A Proposal for Hybrid Wheat Utilizing Aegilops squarrosa L. Cytoplasm1

The nucleocytoplasmlc interactions of Aegiiops squatrosa L. (2n=14,DD) cytoplasm and Triticum durum Desf. (2n=28;AABB) or T. aestivum L. em Thell. (2n=42,AABBDD) nuclei indicate that a new cytoplasmic male sterility‐male fertility restoration system can be developed for hybrid wheat production. The proposed system should be more efficient than those cytoplasmic male‐sterility systems that require breeding of R‐lines to produce fertile hybrids, because conventional wheat cultivars can be used as R‐lines in the new system. The D genome of common wheat contains genetic factor(s) for restoration of fertility of T. aestivum with A. squarrosa cytoplasm, and induced mutations may inactivate these critical gene(s). Therefore, seed of alloplasmic T. aestirum with A. squarrosa cytoplasm was treated with ethyl methanesulfonate (EMS). Nine male‐sterile mutants were selected and crossed with common wheats. Most mutants had monogenic or digenic inheritance for male sterility and produced normal F1 and F2 hybrids. The male‐sterile mutants can be used to develop male‐sterile A‐lines and maintainer B‐lines for the production of hybrid wheat if the sterility genes are specific for A. squarrosa cytoplasm.