Evidence that generation of inositol 1,4,5-trisphosphate and hydrolysis of phosphatidylinositol 4,5-biphosphate are rapid responses following addition of fungal elicitor which induces phytoalexin synthesis in lucerine ( Medicago sativea) suspension culture cells

• Published in: Cellular signalling Vol. 5; no. 3; pp. 345 - 356
• Main Authors: Walton, Terence J., Cooke, Carol J., Newton, Russell P., Smith, Christopher J.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 1993
• Subjects: 5-triphosphate; inositol 1; lucerne; medicago sativa; phosphoinositide hydrolysis; Phytoalexin elicitation; plant cell signalling; plant-pathogen interaction; InsP; InsP 3; PtdIns(4,5)P 2; InsP 2; Phytoalexin elicitation; plant cell signalling; PtdInsP; PtdEth; Ins(1,4,5)P 3; medicago sativa; phosphoinositide hydrolysis; TCA; 4; 5-triphosphate; lucerne; Ins(4,5)P 2; PtdIns; inositol 1; plant-pathogen interaction; PtdCho; RTLC
• ISSN: 0898-6568; 1873-3913
• DOI: 10.1016/0898-6568(93)90026-I

Treatment of lucerne suspension culture cells with glycoprotein elicitor from the phytopathogenic fungus Verticillium albo-atrum R & B triggers Ca 2+-mediated induction of antimicrobial secondary metabolites termed phytoalexins. The present study investigated the possible role of polyphosphoinositide signal transduction in phytoalexin elicitation. Within 1 min of addition of elicitor to lucerne suspension culture cells we found a 100–160% (15–25 pmol/g fresh wt) increase in the level of compound with chromatographic and electrophoretic properties expected for an inositol trisphosphate (InsP 3) and which was strongly bound by an inositol 1,4,5-triphosphate (Ins(1,4,5)P 3)-specific binding protein; after 3 min the level of this compound had fallen below that observed prior to elicitor challenge. In 32P-prelabelled cells, the relative proportion of radioactivity which cochromatographed with phosphatidylinositol 4,5-biphosphate (PtdIns(4,5)P 2) was found to have decreased by 48% 1 min after elicitor addition and that rapid depletion of membrane lipid radioactivity was specific to this lipid fraction. The rapid, transient increase in level of Ins(1,4,5)P 3 and concomitant fall in PtdIns(4,5)P 2 suggests that Ins(1,4,5)P 3 generated by hydrolysis of PtdIns(4,5)P 2 may provide a Ca 2+-mobilizing signal in phytoalexin elicitation in lucerne.