The Endophytic Fungus Piriformospora indica Reprograms Banana to Cold Resistance.

Dan Li,Shuting Zhang,Zhongxiong Lai,Bin Wang,Chunzhen Cheng,David Mahoudjro Bodjrenou,Hong Pan,Kai-Wun Yeh

doi:10.3390/ijms22094973

Abstract

Banana (Musa spp.), one of the most important fruits worldwide, is generally cold sensitive. In this study, by using the cold-sensitive banana variety Tianbaojiao (Musa acuminate) as the study material, we investigated the effects of Piriformospora indica on banana cold resistance. Seedlings with and without fungus colonization were subjected to 4 °C cold treatment. The changes in plant phenotypes, some physiological and biochemical parameters, chlorophyll fluorescence parameters, and the expression of eight cold-responsive genes in banana leaves before and after cold treatment were measured. Results demonstrated that P. indica colonization reduced the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) but increased the activities of superoxide dismutase (SOD) and catalase (CAT) and the contents of soluble sugar (SS) and proline. Noteworthily, the CAT activity and SS content in the leaves of P. indica-colonized banana were significant (p < 0.05). After 24 h cold treatment, the decline in maximum photochemistry efficiency of photosystem II (Fv/Fm), photochemical quenching coefficient (qP), efficient quantum yield [Y(II)], and photosynthetic electron transport rate (ETR) in the leaves of P. indica-colonized banana was found to be lower than in the non-inoculated controls (p < 0.05). Moreover, although the difference was not significant, P. indica colonization increased the photochemical conversion efficiency and electron transport rate and alleviated the damage to the photosynthetic reaction center of banana leaves under cold treatment to some extent. Additionally, the expression of the most cold-responsive genes in banana leaves was significantly induced by P. indica during cold stress (p < 0.05). It was concluded that P. indica confers banana with enhanced cold resistance by stimulating antioxidant capacity, SS accumulation, and the expression of cold-responsive genes in leaves. The results obtained from this study are helpful for understanding the P. indica-induced cold resistance in banana.

Highlights

Accumulated reports have shown that the symbiotic interaction between host plants and some of their endophyte microorganisms can confer the host plants with stress tolerance or resistance [1,2]
Trypan blue staining results showed that the chlamydospores and hyphae of P. indica colonized successfullyinin the banana root cortex and intracellularly colonized successfully the banana root cortex cellscells inter-interand intracellularly
We first investigated the influence of P. indica colonization on banana cold resistance

Summary

Introduction

Accumulated reports have shown that the symbiotic interaction between host plants and some of their endophyte microorganisms can confer the host plants with stress tolerance or resistance [1,2]. Among these beneficial microorganisms, Piriformospora indica ( named Serendipita indica) is one of the most focused on members. In 2015, China’s banana planting area was about 410,000 hectares, with an annual output of more than 12 million tons. In 2016, the planting area reduced to about 380,000 hectares, and the annual output dropped sharply to 8.93 million tons, affected by several factors, including cold snaps [11,12]. Improving cold resistance is essential for the healthy development of the banana industry

Methods

Results

Conclusion