Phylogenetic relationships among Fagopyrum species revealed by the nucleotide sequences of the ITS region of the nuclear rRNA gene.

Abstract

The DNA sequences of the internal transcribed spacer (ITS) region of the rRNA gene were determined in 20 taxa of 12 species of Fagopyrum. By comparing the sequence data and constructing phylogenetic trees, the phylogenetic relationships among the Fagopyrum species were established. The sequences of ITS (ITS1 and ITS2) were about 3-7 times more variable than those of the 5.8S subunit of the rRNA gene. The classification of Fagopyrum species based on the DNA sequences of the rRNA gene almost coincides with the classification based on morphology, allozyme variability, and nucleotide sequences of the rbcL-accD region of the chloroplast DNA. A close relationship of F. lineare with the F. statice-F. leptopodum clade was suggested and this was strongly supported by a 68-bp gap in ITS1 found in these three species. A tetraploid F. cymosum from Kathi, India, has two distinct rRNA genes probably on homoeologous chromosomes, and was distinguished from the clade of other diploid/tetraploid F. cymosum with a high bootstrap value. This strengthened the hypothesis of the polyphyletic origin of the tetraploid F. cymosum.

New Fagopyrum species revealed by morphological and molecular analyses.

“…The phylogenetic position of F. pleioramosum in the isozyme tree and the ITS trees is quite different from that in the trees in previous studies based on isozyme variability (Ohnishi and Matsuoka, 1996) and nucleotide sequences of cpDNA and nuclear DNA (Yasui, 1997;Yasui and Ohnishi, 1998). These previous studies have documented a close relationship between F. pleioramosum and F. gracilipes.…”

“…The consistency index (CI; Cluge and Farris, 1969) and the retention index (RI; Farris, 1989) of the tree were CI = 0.571 (excluding autoapomorphies) and RI = 0.712, respectively. Compared with values from other plant systematic studies using ITS nucleotide sequence, these values are lower than some (Yasui, 1997; CI = 0.779 and RI = 0.687: Suh et al, 1993; CI = 0.87) and approximately equal to others (Baldwin, 1993; CI = 0.61 and RI = 0.71: Yuan et al, 1996; CI = 0.587 and RI = 0.606). Thus the level of homoplacious character change is not high in the present ITS sequence data.…”

“…The phylogenetic tree was constructed by the neighborjoining (NJ) method (Saitou and Nei, 1987) using the NEIGHBOR program in PHYLIP version 3.57 package (Felsenstein, 1993). DNA sequences of the seven accessions determined in the present experiment and those of ten accessions of Fagopyrum determined by Yasui (1997) were aligned manually on DNASIS. Nucleotide sequence of F. esculentum ssp.…”

Two distinct groups of natural populations of Fagopyrum urophyllum (Bur. et Franch.) Gross revealed by the nucleotide sequence of a noncoding region in chloroplast DNA

“…Factors for the differentiation between the Kunming group and the Dali group Whatever the cause of the differentiation of the two groups, whether ancestral polymorphism (Ohsako and Ohnishi, 2000) or geographical differentiation of the populations (Yasui and Ohnishi, 1998b), gene flow must have been restricted between them by some factor or factors to maintain the morphological and genetic difference between the two groups over a long period of time. The distribution areas of the Kunming group and the Dali group do not overlap.…”

Production of Haploid Plant of ‘Banpeiyu’ Pummelo [Citrus maxima (Burm.) Merr.] by Pollination with Soft X-Ray-Irradiated Pollen

“…CAPS analysis was performed for the internal transcribed spacer (ITS) region in nuclear ribosomal RNA (rRNA). ITS1 and ITS4 were used as primers (Yasui et al, 1998). For each combination of samples and primers, PCR was carried out twice, and only stable polymorphisms were analyzed.…”