Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China.
The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China.
J Exp Bot. 2017 Nov 2;68(18):5129-5136. doi: 10.1093/jxb/erx330.
Lignin is an important component of many plant secondary cell walls. In the fruit of loquat (Eriobotrya japonica), lignification of cell walls in the fleshy tissue occurs when fruit are subjected to low-temperature storage, which is commonly used to avoid the rapid senescence that occurs at room temperature. In this study, two NAC domain genes, EjNAC3 and EjNAC4, were isolated and shown to be significantly induced at 0 °C, which was concomitant with an increase in the fruit lignification index. Lignification and expression of both EjNAC3 and EjNAC4 were inhibited by low-temperature conditioning and by heat treatment. In addition, EjNAC3 trans-activated the lignin biosynthesis-related EjCAD-like promoter, which was measured using a dual-luciferase assay. Further analysis with yeast one-hybrid and electrophoretic mobility shift assays indicated that EjNAC3 could physically bind to the promoter of the EjCAD-like gene. Thus, EjNAC3 is a direct regulator of loquat chilling-induced lignification, via regulations of EjCAD-like.
木质素是许多植物次生细胞壁的重要组成部分。在枇杷（Eriobotrya japonica）果实中，果肉细胞壁的木质化发生在果实进行低温贮藏时，这通常用于避免在室温下发生的快速衰老。在这项研究中，分离出两个 NAC 结构域基因 EjNAC3 和 EjNAC4，它们在 0°C 时显著诱导表达，同时果实木质素指数增加。EjNAC3 和 EjNAC4 的木质化和表达均受到低温调节和热处理的抑制。此外，EjNAC3 可反式激活木质素生物合成相关的 EjCAD 样启动子，这通过双荧光素酶测定进行测量。酵母单杂交和电泳迁移率变动分析的进一步分析表明，EjNAC3 可以与 EjCAD 样基因的启动子物理结合。因此，EjNAC3 通过调节 EjCAD 样基因，是枇杷冷藏诱导木质化的直接调控因子。
