Primary structure and tissue‐specific expression of the pathogenesis‐related protein PR‐1b in potato†

Abstract

Summary The infection of potato (Solanum tuberosum) leaves with the late blight pathogen Phytophthora infestans, or treatment with fungal elicitor, leads to the massive accumulation of pathogenesis-related (PR) proteins in the extracellular leaf space. The most abundant of these proteins was purified to apparent homogeneity and identified as a new, basic member of the PR-1 family of defence proteins, designated PR-1b. Antibodies raised against the protein and a cDNA isolated by differential screening were used to study the temporal and spatial patterns of PR-1b protein and mRNA distribution in healthy and infected potato tissues. PR-1b was present in old leaves and at low levels also in the carpels of flowers. In leaves, strong accumulation of PR-1b mRNA and protein occurred in response to infection by the oomycete pathogen Phytophthora infestans or the bacterial pathogen Pseudomonas syringae pv. maculicola. PR-1b mRNA and protein accumulation was clearly initiated at the infection site, but a delayed and sustained accumulation was also observed in neighbouring, uninfected leaves of potato plants. Tissue- and cell type-specific expression of PR-1b was analysed by immunohistochemical and in situ RNA hybridization techniques. Appreciable amounts of PR-1b protein and mRNA were localized in epidermal cells, guard cells of the stomata, glandular trichomes, crystal idioblasts, and cells of the vascular system of infected leaves. However, no significant differences in the amounts and distribution patterns of PR-1b could be observed between compatible and incompatible interactions of potato and Phytophthora infestans, indicating that PR-1b expression is not involved in determining cultivar/race-specific resistance in potato.

Variation of Herbivore-Induced Volatile Terpenes among Arabidopsis Ecotypes Depends on Allelic Differences and Subcellular Targeting of Two Terpene Synthases, TPS02 and TPS03

“…Interestingly, TPS03 promoter activity was observed in pollen grains and resembles the recently reported expression of a valencene sesquiterpene synthase in the pollen of grape (Vitis vinifera) flowers (Martin et al, 2009). A pattern of constitutive expression in reproductive organs and induced expression in vegetative tissues has also been observed for Arabidopsis geranyllinalool synthase (TPS04/GES; Herde et al, 2008) in the formation of the volatile homoterpene TMTT and has been demonstrated for other genes involved in plant defense (Pollak et al, 1993;Hoegen et al, 2002;Stotz et al, 2009).…”

Enhanced resistance to early blight in transgenic tomato lines expressing heterologous plant defense genes

“…Morel and Vaucheret 2000;Steimer et al 2004). This phenomenon has been reported in various transgenic plants expressing various PR proteins or antimicrobial peptides (Bliffeld et al 1999;Gao et al 2000;Hoegen et al 2002;Li et al 2003).…”

Long-Term Induction of Defense Gene Expression in Potato by Pseudomonas sp. LBUM223 and Streptomyces scabies

“…PR-1 has been vastly used as a marker for the induction of the SA-signaling pathway and exists in both a basic and acidic form, which may differ substantially in their biological activities (40). The potato PR-1b targeted in this study encodes a basic protein, and has previously been shown to be upregulated systemically following infection of potato by P. infestans (21). The PR-2 family is composed of β-1,3-glucanases (40), which in potato are also upregulated systemically by P. infestans (33).…”