Study on the Utilization of Aphid Resistant Character in Wild Soybean. I. Aphid Resistant Performance of F2 Generation from Crosses Between Cultivated and Wild Soybeans

摘要

Three crosses between 3 cultivat ed (G. max) and 2 aphid resistant wild soybean (G. soja) lines were made to study the inheritance of resistance and segregation patterns in F 2 generation with artificial inoculation technique s. The aphid resistance of F2 plants showed continuous mono-peek distributions which are inclined towards the susceptible parents. Most F2 plants were susceptible or highly susceptible. Only about 7.2 to 10.2% of the F2 plants were resistant to soybean aphid. The segregations in 2 out of 3 crosses studied fitted the hyp othesis that there are 2 independent gene pairs controlling the aphid resistant character of the wild soybean lines (P > 0.50). The segregation of the other cross also tended to fit the 2 major gene model. These results indicated that the aphid resistance of the wild parents might be controlled by 2 independent recessive genes and some other minor genes. Supposing that the aphid resistant character was quantitatively inherited, the overall inheritability estimated from the variances of parents and F 2 populations was between 85.5% and 97.0%. Despite of the high inheritability of aphid resistance, it is recommended that the selection of resistance should be postponed to later generations such as F3 or F4 , because the scarcity of resistant genes may be recessively inherited, and the number of backcrosses made in each cycle of selection should be limited to avoid the resistant genes being lost.