Mutations in wheat starch synthase II genes and PCR-based selection of a SGP-1 null line.
Wheat (Triticum aestivum L.) starch synthase II, which is also known as starch granule protein 1 (SGP-1), plays a major role in endosperm starch synthesis. The three SGP-1 proteins, SGP-A1, B1 and D1, are produced by three homoeologous SSII genes, wSSII-A, B, and D. Lines carrying null alleles for each SGP-1 protein have previously been identified. In this report, the mutations occurring in each wSSII gene were characterized, and PCR-based DNA markers capable of detecting the mutations were developed. In the null wSSII-A allele, a 289 bp deletion accompanied by 8 bp of filler DNA was present near the initiation codon. A 175 bp insertion occurred in exon 8 of the null wSSII-B allele. The insertion represented a recently discovered miniature inverted-repeat transposable element (MITE) named Hikkoshi that was first found in a wheat waxy gene. A 63 bp deletion was found at the region surrounding the junction of the fifth exon and intron of the null wSSII-D allele. Based on this information, we designed primer sets to enable us to conduct allele-specific amplifications for each locus. The applicability of these primer sets for breeding programs was demonstrated by reconstructing a line lacking all three SGP-1 proteins using marker-assisted selection. These markers will also be useful in breeding programs aimed at obtaining partial mutants missing one or two SGP-1 proteins.
Shimbata
T
T
Central Laboratory, Nippon Flour Mills Co. Ltd., 5-1-3 Midorigaoka, Atsugi, Kanagawa, Japan. tnaka@affrc.go.jp
Nakamura
T
T
Vrinten
P
P
Saito
M
M
Yonemaru
J
J
Seto
Y
Y
Yasuda
H
H
D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D001947:Breeding / Q000379:methods; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D040461:Gene Components; D005819:Genetic Markers / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013214:Starch Synthase / Q000235:genetics*; D014908:Triticum / Q000235:genetics*
D017931:DNA Primers; D005819:Genetic Markers; D010940:Plant Proteins; C111377:starch synthase II; D013214:Starch Synthase