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Filho J.M.,University of Sao Paulo | Francisco Jr. G.G.,University of Sao Paulo | Bennett M.A.,Ohio State University | Wells A.A.,Ornamental Plant Germplasm Center | Stieve S.,OPGC OSU
Revista Brasileira de Sementes | Year: 2010

A primary interest of image analysis of X-rayed seeds is to identify whether the extent of fill in the embryo cavity is associated with to seed physiological quality. The objective of this research was to verify the accuracy of the freely available Tomato Analyzer (TA) software developed at The Ohio State University to determine the ratio of embryo size over total seed area. Seeds of pumpkin, watermelon, cucumber and cotton were X-rayed and analyzed by the software which defines seed and embryo boundaries and automatically generates numerical values to quantify that ratio. Results showed that the TA has the sensitivity to evaluate the extent of embryo growth within the cucurbits and cotton seeds and is a promising alternative for this assessment in other seed species.

Zale P.J.,Ornamental Plant Germplasm Center | Zale P.J.,Ohio State University | Zale P.J.,Longwood Gardens Inc. | Jourdan P.,Ornamental Plant Germplasm Center | And 2 more authors.
Journal of the American Society for Horticultural Science | Year: 2015

Phlox is an important genus of herbaceous ornamental plants previously targeted for germplasm development, characterization, and enhancement by the U.S. Department of Agriculture, National Plant Germplasm System. Among Phlox in cultivation, Phlox paniculata is the most widely grown and intensively bred species, but little is known about variation in genome size and ploidy of this species or of related taxa that may be used for germplasm enhancement. The objective of this study was to assess cytotype variation in a diverse collection of cultivars and wild germplasm of P. paniculata (subsection Paniculatae) and of related taxa in subsections Paniculatae and Phlox. The collection included 138 accessions from seven species and two interspecific hybrids. Flow cytometry was used to estimate holoploid (2C) genome sizes and to infer ploidy levels. Chromosome counts were made to calibrate ploidy with genome size for a subset of taxa. Most cultivars were diploid (2n = 2x = 14) and had mean genome sizes that did not vary between subsections Paniculatae (14.33 pg) and Phlox (14.23 pg) although size variation was greater among cultivars within subsection Phlox. Triploid cultivars of P. paniculata, with a mean genome size of 21.36 pg and mitotic chromosome counts of 2n = 3x = 21, were identified. Such triploids suggests previous interploid hybridization within this taxon. Five tetraploid (2n = 4x = 28) cultivars were found in subsection Phlox; all were selections of P. glaberrima ssp. triflora, and had a mean genome size of 25.44 pg; chromosome counts in one of these confirmed they were tetraploid. The putative hybrid Phlox Suffruticosa Group ‘Miss Lingard’ showed an intermediate genome size of 21.21 pg supporting a triploid, hybrid origin of this taxon. Mean 2C genome sizes among wild-collected accessions were similar to values reported for cultivars (Paniculatae = 14.59 pg, Phlox = 14.23 pg), but taxa in subsection Phlox exhibited greater variation that included two tetraploids identified among wild-collected accessions; one, of P. pulchra, had a mean genome size of 26.17 pg, representing the first report of polyploidy in the taxon. This is the first report on genome size for the majority of species in the study. Although genome size could not be used to differentiate taxa in subsections Paniculatae and Phlox, the data provide further insights into cytotype variation of Phlox germplasm useful for plant breeders and systematists. © 2015 American Society for Horticultural Science. All rights reserved.

Zale P.J.,Longwood Gardens Inc. | Robarts D.W.H.,Ornamental Plant Germplasm Center | Robarts D.W.H.,Ohio State University | Jourdan P.,Ornamental Plant Germplasm Center | Jourdan P.,Ohio State University
Scientia Horticulturae | Year: 2016

The eastern North American creeping phlox (Phlox subulata L.) is a widely cultivated flowering groundcover with a history of breeding and selection. Little is known about genome size variation and ploidy of P. subulata and related taxa. Mean holoploid (2C) and monoploid (1Cx) genome sizes and ploidy were analyzed with flow cytometry for a germplasm collection (n = 53) of 11 morphologically similar creeping phlox taxa from natural plant populations, cultivars and hybrids obtained from nursery sources, and the related Microsteris gracilis. Holoploid genome sizes of accessions from natural populations were more variable than cultivated taxa and ranged from 7.47 to 22.86 pg and corresponded to diploid (2n = 2x = 14) tetraploid (2n = 4x = 28), and hexaploid (2n = 6x = 42) levels, but most accessions were diploid and genome size ranged from 7.60 to 8.47 pg. Two tetraploid accessions were discovered, but hexaploids were limited to one population of P. subulata. Most accessions consisted of a single cytotype, but intrapopulation differences in holoploid genome size were found among P. subulata and P. nivalis. The monoploid genome size of M. gracilis differed significantly from all Phlox, supporting separation of the genera. All cultivar accessions were diploid with genome sizes similar to wild diploid P. subulata, however Phlox × procumbens had a mean genome size (8.73 pg) intermediate to parental taxa, P. stolonifera × P. subulata, supporting hybrid origin. Knowledge of cytotype variation in Phlox germplasm will be useful for plant breeders, systematists, and conservationists. © 2016 Elsevier B.V.

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