Fertility restoration for Triticum timopheevi Zhuk, cytoplasmic male steriligy in wheat (Triticum aestivum L.) is controlled by both major fertility restorer (Rf) grnes and modifier genes together with environ-ment efiects. Therefore, the breeding of efficient and stable male-fertility restorer lines (R-lines) should be facilitated by marker-assisted selection. This study was conducted to ldentify restriction fragment length polymorphism (RFLP) markers for the Rf genes, Rf1 and Rf4 in restorer line R113, and Rf3 and a Rf gene on 5D in cultivar Primepi, Polymorphic markers were mapped in testcross F1 populations and their association with fertility restoration was analyzed by analysis of variance. The results Indicated that Rf4 was linked to Xksug48 located on 6BS in R113, Rf3 was linked to Xbed249 and Xcdo442 on 1BS, and Xcdo786 may be associated with the 5D Rf gene in Primepi. In addition, in R113 two other chromosome regions with fertility restoration-associated loci were detected by CD0786 and H1 on 5AL and CD-O1189 on 7BS. A locus on 5DS, detected by BCD1871, showed significant epistatic effect on the expression of Rf genes. InPrimepi, a locus on 5AL, detected by Xbcd183 and Xbcd876, had effects similar to Xcdo786. Two loci in Qu Xian Early A', identified by Xbcd871 and Xwg1026, may be associated with genes controlling ease of restoration in this male-sterile line (A-line). Except for Xbcd1871 and Xwg1026, the effects of other significant RFLP loci were additive in both populations.

Microsatetlites have emerged as an important source of genetic markers for eukaryotic genomes. In this report, two wheat (Triticum aestivurn L.) genomic libraries were screened for several di-. tri-. and tetra-nucleotide tandem repeats. Clones containing (AC)n, (AG)n. (TCT)n. and (TTG), repeats were isolated and sequenced. On average, there was one (AC)n microsatellite every 292 kbp and one (AG) microsatellite every 212 kbp. The trinucleotide tatdern repeats (TCT) and ('I'rG) were about 10 times less common than the two dinucleotide tandem repeats tested and tetranueleotide tandem repeats were rare. Many of the microsate[lites had more than 10 repeats. The maximum repeat number found for (AC), was 36 and for (TCT)n was more than 50. The prevailing category of (AG) microsatel|ites from (AG), isolates was perfect repeats. About half of the (AC), microsatellites were compound repeats, while most of the (TCT). microsatellites were imperfect repeats. In a small sample. (TTG), microsatellites consisted mainly of compound repeats. The most frequently associated repeats were (AC)n with (AG)n. (TCT), with (TCC),. and (TTG), with (TGG)n. Among 32 pairs of microsatellite primers surveyed, seven.produced polymorphic products in the expected size range and theze loci were mapped using a hexaploid wheat mapping population or aneuploid stocks.

The amplified fragment length polymorphism (AFLP) technique was assessed for its effectiveness as a marker system in wheat, a hexaploid specles with a large genome (1.6x1010 bp per haploid). The degree of polymorphism detected by AFLP among 11 pure lines of wheat was determined and compared with the polymorphism detected by RFLP. Cost comparison between AFLP and RFLP techniques was also made. The appropriate amount of wheat genomicDNA as template in pre-amplification was first determined. All 20 AFLP primer pairs tested resulted in amplification of bands which were polymorphic between all pairwise genotype comparisons. On average, 106 products per genotype were amplified, and for each primer pair used, more than 25 polymorphic fragments detected polymorphism among the 11 genotypes. In comparison, only 61% of 18 RFLP probes tested detected polymorphism among 10 of the 11 lines and each polymorphic probe detected an average of only three bands showing polymorphism between genotype pairs. The AFLP technique is more efficient but less expensive and requires less labor than the R.P technique in wheat.

Near-isogenic lines (NILs) and their recurrent parent Chancellor (Co) were used to identify restriction fragment length polymorphic markers linked to powdery mildew (Blumeria graminis (DC.) E.O. Speer f.sp. tritici) resistance genes Pm], Pro2, Pro3, and Pro4 in wheat (Triticum aestivum L. em. Theli). By mapping these poIymorphic markers in F: progenies from crosses of the NILs with C, it was found that Pro1 cosegregated with a polymovphic locus detected by DNA probe CDO347; Pro2 was linked to a locus detected by probe B CD[871 with a distance of 35 cM; Pm3b was linked to a locus detected by probe BCD1434 with a distance of 1.3 cM; Pm4a cosegregated with Xbcd1231-2A(2) and Xcdod78-2A, and was closeIy flanked by Xbcd1231-2A(t) and Xbcd292-2A both wiEh a distance of 1.5 cM. Aneuploid mapping of these markers indicated that locus Xcdo347-TA is on 7AL, Xbcd187]-5D on 5DS, Xbcd1434-1A on IAS, and loci Xbcd292-2A and Xcdo678-2A are on 2AL. The same polymorphic fragments detected in the Pm3b NIL by Xbcd1434-1A were found in Pm2a NIL. using several enzyme digestions.