| 'Green revolution'which was charactered by dwarf breeding has promoted the crop yield greatly since 1960's. Dwarf sources used in indica breeding were almost controlled by the same gene sd1. Narrow dwarf sources have limited rice yielding seriously. Besides, cloning of new dwarf genes will make great sense to research into the law of plant development.In this study, a natural dwarf rice mutant was found and named sde(t), and it has several favorable agronomic traits such as dwarfing, bottle-green leaf, etc. Comparing to the wild type, all internodes of sde(t) were shortened, but the proportion of each internode to plant height remained unchanged. Anatomic analysis revealed that cells of the second internode in sde(t) were much shorter than those in wild type, and hence dwarfing. Agar plate assay showed that sde(t) may be a GA deficient rice mutant.For genetic analysis of the sde(t), F2 populations were generated from the cross between the sde(t) and Zhonghua 11. Plant height of F1 populations were normal, however F2 plants segregated into two groups showing wild type and dwarf phenotype in 3:1 ratio, which implied that the mutant phenotype was controlled by a single recessive nuclear gene.We developed pairs of new STS and CAPS markers and mapped sde(t) by map-based cloning strategy. By using 22 dwarf F2 plants and 38 polymorphic markers sde(t) was mapped on the rice chromosome 1 firstly. With the other 138 F2 dwarf plants, the sde(t) gene was then mapped on the long arm of chromosome 1 between two STS markers, and the physical gap of them is about 400kb.This made a solid basis for our future work.
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