Purification of a new fungal mannose-specific lectin from Penicillium chrysogenum and its aphicidal properties.

Several Ascomycetes fungi are commonly used in bio-industries and provide available industrial residues for lectin extraction to be valuable. A lectin from Penicillium chrysogenum, named PeCL, was purified from a fungal culture using gel-filtration chromatography column. PeCL was found to be a mannose-specific lectin by haemagglutination activity towards rabbit erythrocyte cells and was visualised on SDS-PAGE gel. Purified PeCL fraction was delivered via artificial diet to Myzus persicae aphid and was demonstrated to be aphicidal at 0.1 % with higher toxic efficiency than a known mannose-binding lectin Concanavalin A (ConA). A fast and efficient way to purify PeCL and a potential use in pest control is described.

Investigation of carbohydrate binding property of a fungal lectin from Xerocomus chrysenteron and potential use on Myzus persicae aphid.

In recent years encoding insecticidal Lectins have been suggested as one of the promising methods against insect pests and have been engineered successfully into a variety of crops including wheat, rice, tobacco and potatoes. Xerocomus chrysenteron Lectin (XCL) has a high hemagglutinating activity and results obtained from sugar specificity assay showed to have specific affinity to Galactose and N-Acetylgalactosamine (GalNAc). In previous studies, XCL was shown to have negative effects on some insect pests, including aphids. In the present study, the effects of different carbohydrates including D-glucose, D-mannose, D-galactose and GalNAc, associated with 0.1% XCL (w/v) in artificial diet was investigated to assess the evolution of the lectin toxicity toward Myzus persicae aphid during 7 days. M. persicae, a polyphagous aphid, showed no significant differences of mortality when fed with the XCL lectin associated with Glucose and Mannose or fed on XCL diet only. At the opposite, the mortality rates related to artificial diet supplemented with Galactose or GalNAc and XCL were significantly reduced. There was then a significant mortality difference between M. persicae fed on an artificial diet incorporated specific carbohydrate binding Lectin with those fed with lectin only. The potential use of this particular fungal Lectin (XCL) with more specific carbohydrate binding will be discussed in relation to the development of bio-insecticide and integrated pest management.

Effect of a fungal lectin from Xerocomus chrysenteron (XCL) on the biological parameters of aphids.

Aphids are important pests of crop plants in Europe. Increasing resistance of aphids to insecticides and their side effects on the environment and non target organism's including human's stimulated research on alterative methods of aphid control, including the use of entomotoxic proteins. Lectins are carbohydrate binding proteins that are widely distributed in nature; they have been isolated from microorganisms, fungi, plants and animals. Several of these proteins were tested for their potential biocide effect on plenty of pests. A fungal lectin, namely Xerocomus Chrysenteron lectin (XCL) was previously purified and was shown to be toxic for several pests including aphids. XCL was clearly the most toxic lectin against M. persicae. In this work, bioassays using artificial diets incorporating a broad range of XCL concentrations (from 10 microg x ml(-1) to 5000 microg x ml(-1)) were developed to assess the negative effects of XCL on the biological parameters (development duration, weight and fecundity) of M. persicae a polyphagous aphid found on more than 400 host plant species and transmitting more than 100 viral diseases. A significant mortality of aphids was observed, corresponding to the LC50 and LC90 of 0, 46 and 6, 02 mg/ml respectively after 24hrs. Significant differences of M. persicae weight, development duration and fecundity (P < 0.05) was observed between the tested XCL concentrations. Conavalia ensifomris lectin (ConA) was included as lectin reference on the bioassay experiments and was shown to be less toxic and induced lower negative changes in M. persicae biological parameters when compared with XCL.