香蕉MuMADS1和MaOFP1协同调控MaBAM9b介导淀粉降解的分子机制

Banana is a typically climacteric and starch convertible fruit. Postharvest fruit ripening process is the process of fruit quality formation. Starch degradation is the foundation of quality formation. Therefore, investigating the starch breakdown is a key biological problem for postharvest banana fruit. We found that banana MuMADS1 and MaOFP1 could cooperatively regulate starch degradation and the regulated key target gene was beta-amylase MaBAM9b based on our previous study. This project will further investigate the regulatory relationship between MuMADS1 and MaOFP1 and MaBAM9b, and the effects of complex formation of MuMADS1 and MaOFP1 on the transcriptional activity of MaBAM9b and the enzyme activity by molecular biology methods. The downstream metabolites will also be analyzed. The purpose of this project is to understand the regulatory pattern of key enzyme gene coordinately regulated by MuMADS1 and MaOFP1 on fruit starch degradation metabolism and illuminate the molecular mechanism of coordinate regulation on starch degradation metabolism. These findings will help to further understanding the refined regulatory mechanism of transcription factors during starch degradation process, promote banana fruit quality improvement and support the banana industry development. These findings will also provide new idea for other tropical fruits’ quality formation and regulation and have important practical application value.

香蕉是典型的呼吸跃变型水果和淀粉转化型果实，采后成熟过程就是品质形成的过程，淀粉降解是品质形成的基础，因此研究淀粉降解是香蕉果实采后的一个关键生物学问题。我们前期研究发现香蕉两个转录因子MuMADS1和MaOFP1可以协同调控淀粉降解，所调控的关键酶基因是β-淀粉酶基因MaBAM9b。以此为基础，本项目拟采用分子生物学方法，研究MuMADS1和MaOFP1与MaBAM9b的调控关系，研究MuMADS1与MaOFP1复合体形成对MaBAM9b转录活性及酶活性的影响，并对下游代谢产物进行分析。目的是明确MuMADS1和MaOFP1协同调控香蕉果实淀粉分解代谢关键酶基因的方式，阐明协同调控淀粉分解代谢的分子机制。研究结果有助于深入了解香蕉果实淀粉降解过程中转录调控因子的精细调控机制，促进香蕉品质改良，支撑香蕉产业发展，而且为其它热带水果采后品质形成与调控提供新思路，具有重要的实际应用价值。

香蕉是典型的呼吸跃变型水果和淀粉转化型果实，采后成熟过程就是品质形成的过程，淀粉降解是品质形成的基础，因此研究淀粉降解是香蕉果实采后的一个关键生物学问题。我们前期研究发现香蕉两个转录因子MuMADS1和MaOFP1可以协同调控淀粉降解，所调控的关键酶基因是β-淀粉酶基因MaBAM9b。以此为基础，本项目采用了分子生物学方法，研究MuMADS1和MaOFP1与MaBAM9b的调控关系，研究MuMADS1与MaOFP1复合体形成机制并对MaBAM9b转录活性和淀粉降解代谢的影响，有了重大发现。明确了MaBAM9b启动子的结构与功能；发现了MuMADS1转录因子能特异性地与MaBAM9b的启动子的CA/T(r)G-box结合；发现了MuMADS1的K-domain和MaOFP1的ovate-domain的精细互作机制；证实了MuMADS1和MaOFP1形成复合体后对MaBAM9b的转录调控作用，并利用病毒介导的基因沉默技术解析了MuMADS1 和MaOFP1协同调控MaBAM9b介导淀粉降解的分子机制。研究结果有助于深入了解香蕉果实淀粉降解过程中转录调控因子的精细调控机制，促进香蕉品质改良，支撑香蕉产业发展，而且为其它热带水果采后品质形成与调控提供新思路，具有重要的实际应用价值。