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Apple scab instigated by Venturia inaequalis impels remarkable losses to apple fruit production. In an effort to comprehend the key mechanisms of evolutionary potential defining V. inaequalis population, 132 isolates of V. inaequalis from five commercial apple orchards were collected and assayed using 14 microsatellite markers. The average diversity was observed within the individuals of populations based on the Shannon-Wieners index (I) and observed heterozygosity (Ho) was average but considerably lower than expected heterozygosity (He). The genetic differentiation based on FST values was revealed as an average measure of divergence between populations and had varying proportions of gene flow and migration among themselves. Analysis of Molecular Variance (AMOVA) revealed that variance (94%) was dispersed across individuals with a significant (6%) variation between populations from different regions. To examine host specialization within the V. inaequalis population, the assignment approach based on K-means of clustering (an unsupervised machine learning approach), revealed that the clustering method supported three clusters at (K = 3) and three major clusters were also observed in Principle Component Analysis (PCA). Additionally, Nei's genetic distance values, pairwise estimates of genetic differentiation, dendrogram using the neighbor-joining and PCoA revealed the random distribution of V. Inaequalis isolates that depicted a high proportion of genotypic diversity within populations and population genetic structure. [ABSTRACT FROM AUTHOR]

The present study was aimed to evaluate adaptive mechanism in terms of seed characters of Phyllanthus amarus collected from ten different locations of Tamil Nadu, India. The adaptive variations among the collected populations were assessed based on the sink and float percentages of the seeds in water, the percentage of seed germination, total protein, carbohydrates and their seedling’s growth ability such as shoot and root lengths. From this, we observed that the population had a significantly higher germination percentage of sinking seeds that were attributed to its relatively higher carbohydrate and protein contents than the floating seeds. A comparison of the seed population by cluster analysis and principal coordinate analysis showed that the Chennai population constituted a single clade that was very distinct from the other nine populations, which were further grouped into two sub-clusters. They exhibited a trend consistent with their geographical proximity. Standardised Mantel’s t tests had revealed that the adaptive diversity of the P. amarus population was significantly affected by the geographic distance (r = 0.78, t = 2.68, P > 0.001), altitude (r = 0.35, t = 21.53, P > 0.05), minimum temperature (r = 0.43, t = 1.49, P > 0.01) and maximum temperature (r = 0.49, t = 1.67, P > 0.001). Seed’s characteristics and geographical conditions were correlated along with 19 bioclimatic variables. In dry season, the seedling’s rooting ability showed positive correlation, while its protein content exhibited a negative correlation. It is clearly evident from this study that the geographical variables significantly influence the adaptive ability of the P. amarus. [ABSTRACT FROM AUTHOR]