Ratoon Stunting Disease (RSD) of Sugarcane: A Review Emphasizing Detection Strategies and Challenges

Abstract

Sugarcane (Saccharum hybrid) is an important cash crop grown in tropical and subtropical countries. Ratoon stunting disease (RSD), caused by a xylem-inhabiting bacterium Leifsonia xyli subsp. xyli (Lxx), is one of the most economically significant globally. RSD results in severe yield losses due to its highly contagious nature, lacks of visually identifiable symptoms, make it harder to devise an effective management strategy. Efficacy of the current management practices is hindered by implementation difficulties due to the lack of resources, high cost, and difficulties in monitoring. Rapid detection of the causal pathogen in vegetative planting material is crucial for sugarcane growers to manage this disease. Several microscopic, serological, and molecular-based methods have been developed and used for detecting the RSD pathogen. Although these methods have been used across the sugarcane industry worldwide to diagnose Lxx, some lack reliability or specificity, are expensive, and time-consuming to apply, and most of all, are not suitable for on-farm diagnosis. In recent decades, there has been significant progress in the development of integrated isothermal amplification-based microdevices for accurate human and plant pathogen detection. There is a significant opportunity to develop a novel diagnostic method that integrates nano-biosensing with isothermal amplification within a microdevice format for accurate Lxx detection. In this review, we summarize (i) the historical background and current knowledge of sugarcane ratoon stunting disease, including some aspects related to transmission, pathosystem, and management practices; and (ii) the drawbacks of current diagnostic methods and potential for application of advanced diagnostics to improve disease management.