# Identification of Biomarkers Associated with Phyllosticta citricarpa Tolerance

## TL;DR

This study identifies biomarkers in citrus cultivars that may help explain differences in resistance to citrus black spot disease.

## Contribution

The study identifies specific biomarkers with antifungal properties that could aid in managing citrus black spot.

## Key findings

- Metabolic profiling revealed biomarkers linked to citrus cultivar susceptibility to CBS.
- Propanoic acid and linalool showed complete inhibition of P. citricarpa growth in vitro.
- Multivariate analysis helped identify compounds contributing to disease resistance differences.

## Abstract

Citrus black spot (CBS) is a fungal disease caused by Phyllosticta citricarpa Kiely, (McAlpine Van der Aa), with most cultivars being susceptible to infection. Currently, disease control is based on the application of protective fungicides, which is restricted due to resistance, health and environmental concerns. Although using natural products for disease management is gaining momentum, more advances are required. This study obtained the metabolic profiles of the essential oil and cuticular waxes of two citrus cultivars with a varying susceptibility to CBS infection using gas chromatography–mass spectrometry. A multivariate data analysis identified possible biomarker compounds that contributed to the difference in susceptibility between the two cultivars. Several identified biomarkers were tested in vitro for their antifungal properties against P. citricarpa. Two biomarkers, propanoic acid and linalool, were able to completely inhibit pathogen growth at 750 mg/L and 2000 mg/L, respectively.