Molecular diversity of Pakistani mango (Mangifera indica L.) varieties based on microsatellite markers.

Understanding the genetic diversity of different Pakistani mango varieties is important for germplasm management and varietal characterization. Microsatellites are efficient and highly polymorphic markers for comparative genome mapping, and were used in the present study to determine the genetic relatedness and variability among 15 indigenous mango cultivars (Mangifera indica L.). Overall, 181 bands were produced using 12 simple sequence repeat (SSR) primers. Out of the 12 primers used, 10 were polymorphic and two were monomorphic. Genetic relatedness among cultivars was assessed by constructing a dendrogram using the unweighted pair group method of arithmetic means. The accessions exhibited coefficients of similarity ranging from 75 to 100%, indicating the frequent use of only a few parent cultivars and the presence of inbreeding. The primers used in the present study were found to be valuable for identifying genetic relationships among mango cultivars.

Assessment of genetic diversity of cotton genotypes for various economic traits against cotton leaf curl disease (CLCuD).

In Pakistan, cotton crop has been under enormous threat of cotton leaf curl disease (CLCuD) over the last four decades. In order to estimate genetic diversity in cotton germplasm CLCuD resistance, we assessed 100 cotton genotypes for their CLCuD resistance/tolerance and other related agronomical traits. Various statistical analytical tools, including correlation analysis, cluster analysis, and principal component analysis (PCA), were used to select the best genotypes. These genotypes can be used in future breeding programs to generate CLCuD resistant varieties. The same set of procedures could be utilized for other diseases in other crops. CLCuD incidence showed a significant negative genotypic correlation with yield-contributing traits followed by a significant negative association for phenotypic correlation. The seed cotton yield showed significant positive genotypic and phenotypic correlations with plant height, number of bolls per plant, and boll weight. From the PCA we identified five principal components (PCs) that explained a significant amount of the variance among the variables, which may be used for selection of cotton genotypes with CLCuD resistance. Of the five PCs, the first four contributed more towards the total variability and had eigenvalues greater than one. The cluster analysis showed that the genotypes in one of the clusters performed particularly well with respect to CLCuD tolerance. These genotypes can be utilized for development of varieties with increased CLCuD tolerance.

Estimation of genetic variability among peanut genotypes for resistance to leaf spot disease.

This study aimed to identify high-yielding peanut genotypes with resistance to leaf spot disease. The experiments included material from fourteen local and four exotic peanut genotypes that showed highly significant differences among morphological and disease severity parameters in all the genotypes which, in turn, suggested diversity genotypes. Disease severity analysis showed that the highest disease score and damaged leaf area were observed in the genotype Kelincer and the lowest scores and leaf damaged areas were observed in Majalaya super and BARI-2000, respectively. Based on these results, the genotypes BARI-2011, Chakori, Golden, BARI-89, Majalaya Super, BARD-699, BARI-2000, SP-1, and No. 334 can be used by breeders in peanut improvement programs for the development of new cultivars with higher disease resistance and increased yield.