The Molecular Basis of Rice Fragrance in the High Quality Japonica Hybrid Rice Variety Dianheyou34

PurposesIt is important to clarifying the molecular mechanism of the aroma in hybrid rice for selecting new varieties with this high value trait, a japonica hybrid rice variety Dianheyou34 with aromatic character was used to study the aromatic genetic pattern in hybrid rice.

MethodsThe betaine aldehyde dehydrogenase gene, OsBADH2 which is the main factor control the fragrance in rice were cloned in the two parents of japonica hybrid rice Dianheyou34, the cytoplasmic male sterile (CMS) line H479A and the restorer line Nan34; the aroma of the leave from the F₂ population which came from Dianheyou34 was checked by KOH soaked method, and the genotype of all plants were identified by a Osbadh2-E7 alleles specific molecular marks.

ResultsThe OsBADH2 of Nan34 was a wild type allele which could express an intact functional betaine aldehyde dehydrogenase, in contrast the allele in the CMS line H479A was a typical mutational one, Osbadh2-E7 which exits in most aromatic germplasm, expressed a loss of functional protein. The results of the phenotypic identification in the F₂ population showed that there were 31.8% of plants be aromatic, χ² test showed that segregation ratio between aromatic and no-aromatic plants accord with the one pair genes controlled rule, 3:1, and the aromatic trait was recessive. Based on the results of the genotype, besides the pure mutation plants, there were 23.1% of total heterozygous plants be aromatic.

ConclusionBecause of the mutational allele Osbadh2-E7 in the CMS line H479A, there were a quarter pure mutational genotype grains in the F₂ population which yield in the Dianheyou34 production fields production, that led the cooked rice with fragrance. Except for this, there were also parts of heterozygous grains could produce aroma, but the mechanism needs more research.