Construction of Raman spectroscopic fingerprints for the detection of Fusarium wilt of banana in Taiwan

Abstract

Banana (Musa sp.) is cultivated worldwide and is one of the most popular fruits. The soilborne fungal disease Fusarium wilt of banana (FWB), commonly known as Panama disease, is caused by Fusarium oxysporum f. sp. cubense (Foc) and is a highly lethal vascular fungal disease in banana plants. Raman spectroscopy, an emerging laser-based technology based on Raman scattering, has been used for the qualitative characterization of biological tissues such as foodborne pathogens, cancer cells, and melamine. In this study, we describe a Raman spectroscopic technique that could potentially be used as a method for diagnosing FWB. To that end, the Raman fingerprints of Foc (including mycelia and conidia) and Foc-infected banana pseudostems with varying levels of symptoms were determined. Our results showed that eight, eleven, and eleven characteristic surface-enhanced Raman spectroscopy peaks were observed in the mycelia, microconidia, and macroconidia of Foc, respectively. In addition, we constructed the Raman spectroscopic fingerprints of banana pseudostem samples with varying levels of symptoms in order to be able to differentiate Foc-infected bananas from healthy bananas. The rate at which FWB was detected in asymptomatic Foc-infected samples by using the spectral method was 76.2%, which was comparable to the rates previously reported for other FWB detection methods based on real-time PCR assays, suggesting that the spectral method described herein could potentially serve as an alternative tool for detecting FWB in fields. As such, we hope that the developed spectral method will open up new possibilities for the on-site diagnosis of FWB.

Raman Spectroscopy Enables Confirmatory Diagnostics of Fusarium Wilt in Asymptomatic Banana

“…The early diagnosis using RS may be able to provide better options to manage Fusarium wilt in banana fields. Previous research has evaluated the applicability of RS for detecting banana Fusarium wilt ( Lin et al, 2020 ). Although proving the ability of RS to detect signatures unique to Fusarium wilt at an early stage in disease progress, the method used in the earlier study still relied on pseudostem tissue for early detection.…”

“…Delayed test results may lead to greater spread of plant diseases ( Schaad et al, 2003 ). Further complicating matters, banana leaves do not exhibit Fusarium wilt symptoms until the plant has become irrevocably damaged ( Lin et al, 2020 ). The current best diagnostics of FOC conducted with asymptomatic plants at the early infection stage requires taking samples from pseudostems; however, this sampling process is destructive, after which the plants may be destroyed.…”

Rapid Detection of Fusarium oxysporum Using Insulated Isothermal PCR and a Rapid, Simple DNA Preparation Protocol

“…Fusarium oxysporum produces durable thick-walled chlamydospores that are highly tolerant to fungicides, which makes it difficult to eliminate the pathogen [ 1 , 6 , 7 , 8 ]. As resting spores, chlamydospores enable Fo to survive in field soil for many years without the presence of hosts [ 1 , 2 , 9 , 10 ].…”

“…To minimize the impact of FW outbreaks, a reliable method for the earlier detection of Fo and diagnosis of FW is required [ 7 , 12 ]. Methods for the efficient diagnosis of crop diseases, especially fungal diseases, in the field help improve disease management.…”

“…Molecular detection techniques, such as conventional polymerase chain reaction (cPCR) [ 13 ], loop-mediated isothermal amplification (LAMP) [ 14 ], SYBR Green quantitative PCR (qPCR) [ 15 ], hydrolysis probe-based qPCR [ 16 ], and real-time LAMP (RealAmp) [ 17 ] assays, have been specially developed for Fo diagnosis. Currently, these methods offer high sensitivity and specificity of detection, which makes them more reliable and faster than conventional methods [ 6 , 7 ]. More importantly, these methods can potentially serve as productive tools to monitor the Fo population in plant tissue [ 13 , 14 , 15 , 16 ] or soil [ 17 , 18 ].…”