Accumulation of extracellular pathogenesis-related proteins in rose leaves following inoculation of in vitro shoots with Diplocarpon rosae

Abstract

Rose shoots var. ‘Iris Gee’ grown in vitro infected with Diplocarpon rosae (blackspot causal agent) led to the accumulation of the pathogenesis-related (PR) proteins in the intercellular space of leaves. Electrophoresis of intercellular fluids by SDS-PAGE and 2D-PAGE revealed that extracellular PR proteins accumulated strongly in infected leaves starting at day 3 after inoculation and increased in abundance with disease development. Sixteen proteins, which were absent or present at a low level in the healthy leaves, have been detected in the intercellular fluid extracted from the infected rose leaves 7 days after inoculation with D. rosae. Western-blot analysis showed that rose PR proteins are serologically related to tobacco PR proteins. Infection of D. rosae resulted not only in strong accumulation of PR-2, PR-3, and PR-5 proteins in the intercellular spaces of rose leaves but also induction of PR-1 protein at a later stage of infection. However, no systemic induction of PR-1 protein was detected in upper newly expanded and uninfected leaves.