抄録
Among a number of crosses between rice varieties, lethality of F1 plants was found in two crosses. It was shown that this hybrid inviability was due to a set of “complementary dominant lethals”.
It is generally found that when distantly related varieties of rice are crossed, a few F2 plants show a poor growth. In a cross showing this phenomenon typically, the underlying genes were analyzed. It was found that a set of duplicate genes, A1-a1 and a2-A2, are concerned, and that possessing two A's, i.e. A1A1, A2A2 or A1A2, is necessary for normal growth. These genes may be said as “complementary recessive lethals”. since the recessive alleles, if combined, produce a lethal effect. It was discussed that this type of duplicate genes may be widely spread among rice varieties, and may work as an isolating barrier between distantly related varieties.
