The molecular basis of incomplete dominance at the A locus of CHS-D in the common morning glory, Ipomoea purpurea
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The mutable a flaked (a f ) allele at the A locus of the common morning glory (Ipomoea purpurea) confers incomplete dominance in flower pigmentation and is caused by insertion of the DNA transposon Tip100 into CHS-D, which encodes chalcone synthase and is required for anthocyanin biosynthesis. Levels of CHS-D transcripts, CHS-D protein, and anthocyanin pigment in heterozygous flowers were about half that in homozygous flowers, indicating that dosage-dependent expression of CHS-D is the primary cause of the observed incomplete dominance. This contrasts with the Nivea locus in snapdragon (Antirrhinum majus) in which incomplete dominance is caused by semi-dominant CHS alleles.
KeywordsAnthocyanin pigmentation Chalcone synthase gene Dosage-dependent gene expression Flower variegation Incomplete dominance Ipomoea purpurea
We thank Sharman D. O’Neill for providing the I. nil Actin cDNA, Kazuo Tsugane for helping detect western blot signals, and Atsushi Hoshino and Norio Saito for discussion. This work was supported in part by the Global COE Program and by grants from the Ministry of Education, Science, and Culture of Japan (No. 17207002 to S.I. and No. 18-40089 to Y. J.-H.). Y. Johzuka-Hisatomi was a recipient of an RPD fellowship from the Japan Society for the Promotion of Science (JSPS).
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