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Jaladet M.S. Jubrael, Sripada M. Udupa, and Michael Baum

Currently, the identification and characterization of date palm varieties rely on a small number of morphological traits, mainly of fruit, which are complex and greatly influenced by the environment. As a result, different varietal names may actually refer to the same variety while different varieties may have the same name. Therefore, new descriptors like molecular markers are required to identify, characterize, and estimate genetic diversity in this crop. Here we used amplified fragment length polymorphism (AFLP) markers to discriminate 18 Iraqi date palm varieties and to estimate the genetic relationship among the varieties. A total of 122 polymorphic AFLP loci were scored, with an average of 17.4 polymorphic loci per primer combination. The use of any one of the four combinations, P101(aacg)/M95(aaaa), P74(ggt)/M95(aaaa), P73(ggg)/M95(aaaa), or P100(aacc)/M95(aaaa), was sufficient to uniquely identify all the varieties. Jaccard's genetic similarity index ranged from 0.108 to 0.756, indicating moderate to diverse relationships. Estimation of average proportion of fixed recessive AFLP loci indicated that most of the loci in variety `Chipchab' were fixed, whereas most of the loci in `Jamal Al-Dean' could be heterozygous and in-between in other varieties. Unweighted pair group method with arithmatic mean (UPGMA) analysis ordered the date palm varieties first into two broad groups at 27% similarity levels. One group consisted of seven varieties and the second group consisted of the remaining 11 varieties of date palm. These results showed that the AFLP technique is an efficient method for varietal identification and estimating genetic relationships in date palm.

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Min Deng, Jianjun Chen, Richard J. Henny, and Qiansheng Li

2 ij , in which P ij is the frequency of the j th allele for the i th locus. Genetic distances among the cultivars were calculated using the mean character difference (number of variable positions divided by number of nucleotides compared); both

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Benard Yada, Phinehas Tukamuhabwa, Bramwell Wanjala, Dong-Jin Kim, Robert A. Skilton, Agnes Alajo, and Robert O.M. Mwanga

marker in distinguishing one individual from another, was determined ( Weir, 1996 ) as: where Pi is the frequency of the i th allele. To investigate the diversity among the accessions, the number of alleles per locus was computed, and genetic distances

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Yu Cui, Jinsheng Wang, Xingchun Wang, and Yiwei Jiang

diversity, polymorphism information content (PIC), and pairwise Nei’s genetic distance ( Nei, 1972 ) were obtained using Powermarker v 3.25 ( Liu and Muse, 2005 ). Experimental design and statistical data analysis. The experiment was arranged in a split

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Robert D. Marquard, Eric P. Davis, and Emily L. Stowe

Forty selections, including 37 cultivars of Hamamelis spp., were evaluated for genetic similarities using randomly amplified polymorphic DNA (RAPD) markers. Cluster analysis identified seven groups, which included three groups of H. ×intermedia cultivars, two groups of H. vernalis, and one group each of H. mollis and H. japonica. Three H. ×intermedia cultivars, `Arnold Promise', `Westerstede', and `Carmine Red', did not group closely with the other 20 cultivars of H. ×intermedia. Selections of the North American species H. vernalis were quite distinct from the Asiatic selections. However, data are presented that suggest hybridization exist between Asiatic Hamamelis spp. and H. vernalis. Genetic similarities between known half-sib families provides evidence that the cultivar pairs `Arnold Promise'—`Winter Beauty' and `Carmine Red'—`Hiltingbury' are, themselves, not likely half-sibs.

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Jan Tivang, Paul W. Skroch, James Nienhuis, and Neal De Vos

The magnitude of genetic differences among and heterogeneity within globe artichoke cultivars is unknown. Variation among individual heads (capitula) from three artichoke cultivars and two breeding populations were evaluated using RAPD markers. One vegetatively propagated cultivar (`Green Globe'), two seed-propagated cultivars (`Imperial Star' and `Big Heart') and two breeding populations were examined. Two to thirteen polymorphic bands were observed for 27 RAPD primers, which resulted in 178 scored bands. Variation was found within and among all cultivars, and breeding populations indicating that all five groups represent heterogeneous populations with respect to RAPD markers. The genetic relationships among individual genotypes were estimated using the ratio of discordant bands to total bands scored. Multidimensional scaling of the relationship matrix showed five independent clusters corresponding to the three cultivars and two breeding populations. The integrity of the five clusters was confirmed using pooled chi-squares for fragment homogeneity. Average gene diversity (Hs) was calculated for each population sample, and a one-way analysis of variance showed significant differences among populations. `Big Heart' had an Hs value equivalent to the two breeding populations, while clonally propagated `Green Globe' and seed propagated `Imperial Star' had the lowest Hs values. The RAPD heterogeneity observed within clonally propagated `Green Globe' is consistent with phenotypic variability observed for this cultivar. Overall, the results demonstrate the utility of the RAPD technique for evaluating genetic relationships and contrasting levels of genetic diversity among populations of artichoke genotypes.

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Yan Liu, Hailin Guo, Yi Wang, Jingang Shi, Dandan Li, Zhiyong Wang, and Jianxiu Liu

visualized using a gel documentation system. The clear DNA bands were scored as 1 (present) or 0 (absent), and Nei’s genetic identity and genetic distance were computed by using POPGENE software 3.2 ( Yeh et al., 1997 ). Dendrograms were constructed with MEGA

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Karen R. Harris, Kai-Shu Ling, W. Patrick Wechter, and Amnon Levi

to several potyviruses ( Robaglia and Caranta, 2006 ; Ruffel et al., 2005 ). CAPS-1 and CAPS-2 markers are linked to the ZYMV-FL resistance gene locus in PI 595203, having a genetic distance of 6 and 10 cM in an F 2 population derived from the ZYMV

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Dong Liu, Ping Li, Jiulong Hu, Kunyuan Li, Zhenyu Zhao, Weiyan Wang, Jinyuan Zhang, Xu Ding, and Zhimou Gao

of the correlation between genetic distance and geographical distance among different geographic groups ( Miller, 1997 ). Analysis of molecular variance within and between P. sojae populations was evaluated according to Excoffier et al. (1992

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Matthew Chappell, Carol Robacker, and Tracie M. Jenkins

10,000 simulations. A matrix of Nei's unbiased genetic distances ( Nei, 1978 ) was calculated by PopGene version 3.2 using all markers, including monomorphs. Nei's unbiased genetic distance is the most accurate and reliable estimate of genetic