Genetic Analysis of Putative Triploid Miscanthus Hybrids and Tetraploid M. sacchariflorus Collected from Sympatric Populations of Kushima, Japan

Abstract

Miscanthus ×giganteus, which is a triploid hybrid between tetraploid M. sacchariflorus and diploid M. sinensis, has considerable potential as a bioenergy crop. Currently only one genotype is widely cultivated, increasing its vulnerability to diseases during production. Finding new hybrids is important to broaden genetic resources of M. ×giganteus. Three putative triploid hybrids were discovered in sympatric population of tetraploid M. sacchariflorus and diploid M. sinensis in Kushima, Japan. The hybrid nature of the triploids was determined by morphological analysis and sequencing the ribosomal DNA internal transcribed spacer region. The triploids had awns on their florets, which is a common characteristic of diploid M. sinensis, and sheath hairs, which is typical of tetraploid M. sacchariflorus. All triploids showed heterozygosity in their ribosomal DNA internal transcribed spacer sequences. Based on these results, it is confirmed that the triploids are hybrids and novel genotypes of M. ×giganteus. Natural crossing between tetraploid M. sacchariflorus × diploid M. sinensis may also lead to the production of tetraploid hybrids. ITS analysis of tetraploid plants showed that one maternal parent of the triploid hybrids, K-Ogi-1 had heterozygous ITS, which was different to the other analyzed tetraploid M. sacchariflorus. Thus, K-Ogi-1 was likely of hybrid origin. These tetraploid hybrids can also be utilized as parents in M. ×giganteus breeding. Since all hybrids identified in this study had tetraploid M. sacchariflorus as maternal parents, collecting and analyzing seeds from tetraploid M. sacchariflorus in sympatric areas could be an effective strategy to identify natural Miscanthus hybrids that can be used as bioenergy crops.

A detailed gene expression study of the Miscanthusgenus reveals changes in the transcriptome associated with the rejuvenation of spring rhizomes

“…The grass is an obligate outcrosser with a large, highly repetitive 2.5 Gbp (giga base pairs) genome that is distributed across nineteen chromosomes [3, 4]. Natural hybridization events between the two most predominant Miscanthus species, M. sinensis and M. sacchariflorus , have been reported [5, 6]. Ribosomal DNA evidence suggests that the large statured, cold tolerant, sterile triploid hybrid M. × giganteus (3 n  = 57) is the result of a natural hybridization event between a diploid M. sinensis (2 n  = 38) and a tetraploid M. sacchariflorus (4 n  = 76) [2, 4, 7].…”

DNA markers for identifying interspecific hybrids between Miscanthus sacchariflorus and Miscanthus sinensis

“…However, in this study, these two accessions were treated as M. × ogiformis because they have awns on their florets (Dwiyanti et al . ). For screening the primer sets to generate species‐specific fragments, six accessions each from M. sacchariflorus (‘Teshio,’ ‘Akan,’ ‘Hitsujigaoka‐1,’ ‘Morioka,’ ‘Miyakonojyo’ and ‘Uchinoura’) and from M .…”

Miscanthus

“…The plants were confirmed to have 57 chromosomes. Through internal transcribed spacer (ITS) sequence and chloroplast DNA analysis, the plants were confirmed as hybrids between M. sinensis and M. sacchariflorus [33]. One of these three hybrids showed the good biomass potential in Sapporo (unpublished).…”

“…Recently, Nishiwaki et al [32] investigated sympatric populations of M. sinensis and M. sacchariflorus to locate natural hybrids between M. sinensis and M. sacchariflorus. Three natural hybrids were successfully identified and subsequently verified by morphological analysis and sequencing of ribosomal DNA internal transcribed spacer regions [33].…”