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Differential targeting of the tobacco PR‐1 pathogenesis‐related proteins to the extracellular space and vacuoles of crystal idioblasts.
Author(s) -
Dixon D.C.,
Cutt J.R.,
Klessig D.F.
Publication year - 1991
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1991.tb07650.x
Subject(s) - state (computer science) , extracellular , library science , biology , genetics , computer science , algorithm
Several biochemical and localization studies have shown that the acidic isoforms of the tobacco pathogenesis‐related (PR) proteins, PR‐1a, −1b and −1c are secreted to the extracellular spaces of leaves in response to pathogen infection or chemical treatment. Here we report the differential accumulation of these proteins within the vacuoles of specialized cells known as crystal idioblasts. In situ hybridization analysis indicated that crystal idioblasts expressed the PR‐1 genes at the mRNA level and suggested that PR‐1 proteins were synthesized by these cells. Transgenic plants which constitutively express a chimeric gene encoding an acidic PR‐1b isoform also accumulated PR‐1 protein in the extracellular spaces and within crystal idioblast vacuoles. Analysis of mRNA derived from these transgenic plants indicated that expression of the introduced PR‐1b gene was responsible for the accumulation of PR‐1 protein in these two distinct locations. The synthesis and accumulation within crystal idioblasts of PR‐1 proteins, which are secreted by other cell types, indicates that idioblasts sort these proteins in a unique manner. Moreover, this suggests that protein sorting in higher plants may be modulated in a cell specific manner.