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Nitrogen (N) deficiency is a major yield-limiting factor in rice production. The objective of this study was to identify putative QTLs for low-N stress tolerance of rice, using an advanced backcross population derived from crosses between an indica cultivar '93-11' and a japonica cultivar 'Nipponbare' and genotyped at 250 marker loci. Plant height, maximum root length, root dry weight, shoot dry weight and plant dry weight under two N conditions and their relative traits were used to evaluate low-N tolerance at the seedling stage. A total of 44 QTLs were identified on chromosomes 1, 2, 3, 4, 5, 6, 8 and 9. Eight intervals on five chromosomes were identified to harbour multiple QTLs, suggesting pleiotropism or multigenic effects according to the contributor of alleles. Some QTL clusters were found in the nearby regions of genes associated with N recycling in rice, indicating that the key N metabolism genes might have effects on the expression of QTLs. Several unique QTLs for relative traits were detected, which suggested the specific genetic basis of relative performance. [ABSTRACT FROM AUTHOR]

Abstract: A high-yielding japonica rice variety, Wuyunjing 7, bred in Jiangsu Province, China as a female parent was crossed with a Japanese rice variety Kantou 194, which carries a rice stripe disease resistance gene Stv-bi and a translucent endosperm mutant gene Wx-mq. From F2 generations, a sequence characterized amplified region (SCAR) marker tightly linked with Stv-bi and a cleaved amplified polymorphic sequence (CAPS) marker for Wx-mq were used for marker-assisted selection. Finally, a new japonica rice line, Ning 9108, with excellent agronomic traits was obtained by multi-generational selection on stripe disease resistance and endosperm appearance. The utilization of the markers from genes related to rice quality and disease resistance was helpful not only for establishing a marker-assisted selection system of high-quality and disease resistance for rice but also for providing important intermediate materials and rapid selection method for good quality, disease resistance and high yield in rice breeding. [Copyright &y& Elsevier]

Abstract: The cold tolerance at the bud bursting stage (CTB) was evaluated at 5°C by using a set of 95 chromosome segment substitution lines (CSSLs) derived from an indica rice 9311 and a japonica rice Nipponbare with a genetic background of 9311. The result showed that six CSSLs had slightly stronger effect on CTB than 9311. Total four quantitative trait loci (QTLs) for CTB were preliminary mapped on chromosomes 5 and 7 by substitution mapping. qCTB-5-1, qCTB-5-2 and qCTB-5-3 were mapped in the region of RM267-RM1237, RM2422-RM6054 and RM3321-RM1054, which were 21.3 cM, 27.4 cM and 12.7 cM in genetic distance on rice chromosome 5, respectively. qCTB-7 was mapped in a 6.8-cM region of RM11-RM2752 on rice chromosome 7. [Copyright &y& Elsevier]

Abstract: Rice with low glutelin content is suitable as functional food for patients affected by kidney failure. Low glutelin-content gene Lgc1 in rice has a 3.5-kb deletion between two highly similar glutelin genes GluB4 and GluB5, which locates on the short arm of chromosome 2. To improve the selection efficiency in low glutelin-content rice breeding, two molecular markers designated as InDel-Lgc1-1 and InDel-Lgc1-2 were developed to detect the low glutelin-content gene Lgc1. A double PCR detection indicated that combined use of the two markers could easily distinguish the genotypes of Lgc1 from different rice varieties. Therefore, as a simple and low-cost technique, the molecular marker could be widely used to identify different varieties with Lgc1 gene and applied in marker-assisted selection of low glutelin-content rice. [ABSTRACT FROM AUTHOR]

Abstract: The translucent endosperm trait in a japonica rice variety ‘Kantou 194’ is controlled by a Wx-mq gene which is allelic to Wx locus by genetic analysis and allelic test. The amylose content analysis showed that an intermediate amylose content between those of glutinous and non-glutinous rice existed in endosperm of homozygous Wx-mq genotype. The slight changes of amylose content in different varieties and F1 grains with an identical Wx-mq genotype might be influenced by dissimilar genetic background. To identify the Wx-mq genotype simply and rapidly, a cleaved amplified polymorphic sequence (CAPS) marker was designed. The result from the molecular detection indicated that it could be used for marker-assisted selection for low amylose content varieties in rice breeding. [Copyright &y& Elsevier]

Abstract: In order to improve the panicle extrusion of photo- and thermo-sensitive sterile line ‘Pei''ai 64S’ by using elongated uppermost internode (eui) gene of the wide compatibility rice mutant ‘02428h’, a new photo- and thermo-sensitive sterile line ‘P8hS’ characterized with elongated uppermost internode was developed by transferring the eui gene into Pei''ai 64S through three successive backcrossing. Compared with Pei''ai 64S, the plant height of P8hS was 35.6 cm higher resulted from the elongation of the uppermost and the second internodes from the top. The panicle extrusion of Pei''ai 64S was completely improved and positive effects were found on the main economic characters of P8hS and its hybrids by introducing eui gene into Pei''ai 64S. [Copyright &y& Elsevier]