2021年7月19日，国家香蕉产业技术体系品种改良岗位的论文“MaMADS36 plays a central role in regulating banana fruit ripening”被国际Top 学术期刊《Journal of Experimental Botany》(SCI, Top, IF=6.992)录用发表。本研究首次获得了MaMADS36 转基因红香蕉。MaMADS36 是香蕉果实成熟所必需的，它与74 种蛋白质相互作用形成共表达网络，是调控果实成熟的重要开关，并且MaMADS36 能够直接结合MaBAM9b 启动子的CA/T(r)G 盒来控制淀粉降解，揭示了MADS-box 转录因子调控果实成熟的分子机制。岗位专家金志强研究员和刘菊华研究员为通讯作者。该项工作得到了财政部和农业农村部-国家现代农业产业技术体系资助。

作者：刘菊华*，刘梦婷，王静毅，张静，苗红霞，王卓，贾彩红，张建斌，徐碧玉*，金志强*

题目：MaMADS36调控香蕉果实成熟的分子机制

摘要：香蕉是研究淀粉转化型和呼吸跃变型水果的模式作物。成熟和淀粉降解是其果实品质形成且相伴发生的两个重要生物过程，但一直缺少即能调控淀粉降解也能调节乙烯生物合成或成熟的重要开关。本研究通过分别遗传转化MaMADS36转录因子 (也是MuMADS1, Ma05_G18560.1）的正义载体和反义载体至红香蕉。结果表明，MaMADS36可以与74种蛋白互作形成共表达网络，并可作为调节乙烯生物合成、淀粉降解、软化和糖代谢的重要开关。在这些靶基因中，选择了β-淀粉酶9b (MaBAM9b, Ma05_T07800.1) 进一步研究MaMADA36的调控机制。MaMADS36 能够直接结合MaBAM9b 启动子的CA/T(r)G 盒，在成熟过程中其显著增加了MaBAM9b的转录，以及淀粉酶活性和淀粉降解。这些发现为我们了解TFs如何作为重要开关调控果实成熟和淀粉降解提供了新认知；同时，也为香蕉果实品质形成与精细调控，通过基因编辑技术获得优质新品系或新品种提供了重要的基因资源。

 全文链接：https://doi.org/10.1093/jxb/erab341

Juhua Liu*, Mengting Liu, Jingyi Wang, Jing Zhang, Hongxia Miao, Zhuo Wang, Caihong Jia, Jianbin Zhang, Biyu Xu*, Zhiqiang Jin*. MaMADS36 plays a central role in regulating banana fruit ripening. Journal of Experimental Botany, 2021, erab341.

Abstract

Bananas are model fruits for studying starch conversion and climactericity. Starch degradation and ripening are two important biological processes that occur concomitantly in banana fruit. Ethylene biosynthesis, and postharvest fruit ripening processes, i.e., starch degradation, fruit softening, and sugar accumulation are highly correlated and thus could be controlled by a common regulatory switch. However, this switch has not been identified. In this study, we transformed red banana with sense and anti-sense constructs of the MaMADS36 transcription factor (also MuMADS1, Ma05_g18560.1). Analysis of these lines showed that MaMADS36 interacts with 74 other proteins to form a co-expression network and could act as an important switch to regulate ethylene biosynthesis, starch degradation, softening, and sugar accumulation. Among these target genes, Musa acuminata beta-amylase 9b (MaBAM9b, Ma05_t07800.1) that encodes a starch degradation enzyme, was selected to further investigate the regulatory mechanism of MaMADS36. Our findings indicated that MaMADS36 directly binds the CA/T(r)G box of the MaBAM9b promoter to increase MaBAM9b transcription and in turn, enzyme activity, and starch degradation during ripening. These results will help to further our understanding of the fine regulatory mechanisms of MADS-box transcription factors in regulating fruit ripening, which can be applied to breeding programs to improve fruit shelf-life.

Proposed working model depicting the roles of MaMADS36 in regulating fruit ripening.