Increased salt tolerance with overexpression of cation/proton antiporter 1 genes: a meta-analysis.

Yuan-Chun Ma,Robert M Augé,Zong-Ming Max Cheng,Chao Dong

doi:10.1111/pbi.12599

Abstract

SummaryCation/proton antiporter 1 (CPA1) genes encode cellular Na+/H+ exchanger proteins, which act to adjust ionic balance. Overexpression of CPA1s can improve plant performance under salt stress. However, the diversified roles of the CPA1 family and the various parameters used in evaluating transgenic plants over‐expressing CPA1s make it challenging to assess the complex functions of CPA1s and their physiological mechanisms in salt tolerance. Using meta‐analysis, we determined how overexpression of CPA1s has influenced several plant characteristics involved in response and resilience to NaCl stress. We also evaluated experimental variables that favour or reduce CPA1 effects in transgenic plants. Viewed across studies, overexpression of CPA1s has increased the magnitude of 10 of the 19 plant characteristics examined, by 25% or more. Among the ten moderating variables, several had substantial impacts on the extent of CPA1 influence: type of culture media, donor and recipient type and genus, and gene family. Genes from monocotyledonous plants stimulated root K+, root K+/Na+, total chlorophyll, total dry weight and root length much more than genes from dicotyledonous species. Genes transformed to or from Arabidopsis have led to smaller CPA1‐induced increases in plant characteristics than genes transferred to or from other genera. Heterogeneous expression of CPA1s led to greater increases in leaf chlorophyll and root length than homologous expression. These findings should help guide future investigations into the function of CPA1s in plant salt tolerance and the use of genetic engineering for breeding of resistance.

Highlights

Soil salinization is one of the chief abiotic stresses that constrain agriculture worldwide (Cramer et al, 2011), and at least 50% of global agricultural lands are at risk of salinization (Wang et al, 2003)
The most extensively studied gene category in relation to NaCl stress physiology is the family of cation/proton antiporter 1 (CPA1, Brett et al, 2005)
The Cation/proton antiporter 1 (CPA1) gene family belongs to the CPA superfamily and includes the NHX type and Nhap type (Apse et al, 1999; Rodrıguez et al, 2009)

Summary

Introduction

Soil salinization is one of the chief abiotic stresses that constrain agriculture worldwide (Cramer et al, 2011), and at least 50% of global agricultural lands are at risk of salinization (Wang et al, 2003). Understanding the molecular mechanisms of salt stress responses and the functions of genes that regulate responses to salinity will help in designing strategies for development of salt-resistant crop plants. The most extensively studied gene category in relation to NaCl stress physiology is the family of cation/proton antiporter 1 (CPA1, Brett et al, 2005). The CPA1 gene family belongs to the CPA superfamily and includes the NHX type and Nhap type (Apse et al, 1999; Rodrıguez et al, 2009). CPA1 genes encode Na+/H+ exchanger proteins, which modulate ion balance in plant cells (Feki et al, 2014; Fukuda et al, 2004). Many CPA1 genes have been isolated from various plants and several have been overexpressed in model and in crop plants, frequently leading to increased salinity tolerance (51 papers listed in Appendix S1)

Methods

Discussion

Conclusion