MORPHOMETRIC ANALYSIS OF AGING MUSHROOMS (AGARICUS-BISPORUS) DURING POSTHARVEST DEVELOPMENT

During postharvest development of the basidiocarp of Agaricus bisporus cv.U1, growth takes place in the pileus, stipe and gills. The average cell area in periclinal sections of pileus tissue increases about 5-6 fold. Although the morphology changes, the pileus of the mushroom as a whole does not enlarge, implying that only a minority, estimated to be less than 20% of the cells, are destined to grow by vacuolar expans ion at the cost of other cells. This is in contrast with growth of the gill tissue, as measured in the supporting tissue (the trama), where cells are enlarging in a radial direction by increasing both vacuole v olume and cytoplasm content. However, the absence of an increase in av erage cell size in the longitudinal direction does not match the growt h and growth direction of the gill tissue as a whole. This can only be explained by assuming that each cell in the gill tissue has to divide in the longitudinal direction. Since the stipe architecture shows lar ge variation, observed changes in cell size at one specific point cann ot be used to explain macroscopic changes of the stipe as a whole. A n ew method for correcting shrinkage due to fixation and dehydration pro cedures has also been developed. This method might be useful for a ran ge of organisms in which measurements of absolute or relative cell siz es and intercellular space are required. (C) 1998 Elsevier Science B.V . All rights reserved.