Comparison of Genome Size in Reed Canarygrass (<i>Phalaris arundinacea</i> L.) Exotic and Putative Native Japanese Genotypes by Flow Cytometry

Abstract

Reed canarygrass (Phalaris arundinacea L.) is a cool-season perennial grass widely distributed throughout North America, Europe and Asia. P. arundinacea is currently considered a major invasive plant species in the USA. Despite recent concerns that P. arundinacea has become an invasive plant species in Japan, differences between invasive and native Japanese genotypes remain unclear. We used flow cytometry to clarify genome size differences among 14 populations of putative native Japanese P. arundinacea genotypes and three exotic cultivars. The average genome size of the 14 Japanese populations and the three exotic P. arundinacea differed significantly (P < 0.05) and ranged from 4963.90 to 5166.69 Mbp/C. These results implied that the sampled populations included native Japanese genotypes. These populations may be useful in discriminating between invasive and native Japanese P. arundinacea genotypes. Discipline: Genetic resources Additional key words: invasive plant *Corresponding author: Yukio Akiyama e-mail: akky@affrc.go.jp Received 27 February 2015; accepted 25 March 2015. Introduction Reed canarygrass (Phalaris arundinacea L.) is a coolseason perennial grass widely distributed throughout North America, Europe and Asia (Bews 1929, Hitchcock 1935). Two ploidy levels, tetraploid (2n = 4x = 28) and hexaploid (2n = 6x = 42), have been reported in P. arundinacea (McWilliam and Neal-Smith 1962). The creeping rhizomes of P. arundinacea exhibit vigorous growth, and the species exhibits a marked tolerance to changes in humidity, snow, cold and heat. In addition, because P. arundinacea can be propagated in various ways (seeds, tillers and rhizomes), the species has been an important source of forage in the USA since the nineteenth century, when the European cultivar was introduced, and is also expected to be a promising source of biomass material in the future (Lewandowski et al. 2003, Casler et al. 2009). However, the high propagation of P. arundinacea is also a potential ecological problem, and it is perceived as a major invasive species in the USA (Merigliano & Lesica 1998, Lavergne & Molofsky 2007). It is also thought that the introgression of germplasm from European cultivars into native North American genotypes could account for the increased invasiveness of the species (Merigliano & Lesica 1998). In Japan, P. arundinacea has been used extensively as forage since the latter half of the twentieth century, and, as in America, is currently considered an invasive plant species (Hokkaido Government 2004, 2010). The differences between native and invasive P. arundinacea populations have not yet been investigated, and it is unclear whether genotypes of native Japanese P. arundinacea still exist in the wild, or whether these have been contaminated