THE PLANT CELL, Vol 1, Issue 9 913-924, Copyright © 1989 by American Society of Plant Biologists
Analysis of Avenin Proteins and the Expression of Their mRNAs in Developing Oat Seeds
R. S. Chesnut, M. A. Shotwell, S. K. Boyer and B. A. Larkins
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
We have isolated and characterized cDNA clones encoding avenins, the
prolamine storage proteins of oat seeds. Sequence analysis shows that
avenins are a related group of polypeptides and that their mRNAs differ
from each other by point mutations and small insertions and deletions.
Avenin proteins have structural homology to the [alpha]/[beta]-gliadins and
[gamma]-gliadins of wheat, the B-hordeins of barley, and the
[gamma]-secalins of rye. Hybridization analysis of DNA from various
diploid, tetraploid, and hexaploid oat species shows that the oat genome
contains more globulin storage protein genes than avenin genes and that
some restriction fragments containing these genes are conserved between
species with common genomes. We estimate that there are 25 avenin genes and
50 globulin genes per haploid genome in Avena sativa and similar ratios of
globulin to avenin genes in other Avena species. Avenin and globulin
polypeptides begin to accumulate between 4 days and 6 days after anthesis.
Messenger RNAs encoding avenin and globulin proteins become abundant 4 days
after anthesis and reach peak concentrations at 8 days after anthesis.
Avenin mRNAs are present in somewhat greater molar amounts than globulin
mRNAs beginning at 4 days after anthesis. Because there is considerably
more globulin than avenin in the mature oat seed, the expression of
globulin and avenin genes may be regulated both transcriptionally and
post-transcriptionally.
