Banana is a good source of carotenoids, which are bioactive metabolites with health beneficial properties for human. However, the molecular mechanism of carotenoid accumulation in banana fruit is largely unclear. In this study, we found that high temperature elevated carotenoid production in banana pulp, which is presumably due to upregulation of a subset of carotenogenic genes as well as a carotenoid biosynthesis regulator MaSPL16. Moreover, an ethylene signaling component MaEIL9 was identified, whose transcript and protein contents were also induced by high temperature. In addition, MaEIL9 positively regulates transcription of MaDXR1, MaPDS1, MaZDS1 and MaSPL16 through directly targeting their promoters. Overexpression of MaEIL9 in tomato fruit substantially increased the expression of carotenoid formation genes and elevated carotenoid content. Importantly, transiently silencing MaEIL9 in banana fruit weakened carotenoid production caused by high temperature. Taken together, these results indicate that high temperature induces carotenoid production in banana fruit, at least in part, through MaEIL9-mediated activation of MaDXR1, MaPDS1, MaZDS1 and MaSPL16 expression.

香蕉是类胡萝卜素的良好来源，类胡萝卜素是具有生物活性的代谢产物，对人体健康有益。然而，香蕉果实中类胡萝卜素积累的分子机制在很大程度上还不清楚。在这项研究中，我们发现高温提高了香蕉果肉中类胡萝卜素的产量，这可能是由于一部分类胡萝卜素基因以及类胡萝卜素生物合成调节因子MaSPL16的上调。此外，还鉴定了乙烯信号转导成分 MaEIL9，其转录物和蛋白质含量也受高温诱导。此外，MaEIL9 正调控MaDXR1、MaPDS1、MaZDS1和MaSPL16的转录通过直接针对他们的发起人。MaEIL9在番茄果实中的过表达显着增加了类胡萝卜素形成基因的表达并提高了类胡萝卜素含量。重要的是，暂时沉默香蕉果实中的MaEIL9会削弱高温引起的类胡萝卜素产生。总之，这些结果表明高温至少部分地通过 MaEIL9 介导的MaDXR1、MaPDS1、MaZDS1和MaSPL16表达的激活诱导香蕉果实中类胡萝卜素的产生。