Physiological and Proteomic Analyses Reveal Adaptive Mechanisms of Ryegrass (Annual vs. Perennial) Seedlings to Salt Stress

Xiaoyuan Peng,Dafu Yu,Jixiang Lin,Jinghong Wang,Junxin Yan,Na Zhang

doi:10.3390/agronomy9120843

Abstract

Ryegrass has a relatively high salt tolerance and is considered to be a promising species for both foraging and turf purposes in salt-affected soils in China. While annual ryegrass and perennial ryegrass are two different species, they have similar genomes. However, little is known about their physiological and molecular response mechanisms to salinity stress. Here, biomass, chlorophyll fluorescence, and inorganic ion and organic solute content were measured. 2-DE-based proteomic technology was then used to identify the differentially expressed proteins in the salt-treated seedlings. The results showed that salt stress reduced growth and photosynthesis in the seedlings of both species, but much more so in annual ryegrass. With increasing salinity, the Na+ concentration increased while the K+ concentration decreased in both species, and the sugars and proline increased as the primary organic solutes used to cope with osmotic stress. Additionally, proteomic analysis revealed 33 and 37 differentially expressed proteins in annual and perennial ryegrass, respectively. Most of the identified proteins were involved in carbohydrate and energy metabolism, photosynthesis, genetic information processes, amino acid metabolism, stress defense, and protein synthesis and folding. The results suggest that the two-ryegrass species had different physiological and proteomic responses. These findings can provide new insights into physiological mechanisms by which ryegrass species respond to salt stress.

Highlights

Annual ryegrass (Lolium multiflorum Lam.) and perennial ryegrass (Lolium perenne L.) are widely distributed in Europe, North Africa, and temperate Asia [1]
The results showed that there were six proteins shared in common between annual and perennial ryegrass, three of which had opposite accumulation patterns in the two species (Figure 4C), which indicated that annual ryegrass and perennial ryegrass have different mechanisms by which they respond to salt stress
The seedling weights in both species decreased with increasing salinity, but the decrease was greater in the dry weight of annual ryegrass at 200 mM salinity (Table 1), which indicated that salt tolerance of the two ryegrasses were different

Summary

Introduction

Annual ryegrass (Lolium multiflorum Lam.) and perennial ryegrass (Lolium perenne L.) are widely distributed in Europe, North Africa, and temperate Asia [1] These two species have very similar genomes but have great differences in morphological characteristics and uses. Perennial ryegrass is valued for high yield potential as forage grass, but this species can be used for a variety of turf applications (e.g., home lawns, fairways, athletic fields, and golf courses) [4,5]. Both ryegrasses have good salt tolerance and are considered promising in the bioremediation of salt-affected soil in northeastern China.

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