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Loss of TIP1;1 aquaporin in Arabidopsis leads to cell and plant death
Author(s) -
Ma Shisong,
Quist Tanya M.,
Ulanov Alexander,
Joly Robert,
Bohnert Hans J.
Publication year - 2004
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/j.1365-313x.2004.02265.x
Subject(s) - palisade cell , vacuole , arabidopsis , biology , biochemistry , microbiology and biotechnology , vesicle , aquaporin , botany , cytoplasm , gene , membrane , mutant
Summary Arabidopsis TIP1;1 ( γ TIP) is a member of the tonoplast family of aquaporins (AQP). Using RNA interference (RNA i ) we reduced TIP1;1 to different extent in various lines. When most severely affected, miniature plants died, a phenotype partially complemented by the TIP1;1 homolog Mc MIP‐F. Less severely affected lines produced small plants, early senescence, and showed lesion formation. The relative water content in TIP1;1 RNAi plants was not significantly affected. Global expression profiling suggested a disturbance in carbon metabolism in RNAi lines with upregulated transcripts for functions in carbon acquisition and respiration, vesicle transport, signaling and transcription, and radical oxygen stress. Metabolite profiles showed low glucose, fructose, inositol, and threonic, succinic, fumaric, and malic acids, but sucrose levels were similar to WT. Increased amounts were found for raffinose and several unknown compounds. TIP1;1 RNAi plants also contained high starch and apoplastic carbohydrate increased. A GFP‐TIP1;1 fusion protein indicated tonoplast location in spongy mesophyll cells, and high signal intensity in palisade mesophyll associated with vesicles near plastids. Signals in vascular tissues were strongest not only in vesicle‐like structures but also outlined large vacuoles. Compromised routing of carbohydrate and lack of sucrose provision for cell‐autonomous functions seems to characterize this RNAi phenotype. We suggest a function for TIP1;1 in vesicle‐based metabolite routing through or between pre‐vacuolar compartments and the central vacuole. Phenotype and expression characteristics support a view of TIP1;1 functioning as a marker for vesicles that are targeted to the central vacuole.