Barley yellow dwarf virus(BYDV),vectored by several aphid species,is the most significant viral pathogen of wheat and other grain cereals.Significant economic losses resulting from BYDV in wheat,barley and oats have been reported in many countries.The most economic means of controlling BYDV is to develop wheat varieties with resistance to BYDV. So far no BYDV resistance has been described in wheat collections except one gene in some cultivars tolerant to BYDV. However, Thinopyrum intermedium ,two octoploids Zhong 4 awnless and TAF46,and the disomic addition lines,L1,Z1,Z2 and Z6 all showed resistance to BYDV. We developed several wheat Th.Intermedium translocation lines, Yw642, Yw443 and Yw243 etc., showing good BYDV resistance from L1 by inducing homologous pairing using CS Ph1 mutant. It was found that their BYDV resistance was controlled by a single dominant gene. Characterization of these wheat lines was carried out by GISH and RFLP analysis. The results of GISH showed that the lines, Yw642, Yw443 and Yw243 etc., were homozygous wheat Th.intermedium translocation lines containing 20 pairs of wheat chromosomes and 1 pair of wheat Th.intermedium translocation chromosomes,in which the chromosome segments of Th intermedium were transferred to the distal end of a pair of wheat chromosomes. RFLP analysis indicated that the translocation chromosome of the wheat lines was T7DS·7DL 7XL translocation. The breakpoint of translocation is located on the distal end of 7DL,between Xpsr965 and Xpsr680,about 90 99 cM from the centromere. The BYDV gene is located on the distal end of 7XL around Xpsr680,Xpsr687 and Xwg380.The RFLP markers of psr680,psr687 and wg380 co segregated with the BYDV resistance and could be used for marker assisted selection(MAS)in wheat breeding program for BYDV resistance.
