Reference "Use of alternate splice sites in granule-bound starch synthase mRNA from low-amylose rice varieties"

Reference ID

986

Title

Use of alternate splice sites in granule-bound starch synthase mRNA from low-amylose rice varieties

Source

Plant molecular biology, 1998, vol. 38, pp. 407-415

Authors (7)

Frances-H	Bligh-J
Larkin-P-D	Roach-P-S
Jones-C-A	Fu-H
Park-W-D

Abstract

The rice Waxy gene encodes a granule-bound starch synthase (GBSS) necessary for
the synthesis of amylose in endosperm tissue. We have previously shown that a
CT microsatellite near the transcriptional start site of the GBSS gene can
distinguish 7 alleles that accounted for more than 80% of the variation in
apparent amylose content in an extended pedigree of 89 US rice cultivars (Oryza
sativa L.). Furthermore, all the cultivars with 18% or less amylose were shown
to have the sequence AGTTATA at the putative leader intron 5' splice site,
while all cultivars with a higher proportion of amylose had AGGTATA. Here we
demonstrate that this single-base mutation reduces the efficiency of GBSS pre-
mRNA processing and results in alternate splicing at three cryptic sites. The
predominant 5' splice site in CT18 low-amylose varieties is 93 bp upstream of
the splice site used in intermediate and high amylose varieties and is
immediately 5' to the CT microsatellite that we previously demonstrated to be
tightly correlated with amylose content. Use of the leader intron 5' splice
site at either -93 or -1 in conjunction with the predominant 3' splice site
results in formation of a small open reading frame 38 bp upstream of the normal
ATG and out of frame with it. This open reading frame is not produced when any
of the 5' leader intron splice sites are used in conjunction with an alternate
3' splice site five bases further downstream which was observed in all rice
varieties tested.