A dwarf mutant of rice （Oryza sativa L.） by mutagenesis of ethylene methylsulfonate （EMS） treatment from Nipponbare was identified. The mutant exhibited phenotypes of dwarfism and withered leaf tip （dwll）. Based on the intemode length of dwll, this mutant belongs to the dm type of dwarfing. Analysis of elongation of the second sheath and m-amylase activity in endosperm showed that the phenotype caused by dwll was insensitive to gibberellin acid treatment. Using a large F2 population derived from a cross between the dwll and an indica rice variety, TN1, the DWL1 gene was mapped to the terminal region of the long arm of chromosome 3. Fine-mapping delimited it into a 46 kb physical distance between two STS markers, HL921 and HL944, where 6 open reading frames were predicted. Cloning of DWL1 will contribute to dissecting molecular mechanism that regulates plant height in rice, which will be beneficial to molecular assisted selection of this important trait.
The exploration of new genes controlling rice leaf shape is an important foundation for rice functional genomics and plant architecture improvement. In the present study, we identified a rolling leaf mutant from indica variety Yuefeng B, named rl11(t), which exhibited reduced plant height, rolling and narrow leaves. Leaves in rl11(t) mutant showed abnormal number and morphology of veins compared with those in wild type plants. In addition, rl11(t) mutant was less sensitive to the inhibitory effect of auxin than the wild type. Genetic analysis suggested that the mutant was controlled by a single recessive gene. Gene Rl11(t) was initially mapped between SSR markers RM6089 and RM124 on chromosome 4. Thirty-two new STS markers around the Rl11(t) region were developed for fine mapping. A physical map encompassing the Rl11(t) locus was constructed and the target gene was finally delimited to a 31.6 kb window between STS4-25 and STS4-26 on BAC AL606645. This provides useful information for cloning of Rl11(t) gene.
Rice grain shape is one of the important factors affecting grain quality and yield,but it is liable to be influenced by genetic backgrounds and environments.The chromosome single segment substitution lines(SSSLs) in rice have been considered as ideal populations to identify the quantitative trait loci(QTLs).In this study,22 QTLs affecting rice grain shape were detected to be distributed on eight chromosomes except chromosomes 6,9,11 and 12 by using SSSLs.Among them,seven QTLs conditioned grain length,six conditioned grain width,five affected grain length-width ratio and four controlled grain thickness.
