The population genetic structure of 278 Venturia inaequalis isolates, collected from different apple cultivars of eighteen different provinces in Iran, was investigated using 22 polymorphic microsatellite markers. Analysis of molecular variation, Bayesian clustering and Nei's genetic distance analyses based on 88 microsatellite alleles indicated substantial levels of gene flow among the collection sites. Ninety three percent of the variation was observed among the individuals within the populations and only 7% variation was observed among the populations. Structure analysis grouped the isolates into two populations. Maximum number of pathogen genotypes (44) was observed in the North of Iran that grows various different apple cultivars. Investigation on the variation of the pathogen on different cultivars in the North of Iran suggested a significant differentiation of the pathogen populations between wild apple and commercial cultivars. During sampling, varying ranges of scab infection were observed on various apple cultivars in forests, monoculture and mix orchards. Wild type apple (Malus orientalis) along the Caspian Sea Coast had the most infection in comparison with the Iranian endemic and commercial cultivars. Based on the genetic analysis and host tracking scenario of the pathogen, it was presumed that Iran could potentially be the center of origin of V. inaequalis, which requires further detailed studies with isolates collected from different parts of central Asia and world for confirmation.

Sugarcane crop is important for both sugar and biofuels. A world collection of sugarcane and related grasses (WCSRG) maintained at Miami, FL contains > 1,200 non-redundant clones of different species and genera within the Saccharum complex. However, linkage of undesirable alleles with useful genes in wild species has hindered its efficient utilization in sugarcane breeding. A core collection developed previously with smaller number of clones representing WCSRG did not take into account > 120 wild/ exotic clones maintained at the USDA-ARS Sugarcane Research Unit in Houma, Louisiana. Moreover, the genome complexity and subtropical to temperate growing climate of Louisiana warrant a regionspecific core collection that can be used for base-broadening breeding aimed at efficient introgression of desirable alleles. Genetic diversity of 1,485 clones within WCSRG and Louisiana (commercials, wild/ exotic) using 423 SSR alleles showed an average gene diversity (h) at 0.208 among all species groups where Erianthus-like Saccharum species (ELSS), Miscanthus spp., and S. spontaneum each formed a distinct cluster, Saccharum robustum, S. officinarum, hybrid cultivars, and S. edule grouped together in a major cluster, and Saccharum sinense and S. barberi formed distinct grouping. A 309-clone diversity panel (SDP1) was developed that captured the genetic diversity based on the combination of maximum length subtree and manual selection to maximize representation of Louisiana clones and minimize import of clones from Miami. SDP1 shared 324 alleles out of the 423 alleles in the entire population of 1,485 clones and captured the genetic diversity of the entire collection with an average gene diversity (h) at 0.163. The variation within (11-17%) and among (83-89%) the populations in SDP1 were comparable with the entire population of 1,485 clones (9-15% and 85-91%, respectively). The breadth of the genetic variation of SDP1 was exemplified by the intra-and inter-specific diversity of a 190-clone mini-core collection with markers derived from known cold-responsive genes. SDP1 will facilitate genome-wide association studies for identification of trait-specific markers for use in markerassisted breeding in Louisiana and elsewhere. Cultivated sugarcane (Saccharum interspecific hybrids) is a perennial C 4 grass crop belonging to the subtribe Saccharinae under the tribe Andropogoneae of the family Poaceae. Sugarcane is cultivated worldwide in tropical and subtropical regions as a major source of sucrose 1 , with a global crop value of $61 billion per year 2. Sugarcane accounts for 80% of global sucrose production and 45% of sucrose production in the United States 3. Sugarcane, in addition to its importance as a food crop, is recognized as the most productive bioenergy crop because of its ability to produce high biomass 4. Historically, six species are considered important in the Saccharum genus, which include two wild species, S. spontaneum (L.) (2n = 40-128) and S. robustum (Brandes & Jesw. Ex Gressl) (2n = 60, 80), and four domesticated

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