N. Tsukamoto¹, N. Asakura², Y. Igarashi¹, S. Takumi¹, N. Mori¹, I.Ohtsuka² and C. Nakamura¹ (¹Fac. Agr., Kobe Univ., ²Fac. Engineer., Kanagawa Univ.)

The presence of maternal, paternal and novel paternal-like copies of the mitochondrial nad3-orf156 region in the nucleus-cytoplasm hybrids of tetraploid wheat with A e.squarrosa cytoplasm.

Chromosome 1D of Ae. squarrosa and 1A of timopheevi wheat respectively possess a nuclear gene, Ncc-sqr1D and Ncc-tmp1A, which confers compatibility with the cytoplasm of Ae. squarrosa on the NC hybrids. Mitochondrial DNA organization was studied in three tetraploid NC hybrids with Ae. squarrosa cytoplasm and compared with that in the nucleus and, cytoplasm donors. PCR-RFLP analysis revealed notable polymorphisms in the nad3- orf156 region. The comparative sequence analysis demonstrated the presence of both maternal and paternal copies of this region in the NC hybrids. One novel paternal-like copy was also detected. Our results suggest possible paternal transmission of mtDNA sequence(s) in these NC hybrids.

G.-Z. Wang, Y. Matsuoka and K. Tsunewaki (Fac. Biosci., Fukui Pref Univ.)

Organellar RFLP markers for plasmon distinction in Triticum and Aegilops

To develop molecular markers for plasmon distinction, RFLP of 28 alloplasmic common wheats representing 22 plasmons has been analyzed. Total DNAs were digested with a restriction enzyme (BamHI, HindIII or PstI), and then subjected to hybridization. Two chloroplast and seven mitochondrial probes were used. Twenty plasmon types successfully were distinguished by three probe-enzyme combinations, cox1-Pst I, cox2-Hin dIII and cob- Bam HI. No polymorphism was detected between C and C² plasmons, and between G and G² plasmons despite the differences in phenotypic effects. Close relationship between the plasmons of polyploid wheats and Ae. speltoides was supported by phylogenetic analysis.


Session 2: Structure of wheat chloroplast genome

T. Kojima¹, A. Endo¹, H. Tsuzuki¹, K. Isono² and Y. Ogihara¹ (¹Kihara Inst. Biol. Res., Yokohama City Univ., ²Perkin-Elmer)

Chloroplast genome organization of the region between psbA and psbC in wheat

The nucleotide sequence of wheat chloroplast (cp) DNA with region between psbA and psbC, in which a part of inverted repeat-A (IR-A) is included, has been completed. This region consists of 11,523 base-pairs and contains 12 genes (8 peptide-encoding genes, 3 tRNAs and a putative open reading frame). The 11 genes, except one open reading frame, are identical with the those of rice and maize. The junction point between large single copy (LSC) region and IR-A is determined by comparing with the sequence of wheat cp IR-B. The numbers of nucleotides from this junction point to rps19 (within IR-A) and psbA (LSC) are 50 bp and 90 bp, respectively, and are slightly longer than rice and maize.

Y. Ohnishi, H. Tajiri, Y. Matsuoka and K. Tsunewaki (Fac. Biosci., Fukui Pref. Univ.)

Organization and evolutionary properties of a 21.1kb PstI fragment of the wheat chloroplast DNA with emphasis on RNA polymerase subunit genes.

The entire nucleotide sequence of a 21.1kb PstI fragment of the wheat chloroplast DNA has been determined. This fragment contained 18 genes, including rpoB, rpoC1 and rpoC2 that encode b, b' and b" subunits of RNA polymerase, respectively. Comparison of the wheat genes to those of other plants indicated that they are highly conserved especially among grass species. The following four distinct structural alterations, however, were detected in wheat rpo genes; absence of the intron in rpoC1, deletions in the middle (81bp) and 3'terminal (ca. 30bp) regions of rpoC2 and the presence of an insertional sequence (408bp) in rpoC2.

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