Ba Liang-jie, Kuang Jian-fei, Chen Jian-ye, Lu Wang-jin
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Key Laboratory for Postharvest Science, College of Horticultural Science, South China Agricultural University , Guangzhou, Guangdong 510642, People's Republic of China.
J Agric Food Chem. 2016 Feb 3;64(4):738-45. doi: 10.1021/acs.jafc.5b05005. Epub 2016 Jan 25.
Previous studies indicated that methyl jasmonate (MeJA) treatment could effectively reduce the chilling injury of many fruits, including banana, but the underlying mechanism is poorly understood. In this study, one lateral organ boundaries (LOB) domain (LBD) gene, designated as MaLBD5, was isolated and characterized from banana fruit. Expression analysis revealed that accumulation of MaLBD5 was induced by cold temperature and MeJA treatment. Subcellular localization and transactivation assays showed that MaLBD5 was localized to the nucleus and possessed transcriptional activation activity. Protein-protein interaction analysis demonstrated that MaLBD5 physically interacted with MaJAZ1, a potential repressor of jasmonate signaling. Furthermore, transient expression assays indicated that MaLBD5 transactivated a jasmonate biosynthesis gene, termed MaAOC2, which was also induced by cold and MeJA. More interestingly, MaJAZ1 attenuated the MaLBD5-mediated transactivation of MaAOC2. These results suggest that MaLBD5 and MaJAZ1 might act antagonistically in relation to MeJA-induced cold tolerance of banana fruit, at least partially via affecting jasmonate biosynthesis. Collectively, our findings expand the knowledge of the transcriptional regulatory network of MeJA-mediated cold tolerance of banana fruit.
先前的研究表明，茉莉酸甲酯（MeJA）处理能够有效减轻包括香蕉在内的多种果实的冷害，但其中潜在的机制仍知之甚少。在本研究中，从香蕉果实中分离并鉴定了一个侧生器官边界（LOB）结构域（LBD）基因，命名为MaLBD5。表达分析显示，MaLBD5的积累受低温和MeJA处理诱导。亚细胞定位和反式激活分析表明，MaLBD5定位于细胞核且具有转录激活活性。蛋白质-蛋白质相互作用分析证明，MaLBD5与茉莉酸信号的潜在抑制因子MaJAZ1发生物理相互作用。此外，瞬时表达分析表明，MaLBD5反式激活了一个名为MaAOC2的茉莉酸生物合成基因，该基因也受低温和MeJA诱导。更有趣的是，MaJAZ1减弱了MaLBD5介导的MaAOC2的反式激活。这些结果表明，MaLBD5和MaJAZ1可能在MeJA诱导的香蕉果实耐冷性方面发挥拮抗作用，至少部分是通过影响茉莉酸生物合成来实现的。总体而言，我们的研究结果扩展了对MeJA介导的香蕉果实耐冷性转录调控网络的认识。
