cDNA Iibraries were constructed from poly(A)+RNAs that had been isolated from calli 7 days after induction of regeneration on two different media, namely, embryogenesis-inducing medium and organogenesis-inducing medium. Differential screening of the libraries with cDNA probes prepared from unorganized calli and from calli that had been induced to undergo somatic embryogenesis and orga-nogenesis (formation of adventitious shoots) allowed us to identify a CDNA clone, pRSEM1, that was specific to regeneration. Analysis of the temporal accumulation of the mRNA that corresponded to pRSEMI during