Abstract:

Utilization of dwarf and semi-dwarf genes was one of the greatest achievements in rice breeding in 20^th century. Through ion beam mutagenesis, a new rice semi-dwarf mutant Y98149 was obtained. The plant height of Y98149 was controlled by a pair of dominant genes, not affected by cytoplasm. This dominant semi-dwarf gene could be used to resolve the problem of the dwarf gene deficient in rice dwarf breeding and the heterobeltiosis of F₁ in plant height in the utilization of inter-subspecific heterosis. Y98148 and Y98149 are near-isogenic lines(NILs) of dominant semi-dwarf gene. A RAPD analysis was made between NILs with arbitrary 10-mer oligonucleotide primers and three polymorphic RAPD bands were obtained. The three special RAPD bands were recovered ,purified and inserted in pUCm-T vector, and then transferred into E.coli. JM109. Positive colonies were identified for sequencing(Fig.1). According to the obtained sequences, 18–24-mer specific primers were designed as SCAR primers, and the SCAR-PCR reaction conditions were optimized. Consequently, RAPD markers S1041₅₂₅, S1076₅₄₉ and S1272₄₀₃ were successfully converted into SCAR markers SCS1041₄₉₈, SCS1076₅₁₀ and SCS1272₃₈₈, most optimal annealing temperature were 61℃,58℃ and 62℃,respectively. F₂ progeny with 384 individuals of Y98148×Y98149 was analyzed to map SCAR markers in relationship to this gene. The result indicated that the genetic distances of SCS1041₄₉₈, SCS1076₅₁₀ and SCS1272₃₈₈ to the gene were 12.6 cM, 7.5 cM and 16.3 cM, respectively. The blast result indicated nucleotide sequence of marker S1272₄₀₃ was 99% identical with the BAC clones B1249D05（AP006451）and OJ1212_C12（AP005604）on chromosome 7 and was a single copy in rice genomic DNA. B1249D05 and OJ1212_C12 had a overlap of 23 kb, which marker S1272₄₀₃ lay in. So this new semi-dwarf gene was considered to be located on chromosome 7 preliminarily. The markers are useful to marker-assisted selection for the breeding and tagging it with positional cloning.

Key words: Rice, Semi-dwarf mutant, Dominant gene, SCAR, Gene location