triploid seeds ( Shimotsuma and Matsumoto, 1957 ). Still, DNA markers can be useful in quality assurance tests to confirm sufficient production of triploid seeds in isolation plots. DNA markers have been used in genetic studies and in breeding programs of
Beibei Li, Jianfu Jiang, Xiucai Fan, Ying Zhang, Haisheng Sun, Guohai Zhang, and Chonghuai Liu
Development and characterization of additional microsatellite DNA markers for grape Amer. J. Enol. Viticult. 50 243 246 Bowers, J.E. Dangl, G.S. Vignani, R. Meredith, C.P. 1996 Isolation and characterization of new polymorphic simple sequence repeat loci in
Dror Sharon, Jossi Hillel, Samir Mhameed, Perry B. Cregan, Emanuel Lahav, and Uri Lavi
The detection of association between DNA markers and traits of interest in an outbred population is complicated and requires highly polymorphic markers. A genetic linkage map of avocado (Persea americana Mill.) recently generated consists of simple sequence repeat (SSR) markers as well as DNA fingerprint (DFP) and randomly amplified polymorphic DNA (RAPD) markers. These markers were used to detect putative quantitative trait loci (QTLs) of eight avocado fruit traits. Two statistical methods were used: one-way analysis of variance and interval mapping. Six traits were found to be associated with at least one of the 90 DNA markers. Based on the two statistical approaches, a putative QTL associated with the presence of fibers in the flesh, was found to be located on linkage group 3. This putative QTL was found to be associated with the SSR marker AVA04 having a high significant value (P = 4.4 × 10-8). The haplotype analysis of linkage group 3 showed a putative dominant interaction between the alleles of this locus.
C.S. Prakash, Guohao He, and Robert L. Jarret
The polymerase chain reaction (PCR)-based DNA amplification fingerprinting (DAF) approach was used to investigate genetic relationships among 30 U.S. sweetpotato (Ipomoea batatas L. Lam.) genotypes including heirloom cultivars and recent releases. Phenogram, pairwise similarity matrix, and principal coordinate plots were developed based on Jaccard's coefficients using band-sharing data generated by seven octamer primers. All cultivars showed unique fingerprint patterns indicating the utility of DAF in cultivar identification. Many heirloom cultivars such as `Creole' and `Porto Rico' were readily differentiated from recently developed cultivars. Modern cultivars such as `Jewel', `Carver', `Nugget', and `Scarlet' exhibited a high degree of similarity reflecting ancestral relatedness. `Regal' and `Excel', recently developed using a population-based breeding approach, showed greater divergence from all other cultivars. Those cultivars, developed as a result of somatic mutations, exhibited high levels of genetic similarity to their normal-type parents and yet had distinct fingerprint profiles. With few exceptions, genetic relationships derived from DAF data appear to be consistent with available pedigree information.
Donglin Zhang, Michael A. Dirr, and Robert A. Price
The correct identification of horticultural taxa becomes more and more important for intellectual property protection and economic reasons. Traditionally, morphological characteristics have been used to differentiate among the horticultural taxa. However, the morphological characteristics may vary with plant age, cultural conditions, and climate. Modern technologies, such as DNA markers, are now employed in the identification of horticultural taxa. Currently, technologies of DNA sequencing (gene sequences) and DNA fingerprinting (RAPD, RFLP, SSR, and AFLP) are available for distinguishing among horticultural taxa. The literature and our personal experience indicate that the application of each technique depends on the taxon and ultimate goal for the research. DNA sequencing of a variety of nuclear or chloroplast encoded genes or intergenic spacers (rbcL, ndhF, matK, ITS) can be applied to distinguish different species. All DNA fingerprinting technologies can be used to classify infraspecies taxa. AFLP (the most modern technique) is the better and more-reliable to identify taxa subordinate to the species, while RAPDs can be employed in clonal or individual identification. Techniques of RFLP and SSR lie between AFLP and RAPD in their effectiveness to delineate taxa. Mechanics, laboratory procedures, and inherent difficulties of each technique will be briefly discussed. Application of the above technologies to the classification of Cephalo taxus will be discussed in concert with the morphological and horticultural characteristics. Future classification and identification of horticultural taxa should combine DNA technology and standard morphological markers.
Hong Xu and Alan T. Bakalinsky
Five sequence characterized amplified region (SCAR) DNA markers were reevaluated at substantially higher annealing temperatures than originally reported; four were polymorphic among nine rootstocks tested. Four new informative SCAR markers also are reported, based on redesigning primers from previously cloned random amplified polymorphic DNA (RAPD) markers. Based on the eight polymorphic markers, rootstocks MG 420A, MG101-14, Richter 99, Couderc 3309, and Kober 5BB were distinguishable. Riparia Gloire and Couderc 1616 could be distinguished from the others, but not from one another, and SO4 and 5C also could be distinguished from the others, but not from one another.
Xiaohan Yang, Brian E. Scheffler, and Leslie A. Weston
Primer design is a critical step in the application of PCR-based technologies in genetic diversity analysis of horticultural plants. As more plant genomes have been sequenced in recent years, the emphasis of primer design strategy has shifted to genome-wide and high-throughput direction. This poster summarizes recent advances in primer design for profiling of DNA polymorphism in higher plants, including new primers for the classical plant DNA marker system such as simple sequence repeat (SSR) and single-nucleotide polymorphism (SNPs), as well as newly developed DNA marker systems such as sequence-related amplified polymorphism (SRAP), sequence-specific amplification polymorphism (SSAP), target region amplification polymorphism (TRAP), and universal rice primer (URP). Although most of these primers were designed for agronomical crops, they could be applied to horticultural plants because plant genomes are evolutionarily related. Also, these new primer design strategies could help horticultural researchers develop better primers specifically for profiling of polymorphism in a variety of horticultural crops, invasive weeds, or medicinal plants. We will present examples of their utilization in these diverse systems.
Kang-Hee Cho, Il-Sheob Shin, Seong-Sig Hong, Ki-Taek Kim, Hwa-Suk Song, Sang-Jo Kang, and Il Gin Mok
Pear scab caused by Venturianashicolais one of the most important diseases of oriental pear. Breeding a variety resistant to scab can be improved through marker-assisted selection (MAS). Bulked segregant analysis (BSA) and amplified fragment length polymorphic (AFLP) analysis were performed to identify DNA markers linked to the scab-resistant gene (Vn) using a population from a cross between PS2-93-3-98 (resistant parent) and Yali (susceptible parent). A total of 480 EcoR I/MseI primer combinations were used to identify markers specific to PS2-93-3-98 and resistant pool. Three AFLP markers linked to Vn, E-AGT/M-CCA245, E-ATT/M-CCG300, and E-GGT/M-TCT225, were selected. Linkage analysis between the selected markers and Vn locus was conducted with 51 individual plants. The selected markers, E-AGT/M-CCA245, E-ATT/M-CCG300, and E-GGT/M-TCT225, were located at 3.9, 3.8, and 1.2 cm away from Vn, respectively. For practical application, we are currently converting selected markers to simple PCR-based markers. The markers could be used to increase selection efficiency in pear-breeding programs for scab resistance.
Melissa T. McClendon, Debra A. Inglis, Kevin E. McPhee, and Clarice J. Coyne
Dry pea (Pisum sativum L.) production in many areas of the world may be severely diminished by soil inhabiting pathogens such as Fusarium oxysporum f. sp. pisi race 1, the causal organism of fusarium wilt race 1. Our objective was to identify closely linked marker(s) to the fusarium wilt race 1 resistance gene (Fw) that could be used for marker assisted selection in applied pea breeding programs. Eighty recombinant inbred lines (RILs) from the cross of Green Arrow (resistant) and PI 179449 (susceptible) were developed through single-seed descent, and screened for disease reaction in race 1 infested field soil and the greenhouse using single-isolate inoculum. The RILs segregated 38 resistant and 42 susceptible fitting the expected 1:1 segregation ratio for a single dominant gene (χ2 = 0.200). Bulk segregant analysis (BSA) was used to screen 64 amplified fragment length polymorphism (AFLP) primer pairs and previously mapped random amplified polymorphic DNA (RAPD) primers to identify candidate markers. Eight AFLP primer pairs and 15 RAPD primers were used to screen the RIL mapping population and generate a linkage map. One AFLP marker, ACG:CAT_222, was within 1.4 cM of the Fw gene. Two other markers, AFLP marker ACC:CTG_159 at 2.6 cM linked to the susceptible allele, and RAPD marker Y15_1050 at 4.6 cM linked to the resistant allele, were also identified. The probability of correctly identifying resistant lines to fusarium wilt race 1, with DNA marker ACG:CAT_222, is 96% percent. These markers will be useful for marker assisted breeding in applied pea breeding programs.
Xiao-min Liu, Xin-zhi Zhang, Yi-min Shi, and Dong-qin Tang
resources ( Franco et al., 2001 ; Zhang and Dai, 2010 ). The methods for analysis of genetic diversity in plants were well developed in the last decades, commonly based on the morphological characteristics, seed proteins, isozymes, and DNA markers ( Gepts