Alloplasmic wheat:genetic variations and utilization in wheat breeding
Over the past few years we have evaluated a number of homonucleo-heterocytoplasmic and homocytoplasm-heteronuclear alloplasmic wheats in terms of their grain protein content and resistance to environmental stress. We found that the cytoplasms from several Aegilops species, namely, Ae. crassa, Ae. squarrosa and Ae. ventricosa, were able to produce useful genetic effects on grain quality, salt tolerance and resistance to the scab disease in alloplasmic wheats. The degree of this nucleoplasmic (NC-) heterosis varied in different types of alloplasmic materials. This indicates that a careful exploitation of the genetic variation caused by alloplasm may be a useful strategy to breed wheat varieties with improved grain quality, high resistance to environmental stress and hence good yield potential. Based on above study, a new spring wheat variety bearing the cytoplam of Ae. crassa, iaoshan 2134? and a few new strains (spring-type or winter-type) with the cytoplam of Ae. crassa was bred. Field trials of over a period of 2-8 years showed that the yields of xiaoshan 2134?xiaoshan 2, xiaoshan 230, xiaoshan 221 et al were 5.0-24.0% higher than that of the euplasm control variety. These results suggest that alloplasms have potential for broadening the genetic base of wheat and for utilizing NC-heterosis.