Genetic variations in Lycoris radiata var. radiata in Japan

The genetic variations of Lycoris radiata var. radiata, a completely sterile triploid from Japan, were examined by comparing the nucleotide sequences of genomic DNA regions in 11 triploid strains sampled from Japan and four triploid strains sampled from China, and in two diploid strains of Lycoris radiata var. pumila, which is endemic to China and fertile. For this purpose, two genes were analyzed, the lectin gene in the nuclear genome and the maturase gene in the chloroplast genome. A clear genetic constancy was observed in their DNA nucleotide sequences. For both genes, completely identical nucleotide sequences were detected in the 11 Japanese and four Chinese triploid strains and also between the two Chinese diploid strains. However, some genetic variations were observed between the Japanese and Chinese triploid strains, and between the triploid and diploid strains. These results are consistent with the findings obtained from previous chromosome karyotype analyses and allozyme analyses. In addition, in our preliminary FISH analysis of the physical mapping of the rRNA gene family, the 18S-5.8S-26S rRNA and 5S rRNA loci were localized on six and four chromosomes, respectively. Regarding the 18S-5.8S-26S rRNA loci, two were associated with two SAT chromosomes. The remaining four were distinguished by having no secondary constriction. Localization of 5S rRNA loci to chromosome spreads revealed three sites on the proximal part of the long arm of three acrocentric chromosomes and one site on the distal part of the long arm of the SAT chromosome; the latter site was juxtaposed to the 18S-5.8S-26S rRNA loci. These findings indicate that L. radiata var. radiata is not a typical autotriploid. The present paper discusses the possible origin of L. radiata var. radiata from a diploid variety of L. radiata var. pumila, based on the molecular cytogenetic analysis and DNA sequence analysis.