Reference "Characterization of an alpha-amylase multigene cluster in rice"

Reference ID

4298

Title

Characterization of an alpha-amylase multigene cluster in rice

Source

Plant molecular biology, 1991, vol. 16, pp. 579-591

Authors (4)

Sutliff-T-D	Huang-N
Litts-J-C	Rodriguez-R-L

Abstract

Rice genomic clones containing eight different alpha-amylase genes have been
previously classified into five groups based on DNA hybridization studies and
restriction site mapping. This report describes the clustering of three Group 3
genes (RAmy3A, RAmy3B and RAmy3C) within 28 kb of genomic DNA. The genes are
separated from each other by about 5 kb and transcribed in the same direction.
At the protein level, RAmy3B and RAmy3C are 95% homologous while each is 78%
homologous to RAmy3A. All three genes have relatively small introns in the first
and third positions. RAmy3A; however, has an additional 409 bp intron in the
second intron insertion site. Nucleotide sequence comparisons of the coding and
3' flanking regions suggest that clustering of the RAmy3 genes occurred by gene
duplication resulting from unequal crossing-over at repetitive sequences. A
comparison of the 5' flanking regions revealed several sequences that may be
involved in transcription. Expression of RAmy3B/C first appears in the
germinating seed after two days and at a higher level after four days.
Quantitative primer extension analysis indicates that RAmy3B and RAmy3C
contribute 25% and 75%, respectively, of the transcripts from this cluster at
four days of germination. No primer extension band specific to RAmy3A
transcripts could be detected at this time point. However, RAmy3A PCR products
could be amplified from RNA isolated from embryo-derived callus tissue.