The 4E‐ ms System of Producing Hybrid Wheat

A cytogenetic method for producing hybrid seed using a nuclear gene for male sterility and an alien chromosome to obtain a pollination control system has been proposed in bread wheat ( Triticum aestivum L.). Our objective was to transfer the alien chromosome 4E to the monogenic recessive male‐sterile mutant Lanzhou (LZ), and then to establish an efficient cytogenetic system of maintaining the male sterility of the LZ mutant. After crossing the 4E disomic addition line 81529 (2 n = 44) as male to LZ [2 n = 42( msms ) = 42], we obtained the 4E monosomic addition line [2 n = 43( msms )] in the F 3 generation that had light‐blue seed color. The line was homozygous for the male‐sterile gene ( msms ) of the host wheat and also had good self‐fertility. The self‐fertilized seeds segregated into 64.3% white (nonblue) with genotype 2 n = 42 (msms) , 32.1% light blue with genotype 2 n = 43 (msms) and 3.6% deep blue with genotype 2 n = 44 (msms) grains. All plants grown from the white grains were completely male sterile. All plants grown from the light‐blue grains had good self‐fertility whose progeny seeds segregated into white, light‐blue, and deep‐blue grains again in succeeding generations. All plants grown from the deep‐blue grains were self‐fertile and retained their deep‐blue color in the succeeding generations. When white grain male‐sterile lines were crossed using any cultivar as the male parent, the hybrid plants had male fertility restored. And, this is the basis for the 4E‐ ms system of producing hybrid wheat.