Altered ARA2 (RABA1a) expression in Arabidopsis reveals the involvement of a Rab/YPT family member in auxin-mediated responses.

Ras super family proteins serve as molecular switches regulating many different cellular processes. However, given the large number of family members, sequence information has provided little insight into the function of individual proteins. This study examined phenotypic alterations in an Arabidopsis ara2 mutant, in which a Ras super family member-encoding gene is disrupted by a T-DNA insertion.

Ectopic expression of Expansin3 or Expansinbeta1 causes enhanced hormone and salt stress sensitivity in Arabidopsis.

Expansins are cell wall loosening proteins that appear to permit the microfibril matrix network to slide in growing plant cell walls, thereby enabling the wall to expand. To scrutinize possible impacts on plant growth and development when expansins are over-expressed, we characterized phenotypic alterations of the transgenic plants that constitutively expressed AtEXP3 or AtEXP-beta1 under control of 35S-CaMV promoter. Our results suggest that both AtEXP3-OX and AtXPbeta1-OX are very sensitive to salt stress.

Arabidopsis hot2 encodes an endochitinase-like protein that is essential for tolerance to heat, salt and drought stresses.

The Arabidopsis hot2 mutant was originally identified based on its lack of thermotolerance, but pleiotropic abnormal phenotypes are also exhibited under normal conditions, including semi-dwarfism, ethylene overproduction and aberrant cell shape with incomplete cell walls. Here we present additional characterization of the hot2 mutant, and the map-based cloning of HOT2. Mutants of hot2 had an aberrant tolerance to salt and drought stresses, and accumulated high levels of Na(+) in cells under either normal or NaCl stress conditions.