Comparison of the genome size, endoreduplication, and ISSR marker polymorphism in eight Lotus (Fabaceae) species

Abstract

Several species within the genusLotusare important forage crops, and many are endangered or rare. Despite the high geneticdiversity of the genus, identification ofLotusspecies is problematic because of the limited number of reliable morphological markers. Insearch of a quick, inexpensive, and steady method for species identification, genome size and cell cycle/endoreduplication intensity of14 accessions belonging to eightLotusspecies were estimated by flow cytometry. ISSR-PCR was also applied to find sensitive molecularmarkers for genetic diversity estimation. Genome size estimation revealed thatLotusspecies possess very small genomes and thischaracteristic enables the identification of five out of eight species. However, a flow cytometric study of cell ploidy/endopolyploidy inseeds and seedlings enabled us also to distinguish the remaining species. Thus, it is proposed here that combined flow cytometric analyses(the estimation of genome size and cell cycle/endoreduplication pattern) can be applied for screening ofLotusspecies. Nonetheless, ISSRmarkers provided a more precise identification of studied accessions, including detection of genetic diversity within a species. Mostof the tested primers revealed polymorphism between species, and three primers, (GACA) 4 , (CA) 7 G, and (CTC) 4 RC, also revealedpolymorphism between accessions within a species. The ISSR markers revealed high polymorphism between eightLotusspecies andlow intraspecific variation between accessions within the same species ( L. maritimusandL. uliginosus ).