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ARS Home » Pacific West Area » Corvallis, Oregon » National Clonal Germplasm Repository » Research » Publications at this Location » Publication #316128
Title: Rubus ploidy assessment

Author
item Hummer, Kim
item Bassil, Nahla
item ALICE, LARRY - Western Kentucky University

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2015
Publication Date: 5/19/2016
Citation: Hummer, K.E., Bassil, N.V., Alice, L. 2016. Rubus ploidy assessment. Acta Horticulturae. 1133:81-88. doi: 10.17660/ActaHortic.2016.1133.13.

Interpretive Summary: The U.S. Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository (NCGR), Corvallis, Oregon, maintains the U.S. national collection for raspberry and blackberry germplasm. The NCGR genebank includes more than 2,035 accessions, with representatives of 174 crop wild relatives and cultivated forms from 57 countries. The primary collection of these clone and their wild relatives are maintained in containers in greenhouses and screenhouses. The main crops of global economic importance include raspberries, blackberries, and hybrids between them. Breeders wish to expand gene accessibility not only within these subgenera to include representatives of the rich diversity and variability present in the genus. The objective of this research was to evaluate the amount of chromosomes of recently acquired accessions received into the NCGR collection. This number was assessed through flow cytometry using cell preparations from leaf samples. The gametic number for Rubus is x = 7. We observed species from 7 subgenera. Some had very divers amounts of chromosomes. These plants have indergone whole genome duplication during evolutionary history. . Some wild blackberries, originally introduced from Europe but naturalized in Oregon and California, had the usual 4 sets of chromosomes; others unexpectedly had much higher numbers, like 6, 7, or 8 sets of chromosomes.. This indicated that these non-native plants had hybridized with native species. The two species of some species from New Zealand had very small sizes of chromosomes, for having 4 sets of them. Further study of other species in this group is under research.

Technical Abstract: The U.S. Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository (NCGR), Corvallis, Oregon, maintains the national collection for Rubus germplasm. The NCGR genebank includes more than 2,035 accessions, with representatives of 174 Rubus taxa from 57 countries. The primary collection of clonal Rubus and their wild relatives are maintained as plants in containers in greenhouses and screenhouses. The main crops of global economic importance include red raspberries (R. idaeus), subgenus Idaeobatus, and blackberries (subgenus Rubus) and hybrids between them. Breeders wish to expand gene accessibility outside these subgenera to include representatives of the rich diversity and variability present in the genus. The objective of this research was to evaluate ploidy levels of recently acquired Rubus accessions added to the NCGR collection. Ploidy was assessed through flow cytometry using cell preparations from leaf samples. The gametic number for Rubus is x = 7. We evaluated Rubus species from seven subgenera. Subgenus Cylactis had 2x and 4x members; Idaeobatus had 2x, 3x, and 4x types. The blackberry accessions, subgenus Rubus, were the most diverse, having 2x, 4x, 5x, 6x, 7x, 8x, 10x, and 12x cytotypes. Some R. armeniacus samples, introduced from Europe but naturalized in Oregon and California, were 4x; others unexpectedly had much higher ploidy levels. This suggests that R. armeniacus has hybridized with native species of higher ploidy. The two species of Micranthobatus examined were 4x but had very small genomes. Further study of other species in this subgenus is warranted.