VO~. 41 NO. 5 SCIENCE IN CHINA (Series C) October 1998 Breeding technology of alloplasmic wheat WU Yuwen (%%I!*), ZHAWG Cuilan ( ?& %% ) , LIU Chunguang (31 %% 1, REN Shuxin ( If #f ifi) and ZHANG Yan ( $# & ) (State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics, Chinese Academy of Sciences, Beijing 100101, China) Received September 12,1997; revised March 1, 1998 Abstract 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 re- sistance 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 characteris- tics 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 axtd was conse- quently pre-approved for large-scale plantation. The probing of the genetic variations and the utilition of alloplasmic wheat was proven to be valuable for both genetic study and breeding of new varieties. Keywords: wheat, cytoplasm effect, nucleoplasmic interaction, useful genetic variation, new alloplasmic variety. The nuclei of cultivated wheat could be transferred into cytoplasm of heterogenic species or genera via substitution backcross and other techniques, thus Triticinae exhibits wide genetic di- versity of cytoplasm. This diversity had both theoretic and breeding value and could be used in al- loplasmic wheat breedingL1'. Some of the basic issues regarding alloplasmic wheat have been reported, including wheat cy- toplasm genetics, origin and evolution of wheat and Aegilops, and molecular genetics of mito- chondria and chloroplast[2* 31 . Since ~ i h a r a ' ~ ] first proposed the possibility of applying nucleo- plasm hybrid heterosis in breeding, scientists have been paying attention to the introduction of al- loplasmic genes and the nucleo-cytoplasmic (NC) interaction as well as nuclear gene transfer[51. The new breeding technology with regard to alloplasmic wheat has been explored in our labo- ratory since 1978. More than 80 alloplasmic varieties or lines of common wheat, including 24 species with wild cytoplasm, were successfully bred. The genetic effects of wheat cytoplasm were pioneered through the comparison of major agronomic characteristics of homonucleo-heterocyto- plasm lines and homocytoplasm-heteronuclear lines. The characteristics and production potential of the new alloplasmic wheat varieties were demonstrated in large-scale production, which might provide a basis for further improvement of breeding technology regarding alloplasmic wheat. 1 Materials and methods 1.1 Materials 1.1.1 The alloplasrnic lines obtained in our laboratory The alloplasmic F1 was first