Volatile Fingerprinting (SPME-GC-FID) to Detect and Discriminate Diseases of Potato Tubers

Abstract

Volatiles from Russet Burbank potatoes inoculated with Erwinia carotovora subsp. carotovora, E. carotovora subsp. atroseptica, Pythium ultimum, Phytophthora infestans, or Fusarium sambucinum were monitored by sampling the head space 3, 4, and 5 days after inoculation, using a solid phase microextraction (SPME) fiber to trap and gas chromatography with flame ionization detector (GC-FID) to fingerprint volatiles. Noninoculated (NON) potatoes served as the control. Volatile fingerprints varied among diseases. Within a disease, the fingerprints varied with time since inoculation and among blocks. In general, more volatiles were observed on the fourth and fifth day after inoculation than on the third day. The amount of volatile compounds produced (peak area) within a disease group increased with incubation time; however, the variation among blocks was much higher. The amount of volatiles produced, in general, was associated with disease severity. Disease-specific volatiles were observed. The F. sambucinum chromatogram had two unique peaks at retention time (RT) = 14.1 and 17.3 min. P. infestans produced few peaks and the profile was quite similar to NON. In contrast, E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Pythium ultimum produced many peaks, and the P. ultimum was different from the bacteria, in that the chromatogram peaks at RT = 4.04 and 8.76 min were absent. Instead, it produced a distinct peak at RT = 1.71 min. E. carotovora subsp. carotovora and E. carotovora subsp. atroseptica couldn't be discriminated based on unique peaks; however, they varied in concentration of volatiles produced. E. carotovora subsp. carotovora produced more of RT = 2.0 min and less of RT = 2.3 and 2.44 min than E. carotovora subsp. atroseptica. A back-propagation network (using neural networks) was developed to classify volatile profiles into six disease-groups. Cross-validation classification probabilities were NON = 71, E. carotovora subsp. carotovora = 71, E. carotovora subsp. atroseptica = 71, P. ultimum = 67, Phytophthora infestans = 46, and F. sambucinum = 75%.

Use of headspace solid-phase microextraction and headspace sorptive extraction for the detection of the volatile metabolites produced by toxigenic Fusarium species

“…The monitoring of fungal volatiles as markers for mycotoxin production and for early detection of fungal infection in grains and agricultural commodities has received increasing interest over the last years [11,12] and is subject of the current study. The correlation between infection of potato tubers and emission of fungal volatiles by F. sambucinum was also demonstrated more recently by a Canadian group [13].…”

Botrytis cinerea infection in three cultivars of chrysanthemum in ‘Alchimist’ and its mutants: Volatile induction of pathogen-infected plants

“…Significant plant VOCs induction has been reported in other systems, such as maize inoculated by Fusarium (Piesik et al, 2011a), potato cv. 'Maris' piper tubers inoculated with Phytophthora infestans and Fusarium coeruleum (Lacy Costello et al, 2001), fungal-inoculated potatoes (Kushalappa et al, 2002), and Fusarium circinatum infection induced higher levels of systemic ethylene emission from Monterey pine foliage (Bonello et al, 2001).…”

Fusarium infection in maize: Volatile induction of infected and neighboring uninfected plants has the potential to attract a pest cereal leaf beetle, Oulema melanopus

“…Significant plant VOC induction has been reported in other systems, such as potato cv. 'Maris' piper tubers inoculated with Phytophthora infestans and Fusarium coeruleum (Lacy Costello et al, 2001), fungal-inoculated potatoes (Kushalappa et al, 2002), and F. circinatum infection induced higher levels of systemic ethylene emission from Monterey pine foliage (Bonello et al, 2001).…”