Impairment of Lhca4, a subunit of LHCI, causes high accumulation of chlorophyll and the stay-green phenotype in rice

Impairment of Lhca4, a subunit of LHCI, causes high chlorophyll content and LHCII accumulation in rice, suggesting a novel functional interaction between LHCI and LHCII. Abstract Chlorophyll is an essential molecule for acquiring light energy during photosynthesis. Mutations that result in chlorophy...

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Published in:Journal of experimental botany 2018-02, Vol.69 (5), p.1027-1035
Main Authors: Yamatani, Hiroshi, Kohzuma, Kaori, Nakano, Michiharu, Takami, Tsuneaki, Kato, Yusuke, Hayashi, Yoriko, Monden, Yuki, Okumoto, Yutaka, Abe, Tomoko, Kumamaru, Toshihiro, Tanaka, Ayumi, Sakamoto, Wataru, Kusaba, Makoto
Format: Article
Language:English
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Research Papers
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Summary:Impairment of Lhca4, a subunit of LHCI, causes high chlorophyll content and LHCII accumulation in rice, suggesting a novel functional interaction between LHCI and LHCII. Abstract Chlorophyll is an essential molecule for acquiring light energy during photosynthesis. Mutations that result in chlorophyll retention during leaf senescence are called 'stay-green' mutants. One of the several types of stay-green mutants, Type E, accumulates high levels of chlorophyll in the pre-senescent leaves, resulting in delayed yellowing. We isolated delayed yellowing1-1 (dye1-1), a rice mutant whose yellowing is delayed in the field. dye1-1 accumulated more chlorophyll than the wild-type in the pre-senescent and senescent leaves, but did not retain leaf functionality in the 'senescent green leaves', suggesting that dye1-1 is a Type E stay-green mutant. Positional cloning revealed that DYE1 encodes Lhca4, a subunit of the light-harvesting complex I (LHCI). In dye1-1, amino acid substitution occurs at the location of a highly conserved amino acid residue involved in pigment binding; indeed, a severely impaired structure of the PSI-LHCI super-complex in dye1-1 was observed in a blue native PAGE analysis. Nevertheless, the biomass and carbon assimilation rate of dye1-1 were comparable to those in the wild-type. Interestingly, Lhcb1, a trimeric LHCII protein, was highly accumulated in dye1-1, in the chlorophyll-protein complexes. The high accumulation of LHCII in the LHCI mutant dye1 suggests a novel functional interaction between LHCI and LHCII.
ISSN:0022-0957
1460-2431
DOI:10.1093/jxb/erx468