Abstract: Five kinds of crosses (M×R, M×N, N×R, N×N and M×M，R, N and M representing resistant, necrotic and mosaic symptom, respectively) and their parents were used to study the inheritance of symptom reaction to soybean mosaic virus (SMV) in soybean. The results were as follows: (1) All plants of F1 from M×R crosses were symptomless. F2 populations segregated in a 3R: 1S ratio. The results showed that a single dominant gene controls resistance to SC8. (2) All F1 plants from M×N produced necrotic symptom, F2 population segregated in a 3N:1S ratio. It indicated that genes conditioning necrotic and mosaic symptom were at a same locus with necrosis being dominant to mosaic. (3) All F1 plants from N×R performed symptomless, F2 population segregated in a 3R : 1N ratio. It indicated that genes conditioning resistant and necrotic reaction are at a same locus with resistance being dominant to necrosis.（4）Non-segregation in N×N and M×M crosses showed that the genes for necrosis in different cultivars were at a same locus and the genes for mosaic symptom in different cultivars were also at a same locus. It was inferred that three types of symptoms of SMV in soybean were conditioned by a set of multiple alleles and the gene symbols SR, sN and sm were assigned for resistance, necrosis and mosaic symptom, respectively, with SR dominant to sN and sm and sN dominant to sm. Key words: Soybean mosaic virus (SMV); Symptom; Inheritance; Multiple alleles

Key words: Soybean mosaic virus (SMV), Symptom, Inheritance, Multiple alleles