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Barley stripe or yellowrust (BYR) caused by Puccinia striiformis f. sp. hordei (Psh) is a significant constraint to barley production. The disease is best controlled by genetic resistance, which is considered the most economical and sustainable component of integrated disease management. In this study, we assessed the diversity of resistance to Psh in a panel of international barley genotypes (n = 266) under multiple disease environments (Ecuador, India, and Mexico) using genome-wide association studies (GWASs). Four quantitative trait loci (QTLs) (three on chromosome 1H and one on 7H) associated with resistance to Psh were identified. The QTLs were validated by mapping resistance to Psh in five biparental populations, which detected key genomic regions on chromosomes 1H (populations Pompadour/Zhoungdamei, Pompadour/Zug161, and CI9214/Baudin), 3H (Ricardo/Gus), and 7H (Fumai8/Baronesse). The QTL RpshQ.GWA.1H.1 detected by GWAS and RpshQ.Bau.1H detected using biparental mapping populations co-located were the most consistent and stable across environments and are likely the same resistance region. RpshQ.Bau.1H was saturated using population CI9214/Baudin by enriching the target region, which placed the resistance locus between 7.9 and 8.1 Mbp (flanked by markers sun_B1H_03, 0.7 cM proximal to Rpsh_1H and sun_B1H_KASP_02, 3.2 cM distal on 1HS) in the Morex reference genome v.2. A Kompetitive Allele Specific PCR (KASP) marker sun_B1H_KASP_01 that cosegregated for RpshQ.Bau.1H was developed. The marker was validated on 50 Australian barley cultivars, showingwell-defined allelic discrimination and presence in six genotypes (Baudin, Fathom, Flagship, Grout, Sakurastar, and Shepherd). This marker can be used for reliable marker-assisted selection and pyramiding of resistance to Psh and in diversifying the genetic base of resistance to stripe rust. [ABSTRACT FROM AUTHOR]

High temperature stress affects tomato production both in tropical and sub-tropical environments worldwide. To explore genetic variation for heat tolerance in tomato, 329 transcontinental tomato genotypes were evaluated at the Ministry of Municipality and Environment (MME) greenhouses near Doha, Qatar, where the average daytime temperature was 38 °C with a big fluctuation during the tomato growth season. A preliminary phenotypic analysis identified a panel of 71 hybrid and pure-line tomato genotypes for more detailed studies. The selected subset was examined in the greenhouse using a randomized complete block design under heat stress. The materials were phenotyped for fruit size, fruit weight, fruit hardness, fruit locules, fruit set, total soluble solids (TSS), and fruit yield. Significant phenotypic differences among genotypes were observed for all the traits assessed. To explore the genetic basis of the variation among the examined genotypes, the subset was genotyped using 104 SNP markers identified in previous heat-tolerance genome-wide association studies (GWAS). Nineteen QTL-associated SNP markers could reliably select heat-tolerant genotypes in terms of better fruit yield, fruit set, and TSS. These markers are located on chromosome 1, 5, 6, 8, 9, and 12. Interestingly, two clusters of markers on chromosome 6 were linked to significant effects on yield, fruit set, and TSS under high temperature. Eighteen out of nineteen SNP markers were mapped within a gene body. Based on the phenotypic and the genotypic analysis, an elite set of five genotypes was selected for approval for heat stress environments in Qatar. The aim of the present work is to provide significant results that are exploitable not only in the Qatar region but also worldwide. Specifically, the 19 molecular markers identified in this study can serve as useful tools for breeders in selecting heat-tolerant material. [ABSTRACT FROM AUTHOR]