HIGH-RESOLUTION CYTOLOGICAL MAPPING OF THE LONG ARM OF CHROMOSOME 5A IN COMMON WHEAT USING A SERIES OF DELETION LINES INDUCED BY GAMETOCIDAL (GC) GENES OF AEGILOPS SPELTOIDES

Gametocidal (Gc) genes of Aegilops in the background of the wheat geno me lead to breakage of wheat chromosomes. The Q gene of wheat was used as a marker to select 19 deletion lines for the long arm of chromosom e 5A of common wheat, Triticum aestivum cv. Chinese Spring (CS). The e xtents of deleted segments were cytologically estimated by the C-bandi ng technique. The DNAs of deletion lines were hybridized with 22 DNA p robes recognizing sites on the long arm of the chromosome (5AL) to det ermine their physical order. Based on the breeding behavior of the del etion lines, the location of a novel gene (Pv, pollen viability) affec ting the viability of the male gamete was deduced. The segment translo cated from 4AL to 5AL in CS was cytologically estimated to represent 1 3% of the total length of 5AL. Although DNA markers were almost random ly distributed along the chromosome arm, DNA markers located around th e centromere and C-banded regions were obtained only rarely. Some dele tion lines were highly rearranged in chromosome structure due to the e ffect(s) of the Gc gene. Applications of Gc genes for manipulating whe at chromosomes are discussed.