Abstract
Boosting cold stress tolerance in crop plants can minimize stress-mediated yield losses. Asian rice (Oryza sativa L.), one of the most consumed cereal crops, originated from subtropical regions and is generally sensitive to low temperature environments. Within the two subspecies of rice, JAPONICA, and INDICA, the cold tolerance potential of its accessions is highly variable and depends on their genetic background. Yet, cold stress tolerance response mechanisms are complex and not well understood. This study utilized 370 accessions from the Rice Diversity Panel 1 (RDP1) to investigate and correlate four cold stress tolerance response phenotypes: membrane damage, seedling survivability, and catalase and anthocyanin antioxidative activity. Most JAPONICA accessions, and admixed accessions within JAPONICA, had lower membrane damage, higher antioxidative activity, and overall, higher seedling survivability compared to INDICA accessions. Genome-wide association study (GWAS) mapping was done using the four traits to find novel quantitative trait loci (QTL), and to validate and fine-map previously identified QTL. A total of 20 QTL associated to two or more traits were uncovered by our study. Gene Ontology (GO) term enrichment analyses satisfying four layers of filtering retrieved three potential pathways: signal transduction, maintenance of plasma membrane and cell wall integrity, and nucleic acids metabolism as general mechanisms of cold stress tolerance responses involving antioxidant activity.
Highlights
IntroductionCrop plants are constantly exposed to a broad range of abiotic factors such as extreme temperatures, high salinity, or water deficit, all of which negatively affect growth and development leading to a significant reduction in productivity [1,2]
This classification was further supported by a high degree of consistency between Low Temperature Seedling Survivability (LTSS) results reported by Shimoyama et al 2020 [40] and results shown here using the same Rice Diversity Panel 1 (RDP1) accessions (Supplementary Figure S3)
Since the major goal of this study was to assess the contribution of antioxidant activity to membrane integrity and seedling survivability during chilling stress, we assigned Multiple-Phenotype (MP) quantitative trait loci (QTL) to regions that had at least one antioxidant activity QTL overlapping with other cold stress response
Summary
Crop plants are constantly exposed to a broad range of abiotic factors such as extreme temperatures, high salinity, or water deficit, all of which negatively affect growth and development leading to a significant reduction in productivity [1,2]. It is crucial to increase the cold tolerance of a cold sensitive crop such as rice to better cope with cold temperature exposures during critical physiological stages of development [5,6,7,8]. Seeds were germinated in distilled water at 37 ◦ C in the dark for 48 h in petri dishes with 0.1% bleach solution to prevent bacterial contamination. Two cold tolerance checks for growth conditions were cold tolerant temperate japonica accession
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