【作者】 陈建业； 贺立红； 蒋跃明； 王勇； 陆旺金；

【机构】 华南农业大学园艺学院广东省果蔬保鲜重点实验室； 仲恺农业技术学院生命科学院； 中国科学院华南植物园；

【摘要】 为进一步研究苯丙氨酸解氨酶(PAL,EC 4.3.1.5)与香蕉果实耐冷性的分子细胞学机理,本研究以巴西香蕉(Musa AAA Cavendish.cv.Brazil)为试材,采用热处理和PAL活性专一性抑制剂AIP(2-aminoindan- 2-phosphonic acid),运用Western和Northern blotting印迹分析及胶体金免疫电子显微镜定位等分子细胞学实验技术,研究了冷害过程中PAL的表达和亚细胞定位与耐冷性的关系。结果表明:热处理明显促进了PAL的活性,促进了酚类物质的合成,减轻了果实冷害,Western和Northern blotting印迹分析证实了热处理对PAL的激活作用是通过增加其蛋白表达量和mRNA量来实现的;AIP抑制剂处理后,抑制了热处理诱导的PAL的激活和酚类物质的合成,加重了果实冷害。胶体金免疫电镜定位显示,香蕉果皮维管组织细胞中的PAL主要分布于细胞壁和次生壁加厚层中,而在细胞质、叶绿体(质体)中和淀粉粒中分布较少,热处理后香蕉果皮维管组织细胞中金颗粒数量明显增多,且主要在细胞壁及次生壁中大量分布,而AIP抑制剂处理后,果皮维管组织细胞金颗粒数量一直保持较低水平.仅见少量金颗粒分布在细胞壁和次生壁。这些结果表明,PAL的激活与表达在香蕉果实的耐冷性诱导中起着重要作用。更多还原

【Abstract】 Increasing evidence suggests that phenylalanine ammonia-lyase (PAL,EC 4.3.1.5) is associated with low temperature stress in plant tissues.Banana fruit are highly susceptible to chilling injury.However,little is known about the role of PAL (i.e.,gene expression;protein level,activity and subcellular distribution) in fruit chilling.In this work,the involvement of PAL induced by heat treatment (38℃for 3 days) prior to storage (8℃) in chilling tolerance was investigated.The PAL inhibitor 2-aminoindan-2-phosphonic acid (AIP) was also used to further study the role of PAL in the chilling tolerance.The results showed that mRNA transcripts (MaPAL1 and MaPAL2) and PAL protein levels increased during storage at a chilling temperature.Heat treatment prior to storage alleviated chilling injury and enhanced PAL activity,protein amount,and MaPAL1 and MaPAL2 transcript levels.Sub-cellular distribution of PAL observed by immunogold electron-microscopy revealed that PAL was predominantly located in cell walls,secondary cell walls,cytoplasm and chloroplasts within vascular tissues.Furthermore,there was a greater PAL localization in cell walls and secondary cell walls after heat pretreatment.The increases in parameters of PAL upon heat pretreatment were all strongly inhibited by AIP treatment,which resulted in more serious symptoms of chilling injury.Thus,these findings indicated that PAL play a important role in heat pretreatment-induced chilling tolerance of banana fruit and the induction of PAL by heat pretreatment was regulated at both the transcriptional and translational levels.更多还原