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Bruchids are a major storage pest of common bean. Genetic resistance is a suitable method to avoid grain losses during storage. The objective of the study was to introgress the arcelin-based resistance locus into selected advanced breeding line and to validate the molecular marker BRU_00261. A total of 208 progeny F 4 families were phenotyped using a randomized complete block design, with three replications. Highly significant differences (P < .001) among the entries, parents and offspring were recorded for almost all traits. There was no significant difference between the two parents in the number of eggs laid. The progenies were grouped as highly resistant (34.3%), resistant (11.9%), moderately resistant (21.4%) and susceptible (32.4%).The levels of broad sense heritability ranged from 68.5%-93.9% for all the traits. Eighty-three most resistant lines and the parental lines were genotyped with the marker BRU_00261 (snpPV0007). The marker segregation deviated significantly from the expected independent segregation towards a strong enrichment for the resistant marker in the selected families. This marker will be useful for selecting promising materials in early generations and phenotypic confirmation of positive lines in later generations.

The aims of the study were to determine expected genetic gains from selection and the extent and pattern of genetic diversity of common bean genotypes to Mexican bean weevil. Three hundred bean genotypes were artificially infested with the Mexican bean weevil. The experiment was laid out in a randomized complete block design with three replications. Data on thirteen insect and seed related traits were recorded and subjected to statistical analysis. The broad-sense heritability values ranged from 68.5%–93.9% for the traits studied. The expected genetic gains from selection ranged from 5.9%-67.1% for insect related traits and from 0.2%-82.2% for seed related traits. Seed weight loss showed significant positive phenotypic and genotypic correlation with number of eggs, number of adults emerged, percent adult emergence, index of susceptibility, number of holes and first and second progeny damage. Cluster analysis classified the 300 genotypes into two major clusters and seven sub-clusters. Mahalanobis’s D2 value calculated among the sub clusters ranged from 5.6 to 191.6. There was no defined relationship between geographic origins and the pattern of genetic diversity in response to Mexican been weevil infestation. Therefore, parental selection should be made based on genetic diversity and other special merits of the genotype for the resistance attributes. The introgression of the resistance gene into the adapted improved varieties and landraces, and increasing the frequency of resistance genes through selection could be used as a strategy to improve bruchid resistance in the future

Background: The most commonly used method for extracting DNA from plant leaf tissue involves cetyl trimethylammonium bromide but some species, such as Acacia mearnsii, contain high levels of secondary metabolites and polysaccharides that interfere with this process. Various modifications have been proposed for effective removal of these biomolecules but these methods can be time consuming. Therefore, this study was initiated to optimise the cetyl-trimethylammonium bromide protocol for the extraction of high-quality genomic DNA and to develop a fingerprinting tool using cross species transferable simple sequence repeat markers for genetic diversity studies in A. mearnsii. Methods: Five CTAB-based modification were examined and 49 cross-species microsatellite markers, developed for several Acacia species, were tested in four multiplex panels of A. mearnsii populations. Results: The modified protocol yields high quantity and quality DNA from A. mearnsii leaves using high concentration of NaCl to remove polysaccharides and polyvinylpolypyrrolidone (PVPP) to eliminate polyphenols during DNA purification. In addition, omitting the selective precipitation and NaCl gradient steps in the extraction protocol, enabled us to extract DNA 10–20 min faster than the normal protocol. Of the tested microsatellite loci, 11 were successful in amplifying sharp and high-intensity bands in all the four multiplex panels and were polymorphic. The level of polymorphism ranged from 0.115 to 0.794, with a mean 0.50 and mean number of alleles varied from 2 to 10, with overall mean of 6 alleles per locus. The mean observed and expected heterozygosity ranged from 0.058 to 0.970 and 0.102 to 0.796, respectively. The 11 microsatellite loci that were effectively amplified from A. mearnsii DNA were adequate in detecting genetic variation among the tested populations. Conclusions: These PCR-based, multi-allelic, co-dominant microsatellite markers provide a powerful tool for genetic, breeding and conservation studies in A. mearnsii.