Photosynthetica 1998, 35(3):361-367 | DOI: 10.1023/A:1006908217443
Changes in Ultrastructure of Phaseolus Vulgaris L. Cotyledons Associated with their Modulated Life Span
- 1 Department of Plant Physiology, Faculty of Sciences, Charles University, Praha 2, Czech Republic
- 2 Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Praha 6, Czech Republic
French bean (Phaseolus vulgaris L.) cotyledons lost most of their reserve substances during several early days of germination and turned green. In cotyledon mesophyll cells of one-week-old seedlings, plastids were represented predominantly by amyloplasts (starch grains) and chloroamyloplasts, and the cells appeared to be metabolically highly active. Cell heterogeneity associated with distance of the cells from cotyledon vascular bundles was evident. Only mesophyll cells near to the bundles were rich in plastids. In two-weeks-old intact bean plants, the cotyledons were yellow and shrunken, and their cells were nearly "empty". The plastids in them were represented by senescent plastids (gerontoplasts) only. In the gerontoplasts as well as freely in cytosol, fluorescent lipoid inclusions were accumulated. This cotyledon development was more or less independent of irradiance. In "decapitated" bean plants, senescence of mesophyll cells and plastids was slowed down considerably, and the life span of the cotyledons was prolonged.
Additional key words: cell ultrastructure; chloroamyloplasts; chloroplasts; electron microscopy; fluorescence microscopy; French bean; gerontoplasts; senescence
Prepublished online: September 1, 1998; Published: January 1, 1998 Show citation
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