Dataset Information

Computational and experimental analysis of microsatellites in rice (Oryza sativa L.): frequency, length variation, transposon associations, and genetic marker potential.

ABSTRACT: A total of 57.8 Mb of publicly available rice (Oryza sativa L.) DNA sequence was searched to determine the frequency and distribution of different simple sequence repeats (SSRs) in the genome. SSR loci were categorized into two groups based on the length of the repeat motif. Class I, or hypervariable markers, consisted of SSRs > or =20 bp, and Class II, or potentially variable markers, consisted of SSRs > or =12 bp <20 bp. The occurrence of Class I SSRs in end-sequences of EcoRI- and HindIII-digested BAC clones was one SSR per 40 Kb, whereas in continuous genomic sequence (represented by 27 fully sequenced BAC and PAC clones), the frequency was one SSR every 16 kb. Class II SSRs were estimated to occur every 3.7 kb in BAC ends and every 1.9 kb in fully sequenced BAC and PAC clones. GC-rich trinucleotide repeats (TNRs) were most abundant in protein-coding portions of ESTs and in fully sequenced BACs and PACs, whereas AT-rich TNRs showed no such preference, and di- and tetranucleotide repeats were most frequently found in noncoding, intergenic regions of the rice genome. Microsatellites with poly(AT)n repeats represented the most abundant and polymorphic class of SSRs but were frequently associated with the Micropon family of miniature inverted-repeat transposable elements (MITEs) and were difficult to amplify. A set of 200 Class I SSR markers was developed and integrated into the existing microsatellite map of rice, providing immediate links between the genetic, physical, and sequence-based maps. This contribution brings the number of microsatellite markers that have been rigorously evaluated for amplification, map position, and allelic diversity in Oryza spp. to a total of 500.

SUBMITTER: Temnykh S

PROVIDER: S-EPMC311097 | biostudies-literature | 2001 Aug

REPOSITORIES: biostudies-literature

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Computational and experimental analysis of microsatellites in rice (Oryza sativa L.): frequency, length variation, transposon associations, and genetic marker potential.

Temnykh S S DeClerck G G Lukashova A A Lipovich L L Cartinhour S S McCouch S S

Genome research 20010801 8

A total of 57.8 Mb of publicly available rice (Oryza sativa L.) DNA sequence was searched to determine the frequency and distribution of different simple sequence repeats (SSRs) in the genome. SSR loci were categorized into two groups based on the length of the repeat motif. Class I, or hypervariable markers, consisted of SSRs > or =20 bp, and Class II, or potentially variable markers, consisted of SSRs > or =12 bp <20 bp. The occurrence of Class I SSRs in end-sequences of EcoRI- and HindIII-dig ...[more]

PMID: 11483586

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Project description:The rice root system consists of two types of lateral roots, indeterminate larger L-types capable of further branching, and determinate, short, unbranched S-types. L-type laterals correspond to the typical lateral roots of cereals whereas S-type laterals are unique to rice. Both types contribute to nutrient and water uptake and genotypic variation for density and length of these laterals could be exploited in rice improvement to enhance adaptations to nutrient and water-limited environments. Our objectives were to determine how best to screen for lateral root density and length and to identify markers linked to genotypic variation for these traits. Using different growing media showed that screening in nutrient solution exposed genotypic variation for S-type and L-type density, but only the lateral roots of soil-grown plants varied for their lengths. A QTL mapping population developed from parents contrasting for lateral root traits was grown in a low-P field, roots were sampled, scanned and density and length of lateral roots measured. One QTL each was detected for L-type density (LDC), S-type density on crown root (SDC), S-type density on L-type (SDL), S-type length on L-type (SLL), and crown root number (RNO). The QTL for LDC on chromosome 5 had a major effect, accounting for 46% of the phenotypic variation. This strong positive effect was confirmed in additional field experiments, showing that lines with the donor parent allele at qLDC5 had 50% higher LDC. Investigating the contribution of lateral root traits to P uptake using stepwise regressions indicated LDC and RNO were most influential, followed by SDL. Simulating effects of root trait differences conferred by the main QTL in a P uptake model confirmed that qLDC5 was most effective in improving P uptake followed by qRNO9 for RNO and qSDL9 for S-type lateral density on L-type laterals. Pyramiding qLDC5 with qRNO9 and qSDL9 would be possible given that trade-offs between traits were not detected. Phenotypic selection for the RNO trait during variety development would be feasible, however, the costs of doing so reliably for lateral root density traits is prohibitive and markers identified here therefore provide the first opportunity to incorporate such traits into a breeding program.

Dataset Information

Computational and experimental analysis of microsatellites in rice (Oryza sativa L.): frequency, length variation, transposon associations, and genetic marker potential.

Publications

Computational and experimental analysis of microsatellites in rice (Oryza sativa L.): frequency, length variation, transposon associations, and genetic marker potential.

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