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Eugene K. Blythe and Donald J. Merhaut

, nonparametric methods can be used ( Hollander and Wolfe, 1999 ). A wide variety of goodness-of-fit tests are available to assess the normality of sample data from a single population or, in the cases of linear regression analysis and analysis of variance, from

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Haejeen Bang, Angela R. Davis, Sunggil Kim, Daniel I. Leskovar and Stephen R. King

chromatography (HPLC) analysis. Leaf tissues were collected and stored individually at −20 °C for genotype analysis. Statistical analysis. The number of genes involved in color determination for each cross was estimated by the chi-square goodness-of-fit

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I.L. Goldman and J.F. Watson II

A severe dwarf mutant affecting vegetative and reproductive growth arose spontaneously in our red beet (Beta vulgaris L. subsp. vulgaris) breeding nursery and was used in crosses with inbred lines to characterize its inheritance. Segregation data in backcross and F2 generations were collected. Chi-square goodness-of-fit tests did not deviate significantly from the expected ratios for a monogenic character for each genetic background-generation combination. We propose the symbol dw to describe the genetic control of this dwarf phenotype. Greenhouse experiments were conducted to determine whether the mutant was sensitive to exogenous application of gibberellic acid (GA). GA3 and GA4/7 in concentrations of 0 to 1000 ppm were applied to apical meristems during flower stem development in vernalized dwarf plants. Data on flower stem length and leaf length were collected over a 6-week period during reproductive growth. Recovery of wild-type flower stem length was obtained with application of both types of GA. A 30-fold increase in flower stem length over untreated plants was accomplished by GA application. Results of these phenocopy experiments suggest the mutant gene is involved in GA synthesis.

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I.L. Goldman

A fasciated flower stem character arose spontaneously during development of the red beet (Beta vulgaris L.) inbred line W411. The fasciated character is manifest by a flattened flower stem with petioles coalesced into a twisted, ribbonlike appearance. No fasciation is present in the vegetative stem or petioles. An inheritance study was conducted to determine the genetic control of flower stem fasciation. The inbred line W411 was used both as a male and female parent in crosses with four red beet inbred lines. Segregating progenies in both the BC1 and F2 generations were developed and scored for the fasciated flower stem character. Variable expression of the fasciated flower stem phenotype was observed in these progenies; however, the presence of flattened flower stems at the stem-hypocotyl junction was unequivocal. Chisquare goodness-of-fit tests in the BC1 and F2 generations did not deviate significantly from expected ratios for a monogenic recessive character for each genetic background. No reciprocal differences were detected for any cross in this group of four inbred lines, which suggests the lack of maternal effect for the fasciated character. The symbol ffs is proposed to describe the genetic control of the fasciated flower stem phenotype.

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Paul D. Mangum and Ellen B. Peffley

The inheritance and linkage relationships among PGM-1, ADH-1, and 6-PGDH-1 were determined for Allium fistulosum (Japanese bunching onion) individuals. Individuals expressing Pgm-11/Pgm-12, Adh-13/Adh-14, Adh-13/Adh-15, or 6-Pgdh-11/6-Pgdh-12 were selfed seperately. These backcrosses and their reciprocals were made: Pgm-11/Pgm-12 to Pgm-11/Pgm-11 or Pgm-12/Pgm-12; Adh-13/Adh-14 to Adh-13/Adh-13 or Adh-14/Adh-14, 6-Pgdh-11/6-Pgdh-12 to 6-Pgdh-11/6-Pgdh-11 or 6-Pgdh-12/6-Pgdh-12. Progeny segregations were tested for Mendelian inheritance using a chi-square goodness of fit test. Expression of 6-Pgdh has not been previously reported in onion. Two zones of activity were detected and were designated as 6-PGDH-1 and 6-PGDH-2. 6-PGDH-2 was monomorphic for all individuals tested. Progeny segregation of 6-PGDH-1 fit a model for a dimeric enzyme encoded by one disomic locus with two alleles, expressed as fast (1) and slow (2), in a dimeric enzyme pattern in heterozygous individuals.

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A.C. Arcinas, B.S. Sipes, A.H. Hara and M.M.C. Tsang

Exporters of potted nursery stock face strict quarantine regulations against the burrowing nematode, Radopholus similis. Currently, there are no treatments approved by quarantine authorities to disinfest plants of R. similis. Interceptions of the nematode lead to significant economic loss and curtailment of trade, therefore hot-water drench treatments were investigated for quarantine utility. Drenches with 50 °C water were applied for 10 to 16 minutes to two economically important palm species, rhapis (Rhapis excelsa) and fishtail (Caryota mitis). Plants were inoculated with 5,000 mixed life stages of R. similis and allowed to establish for 14 weeks before drench treatments. In rhapis, a moderately good host to R. similis, a 16-minute hot water drench had high efficacy, achieving 99.6% mortality. In fishtail, a poor host, all treatments longer than 10 minutes at 50 °C eliminated R. similis from the plants. Probit regression estimates of the LT99, were 16.9 and 10.3 minutes respectively. However χ2 goodness-of-fit tests were significant (χ2 = 21.136, df = 3, p < 0.0001) for rhapis. Since most observed values were between the 95% fiducial limits, this suggests that the large χ2 value was caused by variability in response or insufficient repetitions rather than an inappropriate model. A χ2 statistic could not be computed for fishtail because poor host status led to variances that were nearly equal to zero. The high efficacy of hot water drenches for the control of R. similis is approaching the Probit 9 standard of 99.9968% mortality required for approval as a quarantine treatment.

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Hongwen Huang, Desmond R. Layne and Thomas L. Kubisiak

Twelve, 10-base primers amplified a total of 20 intense and easily scorable polymorphic bands in an interspecific cross of PPF1-5 pawpaw [Asimina triloba (L.) Dunal.] × RET (Asimina reticulata Shuttlew.). In this cross, all bands scored were present in, and inherited from, the A. triloba parent PPF1-5. Nineteen of the 20 bands were found to segregate as expected (1:1 or 3:1) based on chi-square goodness-of-fit tests, and were subsequently used to evaluate genetic diversity in populations of A. triloba collected from six states (Georgia, Illinois, Indiana, Maryland, New York, and West Virginia) within its natural range. Analysis of genetic diversity of the populations revealed that the mean number of alleles per locus was A = 1.64, percent polymorphic loci was P = 64, and expected heterozygosity was He = 0.25. No significant differences were found among populations for any of the polymorphic indices. Partitioning of the population genetic diversity showed that the average genetic diversity within populations was Hs = 0.26, accounting for 72% of the total genetic diversity. Genetic diversity among populations was Dst = 0.10, accounting for 28% of the total genetic diversity. Nei's genetic identity and distance showed a high mean identity of 0.86 between populations. Genetic relationships among the populations examined by unweighted pair-group mean clustering analysis separated the six populations into two primary clusters: one composed of Georgia, Maryland, and New York, and the other composed of Illinois, Indiana, and West Virginia. The Georgia and Indiana populations were further separated from the other populations within each group. This study provides additional evidence that marginal populations within the natural range of A. triloba should be included in future collection efforts to capture most of the rare and local alleles responsible for this differentiation.

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Joanne A. Labate, Larry D. Robertson, Angela M. Baldo and Thomas Björkman

Broccoli (Brassica oleracea L. var. italica Plenck) and cauliflower (B. oleracea var. botrytis DC) are closely related botanical varieties. The underlying genetic bases of their phenotypic differences from each other are not well understood. A molecular genetic marker enabling B. oleracea germplasm curators and breeders to predict phenotype from seeds or seedlings would be a valuable tool. Mutant alleles at flower developmental pathway loci BoAP1-a, Bo-CAL-a, and glucosinolate biosynthetic pathway locus BoGSL-ELONG have been reported to be associated with a cauliflower phenotype. We surveyed mutant alleles at these three loci in a genetically diverse sample of broccoli and cauliflower accessions from the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS) Plant Genetic Resources Unit (PGRU) and the University of Warwick, Genetic Resources Unit of Warwick HRI (HRI). Phenotypic and genotypic data were collected for multiple plants per accession during two field seasons. Simple genetic models assuming dominance or codominance of alleles were analyzed. Goodness-of-fit tests rejected the null model that the mutant genotype was associated with a cauliflower phenotype. A correlation analysis showed that BoAP1-a and BoCAL-a alleles or loci were significantly correlated with phenotype but the fraction of variation explained was low, 4.4% to 6.3%. Adding BoGSL-ELONG to the analysis improved predictive power using the linear regression procedure, Maximum R-square Improvement (max R 2). In the best three-variable model, only 24.8% of observed phenotypic variation was explained. Because tested genetic models did not hold robustly for the surveyed accessions, it is likely that there are multiple genetic mechanisms that influence whether the phenotype is broccoli or cauliflower. Our results in commercial cultivars indicate that other genetic mechanisms are more important in determining the horticultural type than are BoAP1-a and BoCAL-a.

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Lingli Lou and Todd C. Wehner

. Segregation analysis and goodness-of-fit tests were performed based on χ 2 testing of the expected segregation ratios for a single gene, using the SAS-STAT statistical package (SAS Institute, Cary, NC) and the SASGene 1.2 program ( Liu et al., 1997 ). The

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Gabriele Gusmini, Luis A. Rivera-Burgos and Todd C. Wehner

segregation analysis and the chi-square goodness-of-fit tests ( P < 0.05) for each F 2 and BC 1 P r progeny with the SAS-STAT statistical package (SAS Institute, Cary, NC) and the SASGENE 1.2 program ( Liu et al., 1997 ). Yate’s correction was used for