Photoacoustic spectroscopy : a technique to study plant-pathogen interaction

Photoacoustic spectroscopy (PAS) has been applied to study the plant-pathogen interactions and the pathological diagnosis of diseases in various plant species. The Photoacoustic (PA) spectra of fungal infected leaves and healthy leaves were recorded. The samples of the mustard (B. juncea var. Kranti) leaves infected with Alternaria blight, exhibited a higher PA signal strength than that of the untreated (healthy) leaves of same cultivars as well as that of the cabbage and radish. It has been observed that the PA signal strength obtained from the diseased leaves were consistently higher than that of the healthy leaves for all samples. One of the possible reasons behind this fact is the contribution of larger beat emission through the disease leaves than the healthy leaves, giving rise to higher signal strength. Our investigations also demonstrate the interaction of light radiation with the plant leaves and their pigments. The PA signal recoded from the conidia of different isolates of Alternaria sp. (A. brassicae, A. brassicicola and A. raphani) also show differences in their characteristic graphic patterns.