Physiological response and transcriptome analysis of Prunus mume to early salt stress

Xiujun Wang,Zhenqi Song,Yujing Ti,Yuxia Liu,Qingwei Li

doi:10.1007/s13562-021-00680-2

Abstract

AbstractSoil salinisation is an important factor limiting the cultivation and distribution of Prunus mume. Therefore, identifying the regulation mechanism of salt tolerance of P. mume will promote its cultivation and molecular breeding. In this study, the garden tree species P. mume ‘Meiren’ was investigated, with a soil NaCl content (w/w) of 0.3%. Photosynthetic gas exchange parameters, relative electrical conductivity, malondialdehyde, osmoregulation substances, and antioxidant enzyme activity were measured in the early (3d), middle (10d), and late (30d) stages of stress. Salt treatment was applied for 0 h, 6 h, 24 h, and 72 h; following this, the gene library was constructed from the leaves. The results showed that the CBL-CIPK, mitogen-activated protein kinase, calcium-dependent protein kinase, and abscisic acid signalling pathways were involved in salt stress signal transduction of P. mume. Furthermore, bHLH, WRPK, ERF, and MYB were identified as potential key transcription factor families of salt tolerance in P. mume. Combined with determined physiological responses, the results showed that early salt stress inhibited the activities of RuBisCO, chlorophyll synthase, glutamyl tRNA reductase, divinyl reductase, and magnesium chelatase; resultantly, this led to a reduction in the photosynthetic rate. Also, it was found that P5CS, SS, LEA, and dehydrin regulated the synthesis of proline, soluble sugar, and macromolecular protein to alleviate osmotic stress. POD gene plays an important role in scavenging reactive oxygen species due to its regulation of POD activity. The findings of this research reveal the internal mechanism of the physiological response and provide a foundation for the construction of a genetic regulatory network in response to salt stress in P. mume.

Highlights

The salinisation of soil has become a major global resource concern and environmental issue
The results showed that the CBL-CIPK, mitogen-activated protein kinase, calcium-dependent protein kinase, and abscisic acid signalling pathways were involved in salt stress signal transduction of P. mume
In the early period of stress, the photosynthetic gas exchange parameters, relative conductivity, MDA, and soluble sugar content changed significantly (P B 0.05); in the mid-stage of stress, the indicators all changed with the exception of Ci, which returned to a normal value; in the late stage of stress, soluble sugar and Ci returned to normal levels, while Pn, Tr, and superoxide dismutase (SOD) showed values lower than those of control group, and relative conductivity, MDA, free proline, and soluble protein were higher than normal levels

Summary

Introduction

The salinisation of soil has become a major global resource concern and environmental issue. The salt content in soil affects the geographical distribution of plants in nature, whilst limiting the productivity of plants (Zhu 2016; Agarwal et al 2020). Cl- affect plant metabolism and reduce the rate of photosynthesis, and slow down plant growth (Waqas et al 2021; Zhao et al 2020). In the process of long-term evolution and environmental adaptation, plants have formed a series of physiological and molecular mechanisms in response to salt stress, which can be divided into two categories: the first is salt tolerance, whereby effector molecules directly participate in changes to the physiological cellular metabolism, and contribute to salt tolerance, and the second is regulatory molecules, which are located upstream of effector molecules and are involved in signal transduction, primarily including various kinases and transcription factors comprising the signal transduction system (Chen et al 2021). Soil salinity and alkali content are important factors that can limit the distribution of P. mume (Yang et al 2018; Li 2009).

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Conclusion