The dominance of alleles controlling self-incompatibility in Brassica pollen is regulated at the RNA level.
Self-incompatibility (SI) in Brassica is controlled sporophytically by the multiallelic S-locus. The SI phenotype of pollen in an S-heterozygote is determined by the relationship between the two S-haplotypes it carries, and dominant/recessive relationships often are observed between the two S-haplotypes. The S-locus protein 11 (SP11, also known as the S-locus cysteine-rich protein) gene has been cloned from many pollen-dominant S-haplotypes (class I) and shown to encode the pollen S-determinant. However, SP11 from pollen-recessive S-haplotypes (class II) has never been identified by homology-based cloning strategies, and how the dominant/recessive interactions between the two classes occur was not known. We report here the identification and molecular characterization of SP11s from six class II S-haplotypes of B. rapa and B. oleracea. Phylogenetic analysis revealed that the class II SP11s form a distinct group separated from class I SP11s. The promoter sequences and expression patterns of SP11s also were different between the two classes. The mRNA of class II SP11, which was detected predominantly in the anther tapetum in homozygotes, was not detected in the heterozygotes of class I and class II S-haplotypes, suggesting that the dominant/recessive relationships of pollen are regulated at the mRNA level of SP11s.
Shiba
Hiroshi
H
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0101, Japan.
Iwano
Megumi
M
Entani
Tetsuyuki
T
Ishimoto
Kyoko
K
Shimosato
Hiroko
H
Che
Fang-Sik
FS
Satta
Yoko
Y
Ito
Akiko
A
Takada
Yoshinobu
Y
Watanabe
Masao
M
Isogai
Akira
A
Takayama
Seiji
S
D000483:Alleles; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D001937:Brassica / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D005298:Fertility / Q000235:genetics; D015870:Gene Expression; D005799:Genes, Dominant / Q000235:genetics / Q000502:physiology; D005808:Genes, Recessive / Q000235:genetics / Q000502:physiology; D006239:Haplotypes / Q000235:genetics; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011058:Pollen / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins; D017386:Sequence Homology, Amino Acid
D010940:Plant Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C431526:SP11 protein, Brassica