Table_6_Overexpression of a Banana Aquaporin Gene MaPIP1;1 Enhances Tolerance to Multiple Abiotic Stresses in Transgenic Banana and Analysis of Its Interacting Transcription Factors.XLSX

Aquaporins can improve the ability of plants to resist abiotic stresses, but the mechanism is still not completely clear. In this research, overexpression of MaPIP1;1 in banana improved tolerance to multiple stresses. The transgenic plants resulted in lower ion leakage and malondialdehyde content, while the proline, chlorophyll, soluble sugar, and abscisic acid (ABA) contents were higher. In addition, under high salt and recovery conditions, the content of Na+ and K+ is higher, also under recovery conditions, the ratio of K+/Na+ is higher. Finally, under stress conditions, the expression levels of ABA biosynthesis and response genes in the transgenic lines are higher than those of the wild type. In previous studies, we proved that the MaMADS3 could bind to the promoter region of MaPIP1;1, thereby regulating the expression of MaPIP1;1 and affecting the drought tolerance of banana plants. However, the mechanism of MaPIP1;1 gene response to stress under different adversity conditions might be regulated differently. In this study, we proved that some transcription factor genes, including MaERF14, MaDREB1G, MaMYB1R1, MaERF1/39, MabZIP53, and MaMYB22, showed similar expression patterns with MaPIP1;1 under salt or cold stresses, and their encoded proteins could bind to the promoter region of MaPIP1;1. Here we proposed a novel MaPIP1;1-mediated mechanism that enhanced salt and cold tolerance in bananas. The results of this study have enriched the stress-resistant regulatory network of aquaporins genes and are of great significance for the development of molecular breeding strategies for stress-resistant fruit crops.

水通道蛋白（Aquaporins）可提升植物抵御非生物胁迫的能力，但其具体分子机制尚未完全阐明。本研究中，在香蕉中过表达MaPIP1;1基因可提高植株对多种非生物胁迫的耐受性。与野生型相比，转基因植株的离子渗漏与丙二醛含量更低，而脯氨酸、叶绿素、可溶性糖以及脱落酸（ABA）含量更高。此外，在高盐胁迫及恢复培养条件下，转基因植株的钠离子（Na+）与钾离子（K+）含量均更高；恢复培养条件下，其K+/Na+比值也更高。最后，在胁迫条件下，转基因株系中脱落酸生物合成与应答基因的表达水平显著高于野生型。
前期研究中，我们已证实MaMADS3可结合MaPIP1;1的启动子区域，进而调控MaPIP1;1的表达并影响香蕉植株的耐旱性。但MaPIP1;1基因在不同逆境条件下响应胁迫的分子机制可能存在差异。
本研究中，我们证实包括MaERF14、MaDREB1G、MaMYB1R1、MaERF1/39、MabZIP53及MaMYB22在内的多种转录因子基因，在盐胁迫或冷胁迫下的表达模式与MaPIP1;1高度相似，且其编码蛋白可结合MaPIP1;1的启动子区域。本研究提出了一种全新的MaPIP1;1介导的香蕉耐盐与耐冷调控机制。本研究结果丰富了水通道蛋白基因的抗逆调控网络，为抗逆果树作物的分子育种策略开发提供了重要理论依据。