An investigation of wound healing in sugar beet roots using light and fluorescence microscopy

Following impact, wound healing was investigated in roots of sugar beet usi ng fluorescence microscopy in conjunction with a conventional lignin test. Samples of sugar beet roots were harvested at different stages of developme nt and impacted in the laboratory with a falling bolt delivering 1-4 Joules . A response in the form of deposition of brown material, presumed to be me lanin, along the outer and inner walls of cells at the wound surface was ob served within 3 d of impact. This material eventually became granular in ap pearance. Formation of a ligno-suberized boundary layer from cells present at the time of impact first occurred in 16-week-old roots 9 d after impact. Intensity of calcofluor fluorescence supported the findings made using lig ht microscopy. As wound healing progressed with time, the intensity of calc ofluor fluorescence declined, demonstrating interference by wound healing p roducts with calcofluor binding. Aggressive harvest and subsequent storage dramatically reduced calcofluor fluorescence indicating that this dye may h ave potential value in the assessment of tissue damage. (C) 2001 Annals of Botany Company.