Molecular genetic analysis of the candidate gene for MOD, a locus required for self-incompatibility in Brassica rapa.
The MIP-MOD (for MOD-locus associated Major Intrinsic Protein) gene encodes an aquaporin-like product, and has been reported to be a candidate for the MOD gene which is required for the self-incompatibility response in Brassica rapa. In an antisense suppression experiment designed to investigate the role of MIP-MOD, we found that levels of MIP-MOD mRNA in the stigmas of fourteen antisense transgenics, as well as in the self-incompatible cultivar Osome (Osm), were much lower than in the stigmas of the self-incompatible S8 homozygous (S8) strain. Therefore, we analyzed the molecular structure of the MIP-MOD gene in three B. rapa strains: S8, Osm, and the self-compatible var. Yellow Sarson (YS). Nucleotide sequence analysis of the MIP-MOD genes isolated from the three strains revealed that all three encode the same amino acid sequence and that YS and Osm contain the same MIP-MOD allele, designated MIP-MOD(YS). Analysis of other self-incompatible B. rapa strains that are homozygous for the MIP-MOD(YS) allele indicated that high levels of MIP-MOD transcripts are not essential for the self-incompatibility response. Furthermore, a MOD mutant generated by gamma-irradiation was found to contain a wild-type MIP-MOD gene that is expressed at normal levels. These data suggest that MIP-MOD is not MOD itself. We suggest that this gene should be renamed MLM (for MIP gene linked to MOD).
Fukai
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Laboratory of Plant Breeding and Genetics, Graduate School of Agricultural Science, Sendai, Japan.
Nishio
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Nasrallah
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D000483:Alleles; D020346:Aquaporins; D015152:Blotting, Northern; D015139:Blotting, Southern; D001937:Brassica / Q000235:genetics*; D004252:DNA Mutational Analysis; D005091:Exons; D005720:Gamma Rays; D006720:Homozygote; D007473:Ion Channels / Q000235:genetics*; D008957:Models, Genetic; D009154:Mutation; D016376:Oligonucleotides, Antisense; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000378:metabolism; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D014170:Transformation, Genetic
D020346:Aquaporins; D007473:Ion Channels; D016376:Oligonucleotides, Antisense; D010940:Plant Proteins; D012333:RNA, Messenger; C110065:major intrinsic protein, plant