Identification and Characterization of Chromosome Regions Associated With Salinity Tolerance in Rice

Nguyen Thi Thu Thuy,Yoshihiko Hirai,Misato Tokuyasu,Nguyen Sao Mai

doi:10.5539/jas.v10n11p57

Abstract

Rice, the major crop sustaining approximately half the world population, has been extensively reported to be sensitive to saline conditions. However, the genetic and physiological understanding related to long-term salinity stress remains unclear so far. The aim of this study was to evaluate the mechanisms of salinity tolerance in a salinity-tolerant variety of rice, Nona Bokra, and to detect the chromosomal regions responsible for it. We utilized chromosome segment substitution lines (CSSLs) carrying segments from Nona Bokra in the genetic background of a salt-sensitive variety Koshihikari by investigating the plant growth, grain productivity, and ion contents in plants subjected to long-term salinity stress. Comparison of plant growth and grain yield of CSSLs grown under long-term saline conditions suggests that the salinity tolerance of Nona Bokra involves the improvement of plant dry matter, panicle number, and percentage of ripened grains. Nona Bokra has the chromosomal regions for the improvement of the panicle number on chromosome 2 and the percentage of ripened grains on chromosome 6 or 10 under salinity conditions. It was suggested that these chromosomal regions were related to Na+ and Cl- exclusion. Low Na+ and Cl- contents in whole plant at full heading stage would be vital for improving the yield under long-term saline conditions.

Highlights

Rice is one of the principal crops in the world, and it is the single most important source of employment and income in rural Asia (Hoang et al, 2016; Khan et al, 2016)
The results showed: (i) several chromosome segment substitution lines (CSSLs) performed salinity tolerance for higher plant dry weight (Figure 3), grain yield (Figure 4), and yield components (Figuare 5) than those of Koshihikari; (ii) the timing of low Na+ or Cl− contents in whole plant under saline conditions was different among the CSSLs (Figure 6); and, (iii) Na+ and Cl− contents of plants at full heading stage were highly correlated with grain yield and panicle number (Figure7)
The salinity tolerance for the growth and grain yield of six CSSLs selected from the results in 2014 was compared with that of Koshihikari at different growth stages under saline conditions in 2015, five CSSLs, exept for SL516, showed salinity tolerance, showed higher plant dry weight at least in one of the growth stages or in higher grain yield compared to Koshihikari under saline conditions (Figures 3 and 4)

Summary

Introduction

Rice is one of the principal crops in the world, and it is the single most important source of employment and income in rural Asia (Hoang et al, 2016; Khan et al, 2016). The world population is projected to reach 9.1 billion by 2050, and this necessitates an increase in food production by about 70% in order to sustain this large population (Food and Agriculture Organization, 2009; Godfray et al, 2010). It is important to increase rice productivity to meet the demand. Loss of rice yield due to salinity stress is estimated to be between 10% to 80%, and when this is coupled with erratic rainfall, it can reach up to 100% (Vinod et al, 2013). It is essential to enhance the salinity tolerance of rice in order to enable adequate food production for the rice-consuming populations

Objectives

Methods

Results

Discussion

Conclusion