We made interspecific crosses to facilitate the introgression of desirable traits of Allium roylei into the Alliumcepa genome. After hand-pollination, 906 interspecific F1Allium cepa × A. roylei plants were obtained by in vitro culture via embryo rescue. Nuclear DNA analysis showed that 97.6% of the regenerants were interspecific F1Allium cepa × A. roylei hybrids. Genomic in situ hybridization (GISH) showed that each hybrid had 16 chromosomes, eight of which were identified as A. cepa and eight as A. roylei chromosomes.

Isozyme, RAPD and AFLP markers were evaluated and compared for their ability to determine genetic similarity in a set of 18 parental lines of winter oilseed rape F₁ hybrids developed using CMS ogura. Five isozyme systems, 64 RAPD starters and 23 EcoRI+3/MseI+3 AFLP primer combinations generated 597 polymorphic markers. These polymorphic fragments were chosen for estimation of genetic similarity. Of the total number of polymorphic products, polymorphic zymograms constituted only 3.0% of the markers, 57 RAPD primers 37.7%, and 23 AFLP primer combinations 59.3%. The size of RAPD polymorphic products ranged from 564 to 2100 bp. On average there were four amplified bands per primer, with 61.0% polymorphism. The AFLP polymorphic fragments ranged from 72 to 1352 bp in size. AFLP assays generated 15 bands per primer pair on average and detected roughly four times more bands than with RAPD analysis. The genetic similarity coefficients based on all marker data range from 0.52 to 0.84. The correlation of genetic similarities based on RAPD and AFLP markers was 0.58. Estimated genetic similarity based on isozyme data was not correlated with genetic similarity derived from the two DNA-based markers. The dendrogram constructed with the three types of markers taken together grouped all the winter oilseed rape parental lines into several similar clusters. The genomic distribution and frequency of the RAPD and AFLP markers can serve well as estimators of genetic similarity between parental lines of F₁ CMS ogura hybrids

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.