Effect of NaCl on the development of the oil palm vascular wilt fungus, Fusarium oxysporum f. sp. elaeidis.

Jacques S B Dossa,Michaël Pernaci,Euloge C Togbé,Euloge K Agbossou,Bonaventure C Ahohuendo

doi:10.33687/phytopath.008.01.2788

Jacques S B Dossa, Michaël Pernaci + Show 3 more

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https://doi.org/10.33687/phytopath.008.01.2788

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Abstract

Oil palm Elaeis guineensis Jacq. (Arecaceae) is one of the cash crops that mainly contributes to the gross domestic production of growing countries. This crop is grown worldwide throughout the humid intertropical belt. Its production in Africa is mainly threatened by the telluric fungus Fusarium oxysporum f. sp. elaeidis, causal agent of the oil palm vascular wilt. It has been reported that some environmental factors, such as soil and air salinity, may determine the survival, development and severity of phytopathogenic agents including Fusarium. The purpose of this study was to evaluate the effect of NaCl on growth, reproduction and pathogenic traits of this fungus by measuring mycelium daily growth, mycelium dry weight, sporulation rate, germination rate and number of infectious spores under four NaCl concentrations (0 g.L-1, 2.5 g.L-1, 5 g.L-1 ,10 g.L-1) of culture medium (MM solid medium and Armstrong liquid medium). The results indicated that NaCl reduced the radial daily growth and mycelium dry weight. In addition, the NaCl reduced significantly the sporulation rate and number of infectious spores while increasing the germination rate. Overall, these results indicated the negative NaCl effect on the development and the fitness of this pathogenic fungus. Thus, NaCl inputs appeared to be a potential solution for managing Fusarium oxysporum f. sp. elaeidis in the field, if a good balance between a decrease of disease incidence and yield loss is reached.

Highlights

Oil palm, Elaeis guineensis Jacq. of the Arecaceae family is grown worldwide throughout the humid intertropical belt
This study aims at evaluating the influence of NaCl on (i) the growth; (ii) the reproduction ability and (iii) the infectiveness of Foe to evaluate its potential use as a method to control Foe in oil palm plantations
This study evaluated the effects of four various concentrations of NaCl 0, 2.5, 5 and 10 g/L on the growth parameters of Foe through radial daily growth of mycelium and mycelium dry weight; the reproductive ability using sporulation rate and their infectiveness by assessing germination rate and infectious spores

Summary

Introduction

Elaeis guineensis Jacq. of the Arecaceae family is grown worldwide throughout the humid intertropical belt. In vitro tests were performed to evaluate the effect of NaCl on mycelial growth, sporulation and spore germination of Verticillium albo-atrum, Phytophthora capsici, Fusarium oxysporum f. Elaeidis used in this study is the isolate IB7, routinely used for screening test in the laboratory, and kept in the fridge at 4°C on compost soil It was isolated in southern Benin (Guinean zone, Atlantic Department, 6°40’0’’ N and 2°15’0’’E) from a stipe of an oil palm affected with fusariosis, which was incubated on the MM culture medium. To assess the mycelium dry weight, one Petri dish of MM solid medium was prepared and inoculated at the center with a small calibrated amount of compost soil containing Foe. The Petri dish was placed in the incubator at 28°C for four days. R version R-3.4.0 was used to perform all the ANOVAs, Tukey’s and correlation tests

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