title: Genetic differentiation revealed by selective loci of drought-responding EST-SSRs between upland and lowland rice in China.
abstract: Upland and lowland rice (Oryza sativa L.) represent two of the most important rice ecotypes adapted to ago-ecosystems with contrasting soil-water conditions. Upland rice, domesticated in the water-limited environment, contains valuable drought-resistant characters that can be used in water-saving breeding. Knowledge about the divergence between upland and lowland rice will provide valuable cues for the evolution of drought-resistance in rice. Genetic differentiation between upland and lowland rice was explored by 47 Simple Sequence Repeats (SSRs) located in drought responding expressed sequence tags (ESTs) among 377 rice landraces. The morphological traits of drought-resistance were evaluated in the field experiments. Different outlier loci were detected in the japonica and indica subspecies, respectively. Considerable genetic differentiation between upland and lowland rice on these outlier loci was estimated in japonica (Fst = 0.258) and indica (Fst = 0.127). Furthermore, populations of the upland and lowland ecotypes were clustered separately on these outlier loci. A significant correlation between genetic distance matrices and the dissimilarity matrices of drought-resistant traits was determined, indicating a certain relationship between the upland-lowland rice differentiation and the drought-resistance. Divergent selections occur between upland and lowland rice on the drought-resistance as the Qsts of some drought-resistant traits are significantly higher than the neutral Fst. In addition, the upland- and lowland-preferable alleles responded differently among ecotypes or allelic types under osmotic stress. This shows the evolutionary signature of drought resistance at the gene expression level. The findings of this study can strengthen our understanding of the evolution of drought-resistance in rice with significant implications in the improvement of rice drought-resistance.
authors.affiliation: Shanghai Agrobiological Gene Center, Shanghai, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xia
authors.affiliation: Shanghai Agrobiological Gene Center, Shanghai, China.
authors.forename: Xiaoguo
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Shanghai Agrobiological Gene Center, Shanghai, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.affiliation: Shanghai Agrobiological Gene Center, Shanghai, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Gao
authors.affiliation: Shanghai Agrobiological Gene Center, Shanghai, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Yang
authors.affiliation: Shanghai Agrobiological Gene Center, Shanghai, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Long
authors.affiliation: Center for Watershed Ecology, Institute of Life Science and Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang University, Nanchang, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Rong
authors.affiliation: Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, Fudan University, Shanghai, China.
authors.forename: Baorong
authors.initials: B
authors.lastname: Lu
authors.affiliation: Shanghai Agrobiological Gene Center, Shanghai, China.
authors.forename: Jiajia
authors.initials: J
authors.lastname: Li
authors.affiliation: Shanghai Agrobiological Gene Center, Shanghai, China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Luo
mesh_terms: D000483:Alleles; D002681:China; D016001:Confidence Intervals; D055864:Droughts; D060146:Ecotype; D020224:Expressed Sequence Tags; D014644:Genetic Variation; D005828:Genetics, Population; D018895:Microsatellite Repeats / Q000235:genetics*; D058977:Molecular Sequence Annotation; D012275:Oryza / Q000033:anatomy & histology / Q000235:genetics*; D010802:Phylogeny; D025341:Principal Component Analysis; D040641:Quantitative Trait Loci / Q000235:genetics*