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GFS 9/ TT 9 contributes to intracellular membrane trafficking and flavonoid accumulation in A rabidopsis thaliana
Author(s) -
Ichino Takuji,
Fuji Kentaro,
Ueda Haruko,
Takahashi Hideyuki,
Koumoto Yasuko,
Takagi Junpei,
Tamura Kentaro,
Sasaki Ryosuke,
Aoki Koh,
Shimada Tomoo,
HaraNishimura Ikuko
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12637
Subject(s) - intracellular , microbiology and biotechnology , chemistry , flavonoid , biochemistry , biology , antioxidant
Summary Flavonoids are the most important pigments for the coloration of flowers and seeds. In plant cells, flavonoids are synthesized by a multi‐enzyme complex located on the cytosolic surface of the endoplasmic reticulum, and they accumulate in vacuoles. Two non‐exclusive pathways have been proposed to mediate flavonoid transport to vacuoles: the membrane transporter‐mediated pathway and the vesicle trafficking‐mediated pathway. No molecules involved in the vesicle trafficking‐mediated pathway have been identified, however. Here, we show that a membrane trafficking factor, GFS 9, has a role in flavonoid accumulation in the vacuole. We screened a library of Arabidopsis thaliana mutants with defects in vesicle trafficking, and isolated the gfs9 mutant with abnormal pale tan‐colored seeds caused by low flavonoid accumulation levels. gfs9 is allelic to the unidentified transparent testa mutant tt9 . The responsible gene for these phenotypes encodes a previously uncharacterized protein containing a region that is conserved among eukaryotes. GFS 9 is a peripheral membrane protein localized at the Golgi apparatus. GFS 9 deficiency causes several membrane trafficking defects, including the mis‐sorting of vacuolar proteins, vacuole fragmentation, the aggregation of enlarged vesicles, and the proliferation of autophagosome‐like structures. These results suggest that GFS 9 is required for vacuolar development through membrane fusion at vacuoles. Our findings introduce a concept that plants use GFS 9‐mediated membrane trafficking machinery for delivery of not only proteins but also phytochemicals, such as flavonoids, to vacuoles.