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

Yi Xu,Juhua Liu,Caihong Jia,Shun Song,Biyu Xu,Wei Hu,Zhiqiang Jin

doi:10.3389/fpls.2021.699230

Abstract

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.

Highlights

Drought, salinity, and cold stresses can cause plants to lose water and severely affect their growth and development
The callus was cut into 2-mm sections and infected with A. tumefaciens EHA105 transformed with the MaPIP1;1pCAMBIA1302 expression vector
251 hygromycin-resistant transgenic lines were obtained, of which 27 lines were further verified by PCR amplification of the GFP gene in the vector

Summary

Introduction

Salinity, and cold stresses can cause plants to lose water and severely affect their growth and development. As the main fruit and crop on a global scale, bananas have made important economic contributions to tropical and subtropical developing countries (Liu et al, 2017). Due to their shallow root system, banana plants are susceptible to drought, salt, and cold stress-induced water shortage conditions, which will greatly reduce the yield and quality of bananas (van Asten et al, 2011; Sreedharan et al, 2013). Plant AQPs can be divided into eight categories, including tonoplast intrinsic proteins (TIPs), plasma membrane intrinsic proteins (PIPs), small basic intrinsic proteins (SIPs), nodulin 26-like intrinsic proteins (NIPs), hybrid intrinsic proteins (HIPs), GlpF-like intrinsic proteins (GIPs), large intrinsic proteins (LIPs), and uncategorized members designated X intrinsic proteins (XIPs), which were based on protein sequence homology and predicted subcellular location (Hussain et al, 2019)

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Results

Conclusion