White mold, caused by the fungus Sclerotinia sclerotiorum (Lib.) de Bary, is a major disease that limits common bean production and quality worldwide. The host-pathogen interaction is complex, with partial resistance in the host inherited as a quantitative trait with low to moderate heritability. Our objective was to identify meta-QTL conditioning partial resistance to white mold from individual QTL identified across multiple populations and environments. The physical positions for 37 individual QTL were identified across 14 recombinant inbred bi-parental populations (six new, three re-genotyped, and five from the literature). A meta-QTL analysis of the 37 QTL was conducted using the genetic linkage map of Stampede x Red Hawk population as the reference. The 37 QTL condensed into 17 named loci (12 previously named and five new) of which nine were defined as meta-QTL WM1.1, WM2.2, WM3.1, WM5.4, WM6.2, WM7.1, WM7.4, WM7.5, and WM8.3. The nine meta-QTL had confidence intervals ranging from 0.65 to 9.41 Mb. Candidate genes shown to express under S. sclerotiorum infection in other studies, including cell wall receptor kinase, COI1, ethylene responsive transcription factor, peroxidase, and MYB transcription factor, were found within the confidence interval for five of the meta-QTL. The nine meta-QTL are recommended as potential targets for MAS for partial resistance to white mold in common bean.

Two hundred forty-six snap bean genotypes and 49 dry beans representing both centers of domestication and six bean races with materials from Europe, Asia, and the Americas were genotyped using a single nucleotide polymorphism (SNP) array. The data was analyzed for expected heterozygosity, K-means clustering, principal components, phylogenetic relationships, and population substructure. When all gene pools of snap bean were assembled, the expected heterozygosity was roughly equivalent to a carefully chosen panel of dry beans representing all bean races and centers of domestication demonstrating the genetic richness of snap materials in total. K-means clustering and K = 2 structure analysis showed significant mixing of gene pools in the European and American commercial snap materials and the dominance of the Andean center of domestication among commercial contemporary snap beans. Conversely, the same analysis showed that Chinese, Iberian, and heirloom materials were underrepresented in contemporary materials. Further, Structure analysis revealed eight distinct groups within snap beans. Two showed strong kinship to the Middle American center of domestication, three to the Andean center of domestication, and three showed admixture between the two centers. Snap beans may have been independently derived from dry beans more than once and from both centers. Overall, we identified eight potential germplasm pools for snap bean.

White mold can result in snap bean yield losses of 90 to 100% when field conditions favor the pathogen. A genome-wide association study (GWAS) was conducted to detect loci significantly associated with white mold resistance in a panel of snap bean (Phaseolus vulgaris L.) cultivars. Two populations of snap bean were used in this study. The first population was the BeanCAP (Coordinated Agriculture Project) Snap Bean Diversity Panel (SBDP) (n = 136), and the second population was the Snap Bean Association Panel (SnAP) (n = 378). SBDP was evaluated for white mold reaction in the field in 2012 and 2013, and SnAP was screened in a greenhouse only using the seedling straw test in 2016. Two reference genomes representing the Andean and Middle American centers of domestication were utilized to align the genotyping-by-sequencing (GBS) data. A GWAS was performed using FarmCPU with one principal component after comparing five models. Thirty-four single-nucleotide polymorphisms (SNPs) significantly associated with white mold resistance were detected. Eleven significant SNPs were identified by the seedling straw test, and 23 significant SNPs were identified by field data. Fifteen SNPs were identified within a 100 kb window containing pentatricopeptide repeat (PPR)-encoding genes, and eleven were close to leucine-rich repeat (LRR)-encoding genes, suggesting that these two classes are of outsized importance for snap bean resistance to white mold.

Reciprocal hybrids are achieved by crossing parental genotypes in both directions, while heterosis happens when the F1s surpass their parental lines for a characteristic. Two different tomatoes (Solanum lycopersicum L.) cultivars were crossed reciprocally to study the impact of the reciprocal cross and heterosis phenomenon on numerous tomato characteristics. Fifty-two different traits were measured, including flower, fruit, leaf, shoot, roots, yield and yield components, and physiochemical traits. The results showed that various traits were significantly influenced by reciprocal crosses, such as plant mass, petal length, cone length, pistil length, fruit width, fruit length, single fruit weight, fruit flesh weight, seed and placenta weight, number of fruits locules, fruit calyx weight, number of days to flower, total sugar, ascorbic acid, anthocyanin, and total phenolic content. In addition, the results showed that several traits showed positive high parent heterosis, which are the sepal length, pistil length, flower fresh weight, flower dry weight, flower moisture content, number of clusters per plant, number of flowers per plant, number of flowers per cluster, number of fruits per cluster, fruits number per plant, total fruits weight per plant, leaf length, leaf fresh weight, leaf dry weight, number of branches per plant, plant height, plant mass, ascorbic acid, total carotene, and anthocyanin. These results will be significantly helpful for the future breeding program, especially for breeding for yield and yield components that showed strong heterosis for most of the traits.

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