Plant hormones function to coordinate plant growth and development. While the
plant hormones, mainly
auxin and
cytokinin, are exogenously added to various plant tissue cultures, their effects on the organogenesis are apparent, but little is known concerning the molecular mechanisms by which they function in cultured cells. Rice, as a model plant in monocots, is also suitable to tissue culture studies. Here, we used four types of regeneration mediums with different relative concentrations of
cytokinin and
auxin for rice callus differentiation, the calli at different differentiation stages were collected for proteomic analysis. 2-dimensional electrophoresis revealed that 213
protein spots significantly differentially expressed during callus differentiation under different
hormone conditions. By using mass spectrometry, 183 differentially expressed
protein spots were identified to match 157 unique
proteins. Most of these differential
proteins were cellular/metabolic process-related
proteins, whose different expression patterns may be correlated with the
cytokinin and
auxin regulation. Several
hormone-related
proteins were prominently featured in differentiated calli as compared with the initiated calli, such as
alpha-amylase isoforms,
mannose-binding
rice lectin, putative
dehydration stress-induced
protein,
cysteine endopeptidase and
cystatin. All these results provide a novel insight into how the two
plant hormones effect the callus differentiation in rice on the proteomic level.