Poster: Photosynthesis
Abs #
380: Differential transmission of maternal heteroplasmic chloroplast genome in the uniparental inheritance of Chlamydomonas reinhardtii
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Presenter: |
Nishimura, Yoshiki , yn37@cornell.edu |
Authors | Nishimura, Yoshiki (A) Kikis, Elise (A) Komine, Yutaka (A) Kuroiwa, Tsuneyoshi (B) Stern, David (A) | | Affiliations: |
(A): Boyce Thompson Institute for Plant Research
(B): Graduate School of Science, University of Tokyo
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Chloroplasts and mitochondria carry their own genomes that are transmitted to the progeny following non-Mendelian (maternal) fashion in diverse taxa of plants, ferns, mosses, algae, fungi, and animals. In unicellular algae Chlamydomonas reinhardtii, active digestion of mt- chloroplast (cp) DNA would be the basis for the uniparental inheritance(Sager and Lane, 1972; Kuroiwa et al., 1982; Nishimura et al., 1999). On the other hand, the mt+ cp genome is thought to be transmitted without any restriction. Here we show a novel exception for this widely accepted idea. The chloroplast genome of spa 19 strain is heterogeneous and constitute of two different species of cpDNA molecules. This strain was obtained unexpectedly as one of the photosynthetic revertants from non-photosynthetic chloroplast transformant delta26pAtE strain (Komine et al., 2002). The mRNA of atpB gene of the delta26pAtE strain is unstable due to the artificially added poly(A) sequence and this results in the defective photosynthesis. In spa19 strain, it was found that the unstability of atpB mRNA is overcome by a novel cpDNA molecules which was designated as PS+ genome. But in the sexual cross, the PS+ genome was transmitted poorly to the progeny even when they were mt+ origin, whereas the original (PS-) genome is transmitted faithfully. Presently, preliminary data indicates that the differential transmission of the two heteroplasmic cp genomes might be due to their difference in replication rate in germinating zygotes. This replicational regulation of cp genomes might function as one of the mechanism for the quality control of cp genomes.
