ß-D-Glucan nanoparticle pre-treatment induce resistance against Pythium aphanidermatum infection in turmeric.

In vitro experiments were carried out to test the efficacy of GNP (ß-D-glucan nanoparticle prepared from mycelium of Pythium aphanidermatum) against rhizome rot disease of turmeric (Curcuma longa L.) caused by P. aphanidermatum. GNP (0.1%, w/v) was applied to rhizome prior to inoculation with P. aphanidermatum (0 h, 24 h). Cell death, activities of defense enzymes such as peroxidase, polyphenol oxidase, protease inhibitor and ß-1,3 glucanase were monitored. Prior application of GNP (24 h) to turmeric rhizome effectively controls P. aphanidermatum infection. The increase in defense enzyme activities occurred more rapidly and was enhanced in P. aphanidermatum infected rhizomes that were pre-treated with GNP. Pre-treatment also induced new isoforms of defense enzymes. Increased activities of defense enzymes suggest that they play a key role in restricting the development of disease symptoms in the rhizomes as evidenced by a reduction in cell death. The results demonstrated that GNP can be used as a potential agent for control of rhizome rot disease.

Pythium aphanidermatum: culture, cell-wall composition, and isolation and structure of antitumour storage and solubilised cell-wall (1----3),(1----6)-beta-D-glucans.

Under optimal conditions for the culture of the fungus Phytium aphanidermatum, no polysaccharides were excreted into the medium. The mycelium contained up to 38% of a slightly branched, storage (1----3),(1----6)-beta-D-glucan with a MW of 20,000. The cell-wall polysaccharides of the mycelium comprised 18% of cellulose and 82% of (1----3),(1----6)-beta-D-glucans. Of the non-cellulosic glucans, approximately 33% could be solubilised by extraction with water at 121 degrees, and they had a MW of 10,000, were highly branched, and contained 6% of (1----6) linkages. Treatment of the cell wall with 0.1 M trifluoroacetic acid released approximately 50% of the non-cellulosic glucans. The acid-soluble cell-wall (1----3),-(1----6)-beta-D-glucans of lower MW (6000) were still highly branched and contained 14% of (1----6) and 8% of (1----4) linkages. The storage glucan and the hot-water-soluble cell-wall glucan exhibited strong activity against the Sarcoma 180 in CD-1 mice, whereas the acid-soluble cell-wall glucans were inactive. The hot-water-soluble cell-wall glucan was also active against the DBA/2-MC.SC-1 fibrosarcoma in DBA/2 mice.