Submitted to: Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop-The Peanut Foundation
Publication Type: Abstract Only
Publication Acceptance Date: September 10, 2004
Publication Date: October 1, 2004
Citation: Liang, X.Q., Guo, B., Holbrook, Jr., C.C., Lynch, R.E. 2004. Peanut storage protein, conglutin-like protein, has B-1,3-glucanase activity and is induced by colonization with Aspergillus flavus [abstract]. In: Proceedings of the 2004 Fungal Genomics and Aflatoxin/Fumonisin Elimination Workshop, October 25-28, 2004, Sacramento, CA. Technical Abstract: Infection of peanut (Arachis hypogaea L.) seeds by Aspergillus flavus and A. parasiticus is a serious problem of contamination of the seeds with aflatoxins. Breeding the resistant cultivars would be an effective approach to eliminate aflatoxin accumulation. The objective of this study was to investigate the expression of the PR protein ß-1,3-glucanase and the isoform patterns in peanut seeds inoculated with A. flavus. Peanut genotypes, GT-YY9 and GT-YY20 (resistant to Aspergillus flavus infection), and Georgia Green and A100 (susceptible to A. flavus infection), were used in this study. The activities of ß-1,3-glucanase were similar in the uninfected seeds of all genotypes, but increased significantly in the resistant genotypes after inoculation in comparison with the susceptible genotypes. An in-gel (native PAGE) enzymatic activity assay of ß-1,3-glucanase revealed that there were more protein bands corresponding to ß-1,3-glucanase isoforms in the infected seeds of resistant genotypes than in the infected seeds of susceptible genotypes. Both acidic and basic ß-1,3-glucanase isoforms were detected in the IEF gel. Thin layer chromatography (TLC) analysis of the hydrolytic products from the reaction mixtures of total protein extract and individual bands of native PAGE revealed the presence of the enzymatic hydrolytic oligomer products. Two bands were revealed on the SDS-PAGE with molecular weight of 10-kDa and 13-kDa, respectively, which are of the individual bands corresponding to the bands of ß-1,3-glucanase isoforms from native PAGE. The 13-kDa protein was the majority. The sequences of the 13-kDa protein showed a high degree of homology to conglutin, a storage protein in peanut seeds. Conglutin is reported as a peanut allergen, Ara h2, and has trypsin inhibitor function. Our results suggest this 13-kDa conglutin-like protein has ß-1,3-glucanase activity and may be associated with resistance to A. flavus conolization in peanut seeds.