IDENTIFICATION OF VOLATILE CHEMICALS THAT CAN BE USED TO DIAGNOSE RATOON STUNTING DISEASE

RATOON STUNTING DISEASE (RSD), caused by Leifsonia xyli subsp. xyli, is one of the most significant diseases to affect sugarcane. Control relies on strict hygiene, including screening of seed cane, sterilisation of equipment, hot water treatment and selective use of partially resistant germplasm. The current standard RSD diagnostic assay is based on an evaporative binding enzyme linked immunosorbent assay (EB-ELISA), which requires sap to be extracted and dried onto an immunoassay plate. Although high throughput is achievable with this method, it is a slow and complicated process. Some species of pathogenic bacteria can be characterised by the volatile chemicals they produce. In this paper, we show that six volatile chemicals are present at significantly higher levels in RSD-infected sugarcane, compared with uninfected plants. Gas chromatography-mass spectrometry analysis of the headspace of sugar sap from infected and uninfected plants identified specific alcohols, ketones and an aldehyde as signatures of RSD infection. We were able to classify the infection status of plants with better than 95% accuracy using this information. We aim to use these volatile biomarkers of RSD to train electronic nose sensors to sniff out contamination with more convenience than current ELISA methods.