Breeding technology of alloplasmic wheat.

Novel wheat bearing alloplasm was bred via nucleo substitution backcross. Through comparative study between the hornonucleo-heterocytoplasmic lines and homocytoplasm-heteronuclear lines, it was shown that a portion of the alloplasm types were able to produce useful genetic effects on wheat yield, grain quality, tolerance of salt and resistance to diseases. Among the species studied, the cytoplasm of Aegilops crassa, Ae. squarrosa and Ae. vcntricosa contributed the best effect. Specific combination of nuclear genes and cytoplasmic genes conferred specific characteristics and degree of nucleoplasmic heterosis. The alloplasmic wheat lines with cytoplasm substituted were successfully bred with good quality and resistance to disease and harsh conditions. In particular, the new variety of nucleoplasmic hybrid having Ae. crassa cytoplasm proved the best in production test, demonstration and regional test and was consequently pre-approved for large-scale plantation. The probing of the genetic variations and the utilization of alloplasmic wheat was proven to be valuable for both genetic study and breeding of new varieties.