Abscisic acid (ABA) is a phytohormone essential for plants to respond to various environmental stresses, and abscisic acid-insensitive 5 (ABI5) is a basic leucine zipper transcription factor of the ABA signaling pathway. Exogenous ABA induces cold tolerance in bananas; however, the role of MaABI5-like in ABA-induced cold tolerance remains unexplored. The present study found that exogenous ABA alleviated chilling injury of ‘Fenjiao’ banana, induced the accumulation of endogenous ABA, unsaturated fatty acids, and flavonoid content, and reduced the saturated fatty acid content. Moreover, ABA treatment up-regulated the transcription levels of MaABI5-like, fatty acid desaturation genes, and flavonoid synthesis-related genes during cold storage. More interestingly, MaABI5-like directly interacted with the promoter of genes related to fatty acid desaturation (MaFAD3-1, MaFAD3-4, MaFAD3-5, MaFAD6-2, MaFAD6-3) and flavonoid synthesis (MaPAL-like, MaPAL-like1, MaC4H-like3, Ma4CL-like1, Ma4CL-like10, MaCHS6-4-like, and MaFLS) and activated their expressions. Furthermore, the transient overexpression of MaABI5-like in ‘Fenjiao’ banana fruit and the ectopic expression in the tomato plants enhanced the cold tolerance and up-regulated fatty acid desaturation and flavonoid synthesis-related gene transcript levels. The reduced expression of MaABI5-like by virus induced gene silencing (VIGS) in ‘Fenjiao’ banana increased the chilling injury and down-regulated the expression of fatty acid desaturation and flavonoid synthesis-related genes. Thus, the study indicates that MaABI5-like regulates ABA-induced cold tolerance by increasing unsaturated fatty acid and flavonoid content.

中文翻译：

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MaABI5 样基因在‘粉椒’蕉果实脱落酸耐寒性中的作用

脱落酸（ABA）是植物响应各种环境胁迫所必需的植物激素，脱落酸不敏感5（ABI5）是ABA信号通路的碱性亮氨酸拉链转录因子。外源ABA诱导香蕉耐寒性；然而，MaABI5-like 在 ABA 诱导的耐寒性中的作用仍未得到探索。本研究发现外源ABA减轻了'粉角'香蕉的冷害，诱导了内源ABA、不饱和脂肪酸和类黄酮含量的积累，并降低了饱和脂肪酸含量。此外，ABA 处理上调了冷藏过程中 MaABI5 样基因、脂肪酸去饱和基因和类黄酮合成相关基因的转录水平。更有趣的是，MaABI5-like 直接与脂肪酸去饱和相关基因（MaFAD3-1、MaFAD3-4、MaFAD3-5、MaFAD6-2、MaFAD6-3）和类黄酮合成（MaPAL-like、MaPAL-like1、MaC4H- like3、Ma4CL-like1、Ma4CL-like10、MaCHS6-4-like 和 MaFLS）并激活它们的表达。此外，MaABI5-like 在 'Fenjiao' 香蕉果实中的瞬时过表达和在番茄植物中的异位表达增强了耐寒性并上调了脂肪酸去饱和和类黄酮合成相关基因转录水平。病毒诱导基因沉默(virus induced gene silencing, VIGS)降低'粉角'香蕉MaABI5-like的表达，增加了冷害，下调了脂肪酸去饱和和类黄酮合成相关基因的表达。因此，