PT  - JOURNAL ARTICLE
AU  - Woloshuk, C P
AU  - Meulenhoff, J S
AU  - Sela-Buurlage, M
AU  - van den Elzen, P J
AU  - Cornelissen, B J
TI  - Pathogen-induced proteins with inhibitory activity toward Phytophthora infestans.
AID  - 10.1105/tpc.3.6.619
DP  - 1991 Jun 01
TA  - The Plant Cell
PG  - 619--628
VI  - 3
IP  - 6
4099  - http://www.plantcell.org/content/3/6/619.short
4100  - http://www.plantcell.org/content/3/6/619.full
SO  - Plant Cell1991 Jun 01; 3
AB  - A bioassay using Phytophthora infestans was developed to determine whether inhibitory proteins are induced in pathogen-inoculated plants. Using this bioassay, AP24, a 24-kilodalton protein causing lysis of sporangia and growth inhibition of P. infestans, was purified from tobacco plants inoculated with tobacco mosaic virus. Analysis of the N-terminal amino acid sequence identified AP24 as the thaumatin-like protein osmotin II. The sequence was also similar to NP24, the salt-induced protein from tomato. Subsequently, we purified a protein from tomato plants inoculated with P. infestans that had inhibitory activities identical to those of the tobacco AP24. The N-terminal amino acid sequence of this protein was also similar to those of osmotin and NP24. In general, both the tobacco and tomato AP24 caused lysis of sporangia at concentrations greater than 40 nanomolar and severely inhibited hyphal growth at concentrations greater than 400 nanomolar. Because both proteins were induced by pathogen inoculation, we discussed the possible involvement of these proteins as a plant defense mechanism.