Abstract
Salinity tolerance is an important quality for European rice grown in river deltas. We evaluated the salinity tolerance of a panel of 235 temperate japonica rice accessions genotyped with 30,000 SNP markers. The panel was exposed to mild salt stress (50 mM NaCl; conductivity of 6 dS m-1) at the seedling stage. Eight different root and shoot growth parameters were measured for both the control and stressed treatments. The Na+ and K+ mass fractions of the stressed plants were measured using atomic absorption spectroscopy. The salt treatment affected plant growth, particularly the shoot parameters. The panel showed a wide range of Na+/K+ ratio and the temperate accessions were distributed over an increasing axis, from the most resistant to the most susceptible checks. We conducted a genome-wide association study on indices of stress response and ion mass fractions in the leaves using a classical mixed model controlling structure and kinship. A total of 27 QTLs validated by sub-sampling were identified. For indices of stress responses, we also used another model that focused on marker × treatment interactions and detected 50 QTLs, three of which were also identified using the classical method. We compared the positions of the significant QTLs to those of approximately 300 genes that play a role in rice salt tolerance. The positions of several QTLs were close to those of genes involved in calcium signaling and metabolism, while other QTLs were close to those of kinases. These results reveal the salinity tolerance of accessions with a temperate japonica background. Although the detected QTLs must be confirmed by other approaches, the number of associations linked to candidate genes involved in calcium-mediated ion homeostasis highlights pathways to explore in priority to understand the salinity tolerance of temperate rice.
Highlights
In Europe, rice is grown on approximately 437,000 ha [1]
LA (-51.2%) and SHOOT (-36.5%) were the traits most impacted by salinity stress, followed by longest leaf (LL) (-27.0%) and ROOT (-25.7%)
Based on the results of the two extreme checks (Nona Bokra and IR29) in which the ion mass fractions were measured under both control and stressed conditions, the mean increase in Na+ leaf content varied from 400% (Nona Bokra) to 2000% (IR29), while the mean decrease in K+ leaf content varied only from 35% (Nona Bokra) to 56% (IR29)
Summary
In Europe, rice is grown on approximately 437,000 ha [1]. Italy (220,000 ha) and Spain (110,000 ha) are the main producers, while Greece, Portugal and France are smaller producers (each under 30,000 ha). European rice is grown under permanently flooded conditions. The irrigation water comes from rivers, such as the Poin Italy, the Ebro in Spain and the Rhone in France. European rice is partly grown in river flood plains, as in Italy, and partly in river deltas. In areas below sea level, rice soils are prone to high salinity levels. The risk of soil salinization is increasing with observed decreases in river flow due to climate change [2,3,4] and with the potential development of cropping systems without permanent flooding such as the alternate wetting and drying system aimed at economizing water [5,6,7]. Soil salinity can be maintained at manageable levels using water management techniques to leach salt from topsoil [8,9], the use of rice varieties that are tolerant to salinity has been considered as a protective option
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
