Dataset Information

Mapping of quantitative trait loci underlying cold tolerance in rice seedlings via high-throughput sequencing of pooled extremes.

ABSTRACT: Low temperature is a major limiting factor in rice growth and development. Mapping of quantitative trait loci (QTLs) controlling cold tolerance is important for rice breeding. Recent studies have suggested that bulked segregant analysis (BSA) combined with next-generation sequencing (NGS) can be an efficient and cost-effective way for QTL mapping. In this study, we employed NGS-assisted BSA to map QTLs conferring cold tolerance at the seedling stage in rice. By deep sequencing of a pair of large DNA pools acquired from a very large F3 population (10,800 individuals), we obtained ?450,000 single nucleotide polymorphisms (SNPs) after strict screening. We employed two statistical methods for QTL analysis based on these SNPs, which yielded consistent results. Six QTLs were mapped on chromosomes 1, 2, 5, 8 and 10. The three most significant QTLs on chromosomes 1, 2 and 8 were validated by comparison with previous studies. Two QTLs on chromosomes 2 and 5 were also identified previously, but at the booting stage rather than the seedling stage, suggesting that some QTLs may function at different developmental stages, which would be useful for cold tolerance breeding in rice. Compared with previously reported QTL mapping studies for cold tolerance in rice based on the traditional approaches, the results of this study demonstrated the advantages of NGS-assisted BSA in both efficiency and statistical power.

SUBMITTER: Yang Z

PROVIDER: S-EPMC3728330 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Mapping of quantitative trait loci underlying cold tolerance in rice seedlings via high-throughput sequencing of pooled extremes.

Yang Zemao Z Huang Daiqing D Tang Weiqi W Zheng Yan Y Liang Kangjing K Cutler Adrian J AJ Wu Weiren W

PloS one 20130730 7

Low temperature is a major limiting factor in rice growth and development. Mapping of quantitative trait loci (QTLs) controlling cold tolerance is important for rice breeding. Recent studies have suggested that bulked segregant analysis (BSA) combined with next-generation sequencing (NGS) can be an efficient and cost-effective way for QTL mapping. In this study, we employed NGS-assisted BSA to map QTLs conferring cold tolerance at the seedling stage in rice. By deep sequencing of a pair of large ...[more]

PMID: 23935868

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Project description:BACKGROUND:Developing chilling tolerant accessions of domesticated Asian rice is a potential source of significant crop improvement. The uniquely chilling sensitive nature of the tropically originating Oryza sativa make it the most important cereal crop that can gain significantly from improved tolerance to low temperatures. However, mechanisms underlying this complex trait are not fully understood. Oryza sativa has two subspecies with different levels of chilling tolerance, JAPONICA and INDICA, providing an ideal tool to investigate mechanistic differences in the chilling stress tolerance responses within this important crop species. RESULTS:The Rice Diversity Panel 1 (RDP1) was used to investigate a core set of Oryza sativa accessions. The tools available for this panel allowed for a comprehensive analysis of two chilling tolerance traits at multiple temperatures across a 354-cultivar subset of the RDP1. Chilling tolerance trait values were distributed as mostly subpopulation specific clusters of Tolerant, Intermediate, and Sensitive accessions. Genome-wide association study (GWAS) mapping approaches using all 354 accessions yielded a total of 245 quantitative trait loci (QTL), containing 178 unique QTL covering 25% of the rice genome, while 40 QTL were identified by multiple traits. QTL mappings using subsets of rice accession clusters yielded another 255 QTL, for a total of 500 QTL. The genes within these multiple trait QTL were analyzed for Gene Ontology (GO) term and potential pathway enrichments. Terms related to "carbohydrate biosynthesis", "carbohydrate transmembrane transport", "small molecule protein modification", and "plasma membrane" were enriched from this list. Filtering was done to identify more likely candidate pathways involved in conferring chilling tolerance, resulting in enrichment of terms related to "Golgi apparatus", "stress response", "transmembrane transport", and "signal transduction". CONCLUSIONS:Taken together, these GO term clusters revealed a likely involvement of Golgi-mediated subcellular and extracellular vesicle and intracellular carbohydrate transport as a general cold stress tolerance response mechanism to achieve cell and metabolic homeostasis under chilling stress.

Project description:Cucumber (Cucumis sativus L.) is an economically important vegetable crop worldwide, but it is sensitive to low temperatures. Cucumber seedlings exposed to long-term low temperature stress (LT), i.e., below 20°C during the day, and 8°C at night, exhibit leaf yellowing, accelerated senescence, and reduced yield, therefore posing a threat to cucumber production. Studying the underlying mechanisms involved in LT tolerance in cucumber seedlings, and developing germplasm with improved LT-tolerance could provide fundamental solutions to the problem. In this study, an F2 population was generated from two parental lines, "CG104" (LT-tolerant inbred line) and "CG37" (LT-sensitive inbred line), to identify loci that are responsible for LT tolerance in cucumber seedlings. Replicated phenotypic analysis of the F2-derived F3 family using a low-temperature injury index (LTII) suggested that the LT tolerance of cucumber seedlings is controlled by multiple genes. A genetic map of 990.8 cM was constructed, with an average interval between markers of 5.2 cM. One quantitative trait loci (QTL) named qLTT5.1 on chromosome 5, and two QTLs named qLTT6.1 and qLTT6.2 on chromosome 6 were detected. Among them, qLTT6.2 accounted for 26.8 and 24.1% of the phenotypic variation in two different experiments. Single-nucleotide polymorphism (SNP) variations within the region of qLTT6.2 were analyzed using two contrasting in silico bulks generated from the cucumber core germplasm. Result showed that 214 SNPs were distributed within the 42-kb interval, containing three candidate genes. Real-time quantitative reverse transcription PCR and sequence analysis suggested that two genes Csa6G445210, an auxin response factor, and Csa6G445230, an ethylene-responsive transmembrane protein, might be candidate genes responsible for LT tolerance in cucumber seedlings. This study furthers the understanding of the molecular mechanism underlying LT tolerance in cucumber seedlings, and provides new markers for molecular breeding.

Project description:Low temperature significantly affects rice growth and yield. Temperatures lower than 15°C are generally detrimental for germination and uniform seedling stand. To investigate the genetic architecture underlying cold tolerance during germination in rice, we conducted a genome-wide association study using a novel diversity panel of 257 rice accessions from around the world and the 7K SNP marker array. Phenotyping was conducted in controlled growth chambers under dark conditions at 13°C. The rice accessions were measured for low-temperature germinability, germination index, coleoptile length under cold stress, plumule length at 4-day recovery, and plumule length recovery rate. A total of 51 QTLs were identified at p < 0.001 and 17 QTLs were identified using an FDR < 0.05 across the different chilling indices with the whole panel of accessions. At the threshold of p < 0.001, a total of 20 QTLs were identified in the subset of japonica accessions, while 9 QTLs were identified in the subset of indica accessions. Considering the recurring SNPs and linked SNPs across different chilling indices, we identified 31 distinct QTL regions in the whole panel, 13 QTL regions in the japonica subset, and 7 distinct QTL regions in the indica subset. Among these QTL regions, three regions were common between the whole panel and japonica, three regions were common between the whole panel and indica, and one region was common between indica and japonica. A subset of QTL regions was potentially colocalized with previously identified genes and QTLs, including 10 from the japonica subset, 4 from the indica subset, and 6 from the whole panel. On the other hand, a total of 21 potentially novel QTL regions from the whole panel, 10 from the japonica subset, and 1 from the indica subset were identified. The results of our study provide useful information on the genetic architecture underlying cold tolerance during germination in rice, which in turn can be used for further molecular study and crop improvement for low-temperature stressed environments.

Project description:In this study, the cold-tolerance capacity of 133 varieties of weedy rice was evaluated based on the comprehensive evaluation index D, with Kongyu 131 used as a cold-tolerant control. A total of 39.8% of the 133 varieties were considered 'strong', indicating that weedy rice populations indeed have relatively strong cold-tolerance capacity as a whole, and the robust cold-tolerant varieties WR29 and WR157 were identified. Regression analysis showed that the metrics including the nitrogen recovery index, superoxide dismutase (SOD) content and malondialdehyde (MDA) content correlated significantly (P < 0.05) with cold tolerance and could be used as indicators of cold tolerance. On the basis of a transcriptome analysis of WR157, a robust cold-tolerant variety identified in this study, a total of 4645 putative DEGs were identified in treated groups compared to the control groups, with 2123 upregulated DEGs and 2522 downregulated DEGs. All upregulated DEGs were enriched on 1388 terms, all downregulated DEGs were enriched on 1566 terms; 911 of the 2123 upregulated DEGs fell into 98 KEGG categories and 1103 of the 2522 downregulated DEGs were in 115 categories. Further analysis showed that GO:0019740 and GO:0006808 are involved in nitrogen utilization; GO:0009269 and GO:0009414 are related to the stress response; and GO:0016491 and GO:0016614 are related to oxidoreductase activity. BACKGROUND: Weedy rice (Oryza) is a related pest species of cultivated rice (Oryza sativa L.) that has strong abiotic stress resistance; however, the comprehensive mechanism governing its cold tolerance is poorly understood. CONCLUSION: Our comprehensive evaluation based on five morphological indices and nine physiological indicators revealed outstanding levels of cold-tolerance capacity among weedy rice varieties from different regions and revealed some terms related to cold tolerance via transcriptome analysis. Our results underscored the reliable evaluation methods for additional cold tolerance studies and revealed several genes related to cold tolerance, which will help researchers breed cultivated rice varieties to increase their cold-tolerance capacity. These traits have the ability to increase seedling survival rate and growth, as well as future yields.

Dataset Information

Mapping of quantitative trait loci underlying cold tolerance in rice seedlings via high-throughput sequencing of pooled extremes.

Publications

Mapping of quantitative trait loci underlying cold tolerance in rice seedlings via high-throughput sequencing of pooled extremes.

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