Sequence divergence at chalcone synthase gene in pigmented seed coat soybean mutants of the Inhibitor locus.
Seed coat color in soybeans is determined by the I (Inhibitor) locus. The dominant I allele inhibits seed coat pigmentation, and it has been suggested that there is a correlation between the inhibition of pigmentation by the I allele and chalcone synthase (CHS) gene silencing in the seed coat. Analysis of spontaneous mutations from I to i has shown that these mutations are closely related to the deletion of one of the CHS genes (designated ICHS1). In soybeans with the I/I genotype (cv. Miyagi shirome), a truncated form of the CHS gene (CHS3) is located in an inverse orientation 680 bp upstream of ICHS1, and it was previously suggested that the truncated CHS3- ICHS1 cluster might be involved in CHS gene silencing in the seed coat. In the current study, the truncated CHS3- ICHS1 cluster was compared with the corresponding region of pigmented seed coat mutants in which I had changed to i in Miyagi shirome and in the strain Karikei 584. In the Karikei 584 mutant, the truncated CHS3-ICHS1 cluster was retained and the sequence diverged at a point immediately upstream (32 bp) of this cluster. The sequences upstream of the points of divergence in both mutants almost perfectly matched a part of the registered sequence in a soybean BAC clone containing the soybean cyst nematode resistance-associated gene, and inspection of the sequences suggested that the sequence divergence of the CHS gene in the Karikei 584 and Miyagi shirome mutants was due to an unequal crossing-over via 4-bp or 5-bp short repeats, respectively.
Senda
Mineo
M
Gene Research Center, Hirosaki University, Japan. senda@cc.hirosaki-u.ac.jp
Kasai
Atsushi
A
Yumoto
Setsuzo
S
Akada
Shinji
S
Ishikawa
Ryuji
R
Harada
Takeo
T
Niizeki
Minoru
M
D000217:Acyltransferases / Q000235:genetics*; D001483:Base Sequence; D017353:Gene Deletion; D020868:Gene Silencing / Q000502:physiology; D008969:Molecular Sequence Data; D010858:Pigmentation / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012333:RNA, Messenger / Q000378:metabolism; D012639:Seeds / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013025:Glycine max / Q000235:genetics*
D012333:RNA, Messenger; D000217:Acyltransferases; C020141:flavanone synthetase