Background: Tonoplast intrinsic proteins (TIPs) are widely used as markers for vacuolar
compartments in higher plants. Ten TIP isoforms are encoded by the Arabidopsis genome. For
several isoforms, the tissue and cell specific pattern of expression are not known.
Results: We generated fluorescent protein fusions to the genomic sequences of all members of
the Arabidopsis TIP family whose expression is predicted to occur in root tissues (TIP1;1 and 1;2;
TIP2;1, 2;2 and 2;3; TIP4;1) and expressed these fusions, both individually and in selected pairwise
combinations, in transgenic Arabidopsis. Analysis by confocal microscopy revealed that TIP
distribution varied between different cell layers within the root axis, with extensive co-expression
of some TIPs and more restricted expression patterns for other isoforms. TIP isoforms whose
expression overlapped appeared to localise to the tonoplast of the central vacuole, vacuolar bulbs
and smaller, uncharacterised structures.
Conclusion: We have produced a comprehensive atlas of TIP expression in Arabidopsis roots,
which reveals novel expression patterns for not previously studied TIPs