Growth responses and lignin production in cell suspensions of Pinus elliottii ‘elicited’ by chitin, chitosan or mycelium of Cronartium quercum f.sp. fusiforme

Abstract

Incubation of suspension-cultured slash pine (Pinus elliotti Engelm.) cells with living mycelial plugs or homogenized, washed and autoclaved mycelium of Cronartium quercum f.sp. fusiforme led to rapid clouding of the medium and visible inhibition of cell growth with only a slight increase in cell mortality. Purified chitin elicited similar changes in cloudiness and growth. Chitin treatment concentrations of up to 1 mg ml^-1 showed only slight changes in viability over several days (as with the mycelium and mycelial extract). In contrast, chitosan concentrations of as low as 60 μgml^-1 showed cell mortality and browning, with a complete ‘hypersensitive’ response and over 90% cell death occurring within 48 h at between 180 and 270 μ ml^-1 chitosan amendment. Phloroglucinol staining showed the presence of lignin-like compounds in the medium and lignin-like compounds were elevated in the cell walls of the chitin, chitosan and mycelium elicited suspension cultures as compared to controls.