Abstract
We have isolated temperature sensitive mutants of Arabidopsis, msp1 and msp2, which are affected axillary shoot formation. At the restrictive temperature msp mutants do not develop normal rosette leaves but developed a mass of shoot primodia (MSP) as a result of continuous formation of axillary shoot primodia. The MSP was formed in the presence of exogenous cytokinin at the temperature below the restrictive temperature in msp mutants, suggesting the involvement of cytokinin in the MSP formation. In msp mutants, cytokinin responses such as growth and greening of calli, shoots formation from calli and de-etiolation of seedlings did not occur in response to lower levels of cytokinins than in the wild type even at the restrictive temperature. These results suggest that neither the endogenous cytokinin level nor the sensitivity to cytokinins increased in msp mutants at the restrictive temperature.
