Identification of rice root proteins regulated by gibberellin using proteome analysis

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Abstract
Gibberellin (GA) promoted rice (Oryza sativa L.) root elongation in a concentration‐dependent manner with roots grown in 0.1 µm GA3 being 13.8% longer than controls. On the other hand, the roots of Tan‐ginbozu, a semi‐dwarf cultivar were 69.8% shorter in comparison with Nipponbare, a normal cultivar. Treatments with 10 µm uniconazole‐P and 10 µm abscisic acid (ABA) caused decreases in root length in Tan‐ginbozu by 44.6 and 79.2%, respectively. To investigate how GA influences rice root growth, proteome analysis techniques were applied. Extracted proteins were separated by two‐dimensional polyacrylamide gel electrophoresis and analysed using an automated protein sequencer and mass spectrometer. Sixteen proteins show differences in accumulation levels as a result of treatment with GA3, uniconazole‐P and ABA treatment and/or the difference between the semi‐dwarf cultivar, Tan‐ginbozu, and normal cultivars. Among these proteins, fructose‐bisphosphate aldolase (EC 4.1.2.13) increased in roots treated with GA3, occurred in low levels in Tan‐ginbozu roots, and decreased in roots treated with uniconazole‐P or ABA. Moreover, roots from seedlings grown in 100 µm glucose were 9.1% longer than controls. These results indicate that increases in fructose‐bisphosphate aldolase activity stimulate the glycolytic pathway and may play an important role in the GA‐induced growth of roots.