Characterization of plant carbohydrates and changes in leaf carbohydrate chemistry due to chemical and enzymatic degradation measured by microscopic ATR FT-IR spectroscopy

Leaf litter decomposition is largely effected by the enzymatic action of fu ngal colonizers of leaf material. Microscopic attenuated total reflectance (ATR) infrared spectroscopy would be a useful tool to evaluate changes in l eaf litter carbohydrate chemistry over time during the colonization process at the stale of resolution of the fungal hyphae, This paper reports the fi rst studies to use microspectroscopy in the mid-infrared (IR) region to per form analyses within an area of 250 x 250 mu m to gain spectra of single sp ecies of sugars and complex carbohydrates (cellulose, hemicellulose, lignin ) to identify characteristic IR reflectance peaks and to be able to separat e the species In complex media. Changes in leaf surface carbohydrate chemis try were interpreted from spectra obtained from leaf material that underwen t the following: (1) treatment with acetone (to remove surface waxes), (2) treatment with enzymes, and (3) observation after colonization by fungi. An alysis of spectra obtained from random locations or from the same points on the leaf surface over time permitted changes in carbohydrate chemistry to be detected, Comparative analysis of spectra was carried out by using time- series analysis of variance of selected characteristic peak heights and mul tivariate statistics.