Using 1H magnetic resonance imaging and complementary analytical techniques to characterize developmental changes in the Zantedeschia Spreng. tuber

Abstract

Nuclear magnetic resonance imaging (MRI) and complementary analytical techniques were used o examine tissue structure and developmental changes occurring during active growth in the root tuber of Zantedeschia Spreng. cv. Chianti, a commercially significant cut flower. Plants were observed during the period of leaf senescence and tuberization at the end of the first growth cycle of micropropagated plantlets and, following cool storage to break endodormancy, during development occurring after he replanting of ecodormant tubers. MRI distinguished two distinct regions within the tuber, and he differences in the binding state of water in the two regions were reflected in differences in tissue morphology and function. An abundance of free water was observed in tissue comprised of large parenchyma cells, at the base of the tuber. This tissue appeared to be involved in maintaining the viability of the plant during the period of dormancy, a function indicated primarily by increased metabolic activity n this tissue during dormancy, and reduced metabolic activity during periods of active growth. In contrast, water was more tightly bound in tissue comprised of small parenchyma cells. This tissue appeared to operate as a region for dynamic carbohydrate storage. The initial increase in the free water content of this tissue during the growth phase was linked to the mobilization of starch during canopy development. The subsequent decrease in free water in the remainder of the growth period was inked to the reaccumulation of starch while the tuber functioned as a sink for photosynthate prior to canopy senescence.