Early Detection of the Fungal Banana Black Sigatoka Pathogen Pseudocercospora fijiensis by an SPR Immunosensor Method

Abstract

Black Sigatoka is a disease that occurs in banana plantations worldwide. This disease is caused by the hemibiotrophic fungus Pseudocercospora fijiensis, whose infection results in a significant reduction in both product quality and yield. Therefore, detection and identification in the early stages of this pathogen in plants could help minimize losses, as well as prevent the spread of the disease to neighboring cultures. To achieve this, a highly sensitive SPR immunosensor was developed to detect P. fijiensis in real samples of leaf extracts in early stages of the disease. A polyclonal antibody (anti-HF1), produced against HF1 (cell wall protein of P. fijiensis) was covalently immobilized on a gold-coated chip via a mixed self-assembled monolayer (SAM) of alkanethiols using the EDC/NHS method. The analytical parameters of the biosensor were established, obtaining a limit of detection of 11.7 µg mL−1, a sensitivity of 0.0021 units of reflectance per ng mL−1 and a linear response range for the antigen from 39.1 to 122 µg mL−1. No matrix effects were observed during the measurements of real leaf banana extracts by the immunosensor. To the best of our knowledge, this is the first research into the development of an SPR biosensor for the detection of P. fijiensis, which demonstrates its potential as an alternative analytical tool for in-field monitoring of black Sigatoka disease.

A Novel Enzyme-Based SPR Strategy for Detection of the Antimicrobial Agent Chlorophene

“…Homogeneous thin films of Cr/Au were deposited on thin glass substrates by electron gun evaporation, following the method described by Luna-Moreno [ 33 ]. Briefly, the chromium layer was evaporated up to a 3 nm thickness.…”

Optical Thickness Monitoring as a Strategic Element for the Development of SPR Sensing Applications

“…The first sensing application reported in [21] was the detection of different alcohol content ranging from 35 to 46%v/v, where 1 mL of isopropyl alcohol was evaporated and delivered over the Au film, then measured by SPR at 43.6 • to later be compared with the signal obtained in air. As a second application, reported in [22], the biofunctionalization of a gold film was evaluated in real-time by SPR, employing the EDC/NHS method for the immobilization of a polyclonal antibody (50 µg mL −1 ) onto the gold surface. The obtained signals from the antibody-antigen effect were directly proportional to the concentration of antigen (39.1-122 µg mL −1 ) in the samples.…”

“…On the other hand, ideal films like the one obtained in substrate X1 are strong candidates to be employed in biosensing applications. Figure 3e shows the use of this film in the biofunctionalization of the thin gold layer, performed in a recent work [22].…”

Multivariate analyses to determine fungicide efficacy on Ecuadorian bananas for consumption

“…The most effective disease management is through the application of fungicides according to their different modes of action. The fungicides work by interfering in vital processes of the pathogen (Bolaños, 2006;Luna-Moreno et al, 2019;Martínez-Bolaños et al, 2012;Martínez et al, 2011;Romero & Sutton, 1997).…”

“…Half maximal effective concentration EC 50 is a standard measurement that has been widely used in sensitivity analyses for chemical products in pathogen control, especially in black sigatoka disease, which belong to the most important annual bioassays for decision makers to keep tested fungicides in market. To examine the effectiveness of a fungicide and changes in sensitivity, P. fijiensis response is commonly analyzed under the EC 50 (Bolaños, 2006;Luna-Moreno et al, 2019;Martínez-Bolaños et al, 2012;Martínez et al, 2011;Romero & Sutton, 1997). Traditional analyses on fungicide efficacy take into account doses and inhibition percentages for a regression model from which a dose response curve is determined.…”