Bread wheat is a major food crop on a global scale. Stripe rust, caused by Puccinia striiformis f. sp. tritici, has become one of the largest biotic stresses and limitations for wheat production in the 21st century. Post 2000 races of the pathogen are more virulent and able to overcome the defense of previously resistant cultivars. Despite the availability of effective fungicides, genetic resistance is the most economical, effective, and environmentally friendly way to control the disease. There are two major types of resistance to stripe rust: all-stage seedling resistance (ASR) and adult-plant resistance (APR). Although both resistance types have negative and positive attributes, ASR generally is race-specific and frequently is defeated by new races, while APR has been shown to be race non-specific and durable over time. Finding genes with high levels of APR has been a major goal for wheat improvement over the past few decades. Recent advancements in molecular mapping and sequencing technologies provide a valuable framework for the discovery and validation of new sources of resistance. Here we report the discovery of a precise molecular marker for a highly durable type of APR – high-temperature adult-plant (HTAP) resistance locus in the wheat cultivar Louise. Using a Louise × Penawawa mapping population, coupled with data from survey sequences of the wheat genome, linkage mapping, and synteny analysis techniques, we developed an amplified polymorphic sequence (CAPS) marker LPHTAP2B on the short arm of wheat chromosome 2B, which cosegregates with the resistant phenotype. LPHTAP2B accounted for 62 and 58% of phenotypic variance of disease severity and infection type data, respectively. Although cloning of the LPHTAP2B region is needed to further understand its role in durable resistance, this marker will greatly facilitate incorporation of the HTAP gene into new wheat cultivars with durable resistance to stripe rust.

Snap bean production in Kenya is constrained by many pests and diseases, including the bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV). The occurrence of the dominant I gene in many snap bean cultivars has provided a measure of control over BCMV but the BCMNV overcomes this resistance. The current study aimed to screen a collection of locally grown snap bean commercial cultivars, landraces, breeding lines, and dry bean cultivars for the expression of resistance against BCMNV under both field and greenhouse conditions. The results showed that the evaluated snap bean cultivars were susceptible to BCMNV. The reactions of the genotypes to BCMNV varied from top, vein and local necrosis, mosaics, mottling, deformed leaves to stunted growth. Positive infection was confirmed through enzyme linked immunosorbent assays. The dry bean cultivars, which were used as resistant checks can be explored as sources of resistance to BCMNV in future breeding programs. Molecular analysis showed that the SW13 and elF4E markers were reliable in confirming the presence or absence of the dominant I gene and the recessive bc-3 gene, respectively. These molecular markers are useful in markerassisted breeding programs.