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GrainGenes Reference Report: GNM-38-919

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Reference	GNM-38-919
Title	Variation of nitrate reductase genes in selected grass species
Journal	Genome
Year	1995
Volume	38
Pages	919-927
Author	Zhou J Kilian A Warner R Kleinhofs A
Abstract	In order to study the variation of nitrate reductase (NR) genes among grass species, gene number, intron size and number, and the heme-hinge fragment sequence of 25 grass species were compared Genomic DNA cut with six restriction enzymes and hybridized with the barley NAD(P)H and NADH NR gene probes revealed a single NAD(P)H NR gene copy and two or more NADH NR gene copies per haploid genome in most of the species examined Major exceptions were Hordeum vulgare, H vulgare ssp spontaneum, and Avena strigosa, which appeared to have a single NADH NR gene copy The NADH NR gene intron number and lengths were examined by polymerase chain reaction amplification Introns I and III appeared to be absent in at least one of the NADH NR genes in the grass species, while intron II varied from 0.8 to 2.4 kilobases in length. The NADH NR gene heme-hinge regions were amplified and sequenced. The estimated average overall nucleotide substitution rate in the sequenced region was 7.8 X 10(-10) substitutions/site per year. The synonymous substitution rate was 2.11 X 10(-9) substitutions/synonymous site per year and the nonsynonymous substitution rate was 4.10 X 10(-10) substitutions/nonsynonymous site per year. Phylogenetic analyses showed that all of the wild Hordeum species examined clustered in a group separate from H. vulgare and H. vulgare ssp. spontaneum.
Keyword	[ Hide all but 1 of 16 ] avena nuda genetic variation gramineae hordeum hordeum spontaneum hordeum vulgare introns molecular sequence data multiple genes nitrate-reductase nucleotide sequence nucleotide-substitution phylogeny southern-blotting structural genes wild-plants

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