Detection of bacterial infection of agave plants by laser-induced fluorescence

Abstract

Greenhouse-grown plants of Agave tequilana Weber var. azul were inoculated with Erwinia carotovora, the causal agent of stem soft rot. We investigated the laser-induced fluorescence (LIF) of agave plants to determine whether LIF can be used as a noninvasive sensing tool for pathological studies. The LIF technique was also investigated as a means of detecting the effect of the polyamine biosynthesis inhibitor beta-hydroxyethylhydrazine as a bactericide against the pathogenic bacterium Erwinia carotovora. A He-Ne laser at 632.8 nm was used as the excitation source, and in vivo fluorescence emission spectra were recorded in the 660-790-range. Fluorescence maxima were at 690 and 740 nm. The infected plants that were untreated with the bactericide showed a definite increase in fluorescence intensity at both maxima within the first three days after infection. Beginning on the fifth day, a steady decrease in fluorescence intensity was observed, with a greater effect at 740 than at 690 nm. After 30 days there was no fluorescence. The infected plants that had been treated with the bactericide showed no significant change in fluorescence compared with that of the uninfected plants. The ratio of fluorescence intensities was determined to be F 690 nm/F 740 nm for all treatments. These studies indicate that LIF measurements of agave plants may be used for the early detection of certain types of disease and for determining the effect of a bactericide on bacteria. The results also showed that fluorescence intensity ratios can be used as a reliable indicator of the progress of disease.

On-site variety discrimination of tomato plant using visible-near infrared reflectance spectroscopy

“…The USB2000 spectrometer was equipped with a grating (600 lines blazed at 500 nm), a detector (350~1100 nm) with a resolution of 1.5 nm, and an optical fiber cable. The optical fiber was placed 5 mm away from the leaf and directed to the center of the illuminated area at 45° to the light fiber to collect the dispersed light from the leaf as described elsewhere (Cervantes-Martínez et al, 2002). The spectrum of each leaf sample was the average of 5 successive scans.…”

Observation of Climacteric-Like Behavior of Citrus Leaves Using Fluorescence Spectroscopy

“…Besides, it is easy and fast to use for many purposes in both the laboratory and field [4,5]. Studies using chlorophyll fluorescence emission have been applied successfully to detect mineral deficiencies, water and temperature stress, and pathogens in plants [1,[6][7][8][9].…”

Biological Material and Information

“…The insufficiency of minerals always causes the change of the leaf color [5]. The presence of bacterias in plants induces dramatic changes in the process of photosynthesis, and the direct result of it is the change of the leaf color [6]. The changes in genetic structure of a plant result in the change of the emission spectrum of the plant leaves [7].…”