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Water availability is commonly the most limiting factor for crop production. This study was conducted to map wheat {Triticum aestivum L.) quantitative trait loci (QTL) involved in drought tolerance. Using amplified fragment length polymorphisms (AFLPs) and Diversity Array Technology (DArT) markers, a population of 122 F-,-derived recombinant inbred lines from a cross between 'Dharwar Dry' and 'Sitta' was reanalyzed to identify previously unknown QTL associated with drought tolerance traits and to further saturate known QTL regions. A linkage map of 48 groups was created from the combined data of DArT, AFLP, and previously reported simple sequence repeat (SSR) and expressed sequence tag (EST) markers. Quantitative trait loci were found in 24 of the 48 groups. Groups could be anchored on chromosomes ID, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6D, 7A, and 7B. While four additional AFLP markers were added to the major QTL for drought tolerance on chromosome 4AL, a second major locus was found on chromosome 7B. QDt.ksu-7B spans 34.7 cM with three associated markers. Simple sequence repeat marker Xbarc172 and DArT marker XwPt-4230 explained 11.9% of the variation for harvest index under reduced irrigation in 1999 while AFLP marker XGT'GG284 explained 10.7%, XwPt-6463 explained 11,9 and 11.2% of the variation for drought susceptibility index for spike number and yield, respectively. The locus QDt.ksu-4A now spans 21.9 oM and AFLP marker XCCGA110 explained 27.8 and 39.9% of the variation for grain fill rate and yield under reduced irrigation in 1999, respectively.

Lolium and Festuca are two important genera of cool-season forage and turf grasses worldwide. Lolium temulentum L. (darnel ryegrass) has been proposed as a model species for genomics studies of cool-season forage and turf grasses. A study with 41 darnel ryegrass, three tall fescue (Festuca arundinacea Schreb.), two tetraploid fescue (F. glaucescens), and two meadow fescue (F. pratensis) genotypes was initiated to (i) identify a set of microsatellite (simple sequence repeats) markers useful for L. temulentum L., and (ii) to utilize such markers for assessing the genetic variability of L. temulentum accessions collected from different geographical regions of the world. A total of 40 tall fescue (TF) EST-SSRs and 60 Festuca-Lolium (F · L) genomic SSRs were screened on a subset of eight genotypes. The selected 30 tall fescue ESTSSRs and 32 F · L genomic SSRs were used for further analysis of genotypes. The TF-EST-and the F · L genomic-SSRs identified 10.3 and 9.3 alleles per marker, respectively with an average polymorphic information content (PIC) value of 0.66. The phenogram based on 319 EST-SSR and 296 genomic SSR fragments, grouped L. temulentum accessions into three major clusters except for accession ABY-BA 8892.78. Lolium temulentum accession ABY-BA 8892.78 did not cluster with any other accession. The Festuca clusters were distantly related with darnel ryegrass clusters with a similarity coefficient of 0.26. The selected set of tall fescue EST-and F · L genomic SSRs were useful in assessing L. temulentum genetic diversity and could benefit the genetic improvement of members of the Festuca-Lolium complex.