RRC ID 703
Author Nomura T, Ishihara A, Yanagita RC, Endo TR, Iwamura H.
Title Three genomes differentially contribute to the biosynthesis of benzoxazinones in hexaploid wheat.
Journal Proc Natl Acad Sci U S A
Abstract Hexaploid wheat (Triticum aestivum) accumulates benzoxazinones (Bxs) as defensive compounds. Previously, we found that five Bx biosynthetic genes, TaBx1-TaBx5, are located on each of the three genomes (A, B, and D) of hexaploid wheat. In this study, we isolated three homoeologous cDNAs of each TaBx gene to estimate the contribution of individual homoeologous TaBx genes to the biosynthesis of Bxs in hexaploid wheat. We analyzed their transcript levels by homoeolog- or genome-specific quantitative RT-PCR and the catalytic properties of their translation products by kinetic analyses using recombinant TaBX enzymes. The three homoeologs were transcribed differentially, and the ratio of the individual homoeologous transcripts to total homoeologous transcripts also varied with the tissue, i.e., shoots or roots, as well as with the developmental stage. Moreover, the translation products of the three homoeologs had different catalytic properties. Some TaBx homoeologs were efficiently transcribed, but the translation products showed only weak enzymatic activities, which inferred their weak contribution to Bx biosynthesis. Considering the transcript levels and the catalytic properties collectively, we concluded that the homoeologs on the B genome generally contributed the most to the Bx biosynthesis in hexaploid wheat, especially in shoots. In tetraploid wheat and the three diploid progenitors of hexaploid wheat, the respective transcript levels of the TaBx homoeologs were similar in ratio to those observed in hexaploid wheat. This result indicates that the genomic bias in the transcription of the TaBx genes in hexaploid wheat originated in the diploid progenitors and has been retained through the polyploidization.
Volume 102(45)
Pages 16490-5
Published 2005-11-8
DOI 10.1073/pnas.0505156102
PII 0505156102
PMID 16260753
PMC PMC1283429
MeSH Base Sequence Benzoxazines / metabolism* Catalysis Gene Expression Regulation, Plant Genome, Plant* Molecular Sequence Data Polyploidy RNA, Messenger / analysis Triticum / genetics* Triticum / metabolism
IF 9.412
Times Cited 85
Wheat ditelosomic (DT) stocks LPGKU1227 LPGKU1217 KU-199-6 KU-5727A? KU-20-9