© 2005 Heron Publishing—Victoria, Canada
Fourier transform-infrared spectroscopy as a new method for evaluating host resistance in the Dutch elm disease complex
J. A. Martín (1), A. Solla (2), S. Woodward (3) and L. Gil (1, 4)
1. Anatomía, Fisiología y Mejora Genética Forestal, ETSI de Montes, Universidad Politécnica de Madrid, Paseo de las Moreras s/n,
28040 Madrid, Spain / 2. Biología y Producción de los Vegetales, Ingeniería Técnica Forestal, Universidad de Extremadura, Avenida Virgen del Puerto
2, 10600 Plasencia, Spain / 3. School of Biological Sciences, University of Aberdeen, Aberdeen AB24 4FA, Scotland, UK / 4. Corresponding author (luis.gil@upm.es) / Received November 2, 2004; accepted February 18, 2005; published online August 1, 2005
Summary
Resistance of elms (Ulmus spp.) to the pathogenic fungus Ophiostoma novo-ulmi Brasier depends on chemical and anatomical factors that confine the spread of the pathogen in the vascular system of the
host. This study focused on detecting chemical differences in 4-year-old Ulmus minor Mill. seedlings before and after inoculation with a virulent O. novo-ulmi isolate. According to symptom development over 60 days, the trees were divided into resistant (0–33% wilting) and susceptible
(67–100% wilting) groups. Histochemical tests and Fourier transform-infrared (FT-IR) spectroscopy analysis were performed
on transverse sections of 2-year-old twigs, 2 days before and 40 days after inoculation. Although histochemical tests did
not clearly discriminate susceptible from resistant elms, chemical differences between resistant, susceptible and control
trees were detected by FT-IR. The average spectrum for resistant tree samples had higher absorbance peaks than the spectra
from the susceptible and control samples, indicating increased formation of lignin and suberin. The roles of lignin and suberin
in the resistance of the elms against O. novo-ulmi and the usefulness and sensitivity of the FT-IR technique for analyzing metabolic changes caused by pathogens in plants are
discussed.
Keywords:
FT-IR, histochemistry, Ophiostoma novo-ulmi, plant defense, Ulmus minor
.
