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• Quantitative genome size estimation as a tool for plant variety testing

  89-104

  Anita Lepossa

  Mihály Czinkoczky

  Szabolcs Tamás Nagy

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  In plant sciences, flow cytometry (FCM) is the most commonly used method for estimating ploidy levels and genome size. The vast majority of data currently available for more than 12,000 plant species in the Kew Plant Genome Size Database was estimated by using by FCM. However, available data on perennial grass species are scarce.
  We estimated the genome size (2C value) from seedlings of two registered cultivars with known ploidy levels of two native grass species (tall fescue, Festuca arundinacea and red fescue, Festuca rubra) by FCM, with rye (Secale cereale) and pea (Pisum sativum) plant controls. We compared our results to the published data of the Kew Database, and calculated the difference in genome size between the two fescue species.
  Our estimated genome size data were similar to that in the Kew Database. In the case of red fescue, there was a 1.4-fold 2C value-difference between the hexaploid (12.25±0.81 pg DNA) and the octoploid variety (17.12±0.58 pg DNA). However, the genome size of the two tall fescue accessions with different ploidy were almost identical (13.93±0.15 and 13.53±0.14 pg DNA), which questioned the genetic purity of one of the varieties. We calculated a DNA length of 5990 (6n) and 8371 (8n) Mbp for red fescue varieties, and 6810 (6n) Mbp for the tall fescue sample. According to the Kew Database, the average monoploid genome size of tall fescue accessions is higher by 29% compared to red fescue data. In our investigation, we could verify less difference (6–11%) between the two species. FCM method is a useful tool for detecting the inter-species and intra-species variability of the genome size in botanical studies, plant breeding and variety maintenance, but it is also promising for testing the genetic purity of registered varieties.