WAGs in Root Waving

The search for factors involved in photoregulated development of young seedlings of pea led to the finding of a kinase negatively modulated by light named Pisum sativum Protein Kinase 3 (PsPK3) (Khanna et al. 1999). The completion of the Arabidopsis genome allowed for the identification of PsPK3 orthologs in this organism, named initially AtPK3 and AGC1-11 (Bogre et al. 2003). The function of AtPK3 and AGC1-11 in Arabidopsis was later partly elucidated with the observation that atpk3 agcl-11 double mutants presented enhanced root waving, a finding that resulted in the re-naming of the kinases to WAG1 and WAG2, respectively (Santner and Watson 2006). Santner and Watson further demonstrated that wagl wag2 plants display increased resistance to the root curling-inhibition mediated by NPA, suggesting that the double mutants are defective in auxin-related processes such as PAT. The conclusion that WAG1 and WAG2 participate in the control of PAT is in part corroborated by their amino acid sequence, as they classify in the same AtAGC3 group as PID (Fig. 3). The actual role of the WAGs in PAT and their molecular mechanism of action, however, remains to be elucidated.

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