Q000378:metabolism*; D005638:Fruit / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008031:Lignin / Q000096:biosynthesis*; D011401:Promoter Regions, Genetic; D020005:Propanols / Q000378:metabolism; D014026:Nicotiana; D014157:Transcription Factors / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D020005:Propanols; D014157:Transcription Factors; C439395:1-phenylpropanol; D008031:Lignin
keywords: Chilling injury; Loquat; MYB; flesh lignification; heat treatment; low-temperature condition; transcriptional regulation.