Photosynthetic Regulation Under Salt Stress and Salt-Tolerance Mechanism of Sweet Sorghum.

Zhen Yang,Qi Xie,Lu-Ning Liu,Jin-Lu Li,Na Sui

doi:10.3389/fpls.2019.01722

Abstract

Sweet sorghum is a C4 crop with the characteristic of fast-growth and high-yields. It is a good source for food, feed, fiber, and fuel. On saline land, sweet sorghum can not only survive, but increase its sugar content. Therefore, it is regarded as a potential source for identifying salt-related genes. Here, we review the physiological and biochemical responses of sweet sorghum to salt stress, such as photosynthesis, sucrose synthesis, hormonal regulation, and ion homeostasis, as well as their potential salt-resistance mechanisms. The major advantages of salt-tolerant sweet sorghum include: 1) improving the Na+ exclusion ability to maintain ion homeostasis in roots under salt-stress conditions, which ensures a relatively low Na+ concentration in shoots; 2) maintaining a high sugar content in shoots under salt-stress conditions, by protecting the structures of photosystems, enhancing photosynthetic performance and sucrose synthetase activity, as well as inhibiting sucrose degradation. To study the regulatory mechanism of such genes will provide opportunities for increasing the salt tolerance of sweet sorghum by breeding and genetic engineering.

Highlights

Soil salinization is a compelling environmental problem worldwide (Landi et al, 2017)
A limited number of crops can survive in saline land, which can lead to desertification (Flowers and Colmer, 2010)
A few genes in M-81E mapped to the photosynthesis pathway were affected by salt stress, and 2 genes related to the stable assembly of the oxygen-evolving complex and ATP synthase were up-regulated under salt stress (Sui et al, 2015). These results suggest that salt stress could affect the assembly of photosystems and reduce the efficiency of electron transport, resulting in the decrease of ATP and NADPH in plants under salt stress

Summary

INTRODUCTION

Soil salinization is a compelling environmental problem worldwide (Landi et al, 2017). It has been reported that the increase in the Na+ concentration and the decrease in the K+ concentration in saltsensitive sweet sorghum germplasms during salt stress could lead to the decreased levels of several synthesis and metabolism actions, such as photosynthesis and nutrient transport (Sui et al, 2015; Yang et al, 2018), impeding the growth of both roots and shoots (Almodares et al, 2014). These effects appear to be more significant in salt-sensitive sweet sorghum inbred (Yang et al, 2018). The absence of an efficient sweet sorghum transformation protocol represents a major bottleneck in salt-tolerance genetic engineering (Raghuwanshi and Birch, 2010; Liu and Godwin, 2012)

CONCLUSION AND PERSPECTIVES

Findings

ETHICS STATEMENT