The aroma of rice is associated with the presence of 2-acetyl-l-pyrroline (2-AP). According to the most scientists, the aromatic trait of rice is controlled by recessi ve genes and is not influenced of the cytoplasm. In the study, the authors used molecular markers associated with fragrant gene and sensory method to evaluate the fragrance of 50 quality rice varieties in Vietnam. The results based on sensory method showed that 43 rice varieties have a flavour from lightly scent to scent (points 1-2) and 7 unscented rice varieties (point 0). The results of molecular analyses showed that 33 rice varieties have recessive homologous BAD2 gene (The ratio is 66 percent), 9 varieties have dominant homozygous BAD2 gene (The ratio is 18 percent) and Saccessions have heterozygous BAD2 gene (The ratio is 16 percent). Most of traditional aromatic rice varieties (Tam rice varieties), specially aromatic rice varieties (Nang thom cho dao, specialty Nang thom, Thom lai, etc...) have fgr genotype and expressed the fragrance when smelling. Some varieties demonstrated heterozygous fragrant genotype, this proved that in the populations exist both dominant and recessive homozygous individuals (by automixis) and so that the expression of fragrance was different when evaluated by sensory methods. Four rice varieties have dominant homozygous genotype for BAD2 gene but also expressed fragrance (Tam trang Vinh Phuc, Khau tan pon, Nep cai nuong and Ne nuong)
this may due to a different mutantion allele in BAD2 locus, or the presence of another locus, that can control the fragrance.