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Roberto A. Young and James D. Kelly

We acknowledge P.N. Miklas for developing the Middle American population; N. Weeden for the initial identification of the linked B355 1000 RAPD marker, and L. Afanador for assisting with disease screening. This research was supported in part by the

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Ghazal Baziar, Moslem Jafari, Mansoureh Sadat Sharifi Noori, and Samira Samarfard

assessed by calculating the percentage of polymorphic bands (PPB). The information content of each RAPD marker was computed as , where P i and P j are the frequency of the i th and j th observation, respectively, and k represents the number of

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Kai-Ge Zhao, Ming-Qin Zhou, Long-Qing Chen, Donglin Zhang, and Gituru Wahiti Robert

correlation coefficient between RAPD and ISSR data sets was 0.62, indicating that the two methods had a positive correlation in this study. Dendrogram obtained with ISSR and RAPD markers. Because the combined data would give a better coverage of the

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Liang L. Hong and Paul G. Thompson

Random amplified polymorphic DNA (RAPD) markers were analyzed in parents and progeny of four sweetpotato crosses. An average of 69 primers were tested and 23.5% produced well resolved polymorphic banding patterns. Each polymorphic primer had an average of 1.9 polymorphic bands resulting in 0.45 polymorphic fragments per primer tested. Phenotypic segregation ratios of 88% of polymorphic fragments fit those expected for hexaploid Mendelian inheritance. Numbers of linked polymorphic fragments and numbers of linkage groups were 13 and 5 for Cross A, 0 and 0 for Cross B, 23 and 3 for Cross C and 16 and 6 for Cross D. Those results indicated that RAPD markers have potential for a genetic linkage map in sweetpotato; however, many primers must be screened.

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Kuniaki Sugawara, Atsushi Oowada, Takaya Moriguchi, and Mitsuo Omura

Random amplified polymorphic DNA (RAPD) markers were used to detect chimerism of citrus cultivars. Polymerase chain reaction conditions suitable for discriminating citrus chimeras were determined. Primers that produced consistent and repeatable bands that differed between the parental cultivars were chosen to create discriminating band patterns. Our results show that selected 12-mer primers can be useful for identifying the four citrus chimeras tested using RAPD technology.

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J. Lu, O. Lamikanra, Y. Wang, Z. Liu, and D. Ramming

The grape is an important horticultural crop that is grown worldwide. Breeding a new grape cultivar by conventional means normally will take several generations of backcross, at least 15 years. The efficiency and speed of selection can be accelerated if genetic markers are available for early screening. This project is designed to generate RAPD markers linked to viticulturally important traits, including seedlessness and pistillate genes. A F1 population with 64 progenies of V. vinifera was used for the RAPD analysis. Bulked Segregant Analysis (BSA) method was used for RAPD primer screening. Three-hundred primers were screened between the two pairs of pooled DNA samples, seeded and seedlessness, pistillate and perfect flowers. At least 10 primers produced one polymorphism each between the pools. Further analysis revealed that one of these RAPDs cosegregated tightly with the seedlessness trait, while the others either had loose linkage or no linkage to the traits. To make the RAPD marker useful for breeding selection, an attempt was made to convert it into SCAR marker. The results demonstrated that the RAPD marker may be useful for grape breeding and interpreting inheritance of a particular trait in grapes.

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Liang L. Hong, Kittipat Ukoskit, and Paul G. Thompson

Parents and progeny of four biparental crosses were analyzed for RAPD marker segregation. A range of 57 to 122 primers were tested in each cross, with an average of 82. Average polymorphic primers and band numbers were 22 and 53, respectively. Of the 212 polymorphic bands, phenotypic segregation ratios were as follows: 133 fitted 1 dominant: 1 recessive, 58 fitted 3:1, 11 fitted ratios 4:1 to 19:1 and 10 were distorted. The 1:1 and 3:1 ratios were expected for either diploid or hexaploid segregation, and the 4:1 to 19:1 are exclusive to hexploid. A total of 14 pairs of markers were linked at map distances ranging from 2.1 to 36.5 cM. One common pair of linked markers was found in two separate crosses.

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C.H. Jan, D.H. Byrne, J. Manhart, and H. Wilson

The genus Rosa consists of more than 100 species classified into four subgenera, Eurosa, Platyrhodon, Hesperhodos, and Hulthemia, and distributed widely throughout the northern hemisphere. The subgenus Eurosa includes 11 sections. The other subgenera are monotypic. One hundred and nineteen accessions and 213 markers of 36 rose species that include eight sections of the subgenus Eurosa and one species each from the subgenera Hesperhodos and Platyrhodon were used to calculate a similarity matrix, which was clustered with the unweighted pair group method using arithmetic means (UPGMA). The RAPD markers distinguished between all the rose accessions, and species grouped into their respective sections. Therefore, classification of Rosa using RAPD data generally supports traditional classification. The Asian rose sections (Laevigatae, Banksianae, Bracteatae, Pimpinellifoliae, Chinenses, and Synstylae) were consistently separated from the primarily North American sections (Cassiorhodon and Carolinae). The Cassiorhodon and Carolinae sections were grouped together with the subgenera Hesperhodos and Platyrhodon. Both subgenera separated out at the same level as sections within the subgenus Eurosa, suggesting that they are more appropriately classified as sections within the subgenus Eurosa. Sections Cassiorhodon and Carolinae overlapped, and are probably best grouped as one section as previously suggested.

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Patricia M. Sweeney and T. Karl Danneberger

As the number of perennial ryegrass (Lolium perenne L.) cultivars increases, the development of reliable identification methods becomes more important. Randomly amplified polymorphic DNA (RAPD) markers show promise in cultivar identification. Since perennial ryegrass cultivars are composites of genotypes rather than a single genotype, finding markers that distinguish cultivars is difficult. The ideal cultivar identification procedure would use seed tissue as a DNA source and evaluate a single sample as representative of a cultivar. The objective of this research was to determine whether RAPD markers could be used to consistently distinguish bulk seed samples of perennial ryegrass cultivars. Two extraction protocols were evaluated. A quick, simple extraction resulted in the amplification of few consistent RAPD markers. The more labor-intensive extraction with hexadecyltrimethyl ammonium bromide (CTAB), however, produced more reliable RAPD markers. Eight of 11 cultivars were distinguished by using RAPD markers produced using bulk seed samples together with four of 30 primers that were screened. These results show the potential of RAPD markers to provide the turfgrass industry, breeders, and certification agencies additional options to ensure the genetic integrity of perennial ryegrass seed lots and cultivars.

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Paul Skroth, Jim Nienhuis, Geunhwa Jung, and Dermont Coyne

Knowledge of genetic relationships and genetic diversity among accessions is essential for the efficient construction, maintainance and utilization of large ex-situ germplasm collections. Furthermore, streamlining of large collections into care collections necessitates validation of germplasm sampling techniques. DNA molecular markers provide potentially unbiased estimators of genome diversity end may facilitate organization, maintainance, and sampling of plant genetic resources. Our data suggests that RAPD markers will be o good tool for testing tore collection concepts and organizing genetic diversity in common bean. However, the genomic distribution of markers is unknown. Currently we are using recombinant inbred (RI) populations to place RAPD markers in the context of the bean genetic map. We hove evaluated the the distribution of RAPD markers in three RI populations: Bat93 × Jalo EEP558, PC50 × Xan159, and BAC6 × HT7719. Cultivated P.vulgaris has two primary renters of diversity Mesoamerican and Andean, the RI populations used for mapping RAPD markers ore Meso × Andean, Andean × Andean, and Meso × Meso crosses respectively. In the Bat93 × Jalo EEP558 population 383 markers have been mapped for a map length of 735 cM. However, approximately 150 of these markers ore members of 9 dusters which span only 90 cM. This inter gone pool mop is being integrated with linkage mops constructed in the other two populations to compare within and between gene pool marker distributions and to evaluate clustering of markers on the different mops. Implications for the application of RAPD markers will be discussed.