An in planta induced gene of Phytophthora infestans codes for ubiquitin

Abstract

An in planta induced gene of Phytophthora infestans (the causal organism of potato late blight) was isolated from a genomic library by differential hybridization using labelled cDNA derived from poly(A)⁺ RNA of P. infestans grown in vitro and labelled cDNA made from potato-P, infestans interaction poly(A)⁺ RNA as probes. Sequence analysis showed that the gene codes for ubiquitin, a highly conserved protein which plays an important role in several cellular processes. The structure of the polyubiquitin gene is consistent with the stucture of other known polyubiquitin genes. Northern and Southern blot analyses revealed that the polyubiquitin gene is a member of a multigene family of which all genes show induced expression in planta.