MaMAPK3-MaICE1-MaPOD P7 pathway, a positive regulator of cold tolerance in banana

Jie Gao,Ou Sheng,Tao Dong,Weidi He,Fangcheng Bi,Ganjun Yi,Guiming Deng,Huijun Gao,Chunhua Hu,Chunyu Li,Tongxin Dou,Sheng Zhang,Qiaosong Yang

doi:10.1186/s12870-021-02868-z

Abstract

BackgroundBanana is a tropical fruit with a high economic impact worldwide. Cold stress greatly affects the development and production of banana.ResultsIn the present study, we investigated the functions of MaMAPK3 and MaICE1 involved in cold tolerance of banana. The effect of RNAi of MaMAPK3 on Dajiao (Musa spp. ‘Dajiao’; ABB Group) cold tolerance was evaluated. The leaves of the MaMAPK3 RNAi transgenic plants showed wilting and severe necrotic symptoms, while the wide-type (WT) plants remained normal after cold exposure. RNAi of MaMAPK3 significantly changed the expressions of the cold-responsive genes, and the oxidoreductase activity was significantly changed in WT plants, while no changes in transgenic plants were observed. MaICE1 interacted with MaMAPK3, and the expression level of MaICE1 was significantly decreased in MaMAPK3 RNAi transgenic plants. Over-expression of MaICE1 in Cavendish banana (Musa spp. AAA group) indicated that the cold resistance of transgenic plants was superior to that of the WT plants. The POD P7 gene was significantly up-regulated in MaICE1-overexpressing transgenic plants compared with WT plants, and the POD P7 was proved to interact with MaICE1.ConclusionsTaken together, our work provided new and solid evidence that MaMAPK3-MaICE1-MaPOD P7 pathway positively improved the cold tolerance in monocotyledon banana, shedding light on molecular breeding for the cold-tolerant banana or other agricultural species.

Highlights

Banana is a tropical fruit with a high economic impact worldwide
RNAi of MaMAPK3 decreases the cold tolerance of transgenic plants We identified 20 individual equivalent transcripts in Musa genome using the sequences of all Arabidopsis thaliana mitogen-activated protein kinase (MAPK) genes as a reference (Fig. S1A)
The open reading frame (ORF) of MaMAPK3 was in frame with the green fluorescent protein (GFP) N-terminus and C-terminus, and no signal was detected in the MaMAPK3-GFP fusion construct

Summary

Introduction

Cold stress greatly affects the development and production of banana. The Musa originated in Southeast Asia and the Western Pacific region, and the domestication process started about 7000 years ago [2]. It involves hybridizations between diverse species and subspecies fostered by human migrations [3], selection of seedless diploid and triploid, and parthenocarpic hybrids widely dispersed by vegetative propagation. As an important and restricting factor, temperature determines the development and output of banana, since its growth and production will be irreversibly affected when the temperature is lower than 12 °C [8]. ‘Dajiao’; ABB Group) has a stronger cold tolerance compared with Cavendish Banana Due to the highly heterozygous genotype and complex genetic background in molecular biology studies, such as gene function verification related to important traits, the study on cold resistance of bananas has been a challenge for a long time [1, 2]

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