Switchgrass (Panicum virgatum L.) is a warm season, C 4 perennial grass native to most of North America with numerous applications, including use as a bioenergy feedstock species. To date, no studies on genetic diversity in switchgrass have been conducted that use both molecular and morphological markers. The objectives of this study were to assess genetic diversity and determine differences among and between 12 switchgrass populations grown in New Jersey by examining both morphological and molecular characteristics, and to determine whether morphological, molecular, and/or combined data sets can detect ecotype and/or geographical differences at the population level. Twelve plants from each population were characterized with 16 switchgrass expressed sequence tag-simple sequence repeat markers (EST-SSRs) and seven morphological characters. Data was analyzed using GenAlEx and Unweighted Pair-Group Method of Averages (UPGMA) cluster analysis. Most (64%) of the molecular variation in switchgrass populations exists among individuals within populations, with lesser amounts between populations (36%). Upland and lowland populations were distinguished in all three data sets. Some eastern US and midwestern US populations were distinct in all three data sets. Similarities were observed between all three data sets indicating molecular markers may be useful for identifying morphological differences or other adaptive traits. The combined data set was the most useful in differentiating populations based on geography and found separation between midwestern and eastern upland populations. The results indicate that the combination of morphological and molecular markers may be useful in future applications such as genetic diversity studies, plant variety protection, cultivar identification, and/or identifying geographic origin.

Kentucky bluegrass (Poa pratensis L.) is an important facultative apomictic temperate perennial grass species used for both forage and cultivated turf. Through apomixis, this species is able to propagate diverse and odd ploidy levels, resulting in many genetically distinct phenotypes. A wide range of diverse cultivars and accessions of kentucky bluegrass have been previously characterized based on pedigree, common turf performance, and morphological characteristics to create a kentucky bluegrass cultivar classification system. The objectives of the current study were to assess the amount of genetic divergence among kentucky bluegrass cultivars, experimental selections, and plant collections and revise/update the original pedigree, turf performance, and morphological characteristics kentucky bluegrass classification system using recently described kentucky bluegrass microsatellite [simple sequence repeat (SSR)] markers. In this study, 247 kentucky bluegrass cultivars, experimental selections, and collections were genotyped using 25 SSR markers. SSR markers showed a strong correlation between genetic relatedness as assessed by molecular markers and the original kentucky bluegrass classification system and also provided justification for a revision/update of the classification system. Traditional classification types that were supported by the current SSR analysis include BVMG, Compact, Compact-America, Julia, Mid-Atlantic, Midnight, and Shamrock types. Newly proposed classification types included Cynthia, Jefferson/Washington, Limousine, P-105, Sydsport, and three Eurasian types. The majority of cultivars, experimental selections, and collections were uniquely identified with the current set of SSR markers. Genetic relationships of individuals as assessed by SSR markers closely matched known pedigrees. The current set of SSR markers can be used to rapidly genotype and assign new cultivars/accessions to kentucky bluegrass classification types and assess genetic relatedness among individuals and should be considered for use in a kentucky bluegrass plant variety protection program.

The first genetic map of cranberry (Vaccinium macrocarpon) has been constructed, comprising 14 linkage groups totaling 879.9 cM with an estimated coverage of 82.2 %. This map, based on four mapping populations segregating for field fruit-rot resistance, contains 136 distinct loci. Mapped markers include blueberry-derived simple sequence repeat (SSR) and cranberry-derived sequence-characterized amplified region markers previously used for fingerprinting cranberry cultivars. In addition, SSR markers were developed near cranberry sequences resembling genes involved in flavonoid biosynthesis or defense against necrotrophic pathogens, or conserved orthologous set (COS) sequences. The cranberry SSRs were developed from next-generation cranberry genomic sequence assemblies; thus, the positions of these SSRs on the genomic map provide information about the genomic location of the sequence scaffold from which they were derived. The use of SSR markers near COS and other functional sequences, plus 33 SSR markers from blueberry, facilitates comparisons of this map with maps of other plant species. Regions of the cranberry map were identified that showed conservation of synteny with Vitis vinifera and Arabidopsis thaliana. Positioned on this map are quantitative trait loci (QTL) for field fruit-rot resistance (FFRR), fruit weight, titratable acidity, and sound fruit yield (SFY). The SFY QTL is adjacent to one of the fruit weight QTL and may reflect pleiotropy. Two of the FFRR QTL are in regions of conserved synteny with grape and span defense gene markers, and the third FFRR QTL spans a flavonoid biosynthetic gene.

and Kardos, 1963;Brown and Duble, 1975;Taylor and Blake, 1979;Baker and Richards, 1993). Much of these Sand-based root zones are commonly used for construction of golf previous reports emphasized physical properties of root course putting greens. Objectives of this field study were to (i) evaluate sand-based root zone mixtures varying in amendment (fine loam, zone mixtures, with more limited information provided peat, and inorganic) on the establishment of 'L-93' creeping bentgrass on turfgrass response. Identifying combinations of con-(Agrostis stolonifera L.), (ii) compare findings to related published struction materials that result in appropriate physical studies, and (iii) repeat the trial in two locations varying in air circulaproperties, as well as turfgrass response, would define tion to assess microenvironmental effect. Eleven root zone mixtures, the range of flexibility in material selection that is availusing predominantly medium-sized sand as the majority component, able for construction of a putting green root zone and were replicated four times in a randomized complete block design provide useful information to property developers connested within the two microenvironments. Plots were seeded in May ducting cost-benefit evaluations. 1998 and establishment was assessed to June 1999. Mixtures with a Material specifications for the construction of putting capillary porosity (Ϫ3 kPa water potential) at the high end of, or green root zones are available (Green Section Staff, slightly exceeding, the United States Golf Association (USGA) criterion range (0.15-0.25 m 3 m Ϫ3 ) provided more rapid establishment and 1993; Davis et al.

Stable genetic resistance to the fungal disease eastern filbert blight (EFB), caused by Anisogramma anomala, is vital for sustainable production of European hazelnut (Corylus avellana) in eastern North America. In this study, new hazelnut germplasm from the Russian Federation, Ukraine, and Poland (a total of 1844 trees from 66 seed lots) was subjected to A. anomala under field conditions over at least five years in New Jersey. Plants were then rated for the presence of EFB using an index of 0 (no disease) through 5 (all stems containing cankers). Nuts of the resistant trees were evaluated to identify plants with improved kernel characteristics. Genomic DNA of these trees was also screened with sequence-characterized amplified region (SCAR) markers generated by the primers BE-03, BE-33, and BE-68, which are closely linked to the single dominant R-gene of ‘Gasaway’, to assess the resistant seedlings for the presence of this well-known source of resistance. At final evaluation, 76 trees remained free of disease with nine expressing only minor symptoms (rating 1 or 2). The resistant trees spanned 24 different seed lots representing all three countries. The remaining trees ranged from moderately to severely infected with 81% of the total collection rating 5. Several of the resistant trees were found to produce commercial-sized (≈12 mm diameter), round kernels that blanched well. Although the results of the ‘Gasaway’ SCAR primers were inconclusive, the diverse collection origins and disease phenotypes provide evidence that novel sources of resistance were likely identified in this study. These new plants should broaden the genetic base of EFB-resistant C. avellana hazelnut germplasm available for breeding.