ISHS Acta Horticulturae 505: VII International Symposium on Rubus and Ribes
USING FLOW CYTOMETRY TO DETERMINE PLOIDY LEVEL IN RUBUS |
| Authors: | R. Meng, C. Finn |
| Keywords: | blackberry, raspberry, breeding, chromosome number |
| Abstract:
Rubus has a wide range of ploidy levels, from diploid to dodecaploid. Knowing the ploidy level of breeding materials is important when planning crosses and to help establish correct identity. The conventional method used to determine ploidy level is chromosome counting under a microscope. This approach is time-consuming, tedious, and requires expertise to ensure accuracy. Nuclear DNA flow cytometry, a potentially more efficient approach, was used to study ploidy levels of representatives of each ploidy from 2x to 12x. Rubus ursinus, which is widely represented in our breeding program and has been reported to have 6x, 8x, 9x, 10x, 11x and 12x forms (Brown, 1943), was extensively tested. Nuclei suspensions were prepared from leaf discs of fresh young leaves following published protocols with modifications. Propidium iodide was used to stain the DNA. Fluorescence increased concurrent with the increase in chromosome number. This protocol also was suitable for genotypes representing 9 different Rubus subgenera. Genotypes of R. ursinus were predominantly 8x or 12x, but 9x and 11x forms were found as well. This technique was effective in differentiating chromosome numbers differing by 1x but was not able to differentiate aneuploids. | |
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