The distribution of the carboxylating enzyme nbulose-l,5-bisphosphate carboxylase/oxygenase (RuBPCO) and an enzyme of the photorespiratory pathway (glycine decarboxylase) was determined within the leaf tissue by immunocytochemical techniques in C3, C4 and C3:C4 intermediate species. The specificity of the method for all the materiál was demonstrated by sodium dodecyl sulphate acrylamide gels and Western blotting of crude protein extracts. In the C3 species (wheat) the enzymes were located in chloroplasts (RuBPCO) and mitochondria (glycine decarboxylase) of mesophyll cells, while in the three "classical" C4 standards, i.e. Zea mays ("NADP-ME" type). Panicům maximum ("PCK" type) and P. turgidum ("NAD-ME" type), these were found exclusively in the respective organelles of the bundle sheath. In the intermediate species, RuBPCO was not compartmented as it was located in chloroplasts of mesophyll and bundle sheath cells. Yet glycine decarboxylase was found exclusively in bundle sheath mitochondria. InAristida funiculata, a C4 species with "non-classical" leaf structure, RuBPCO was found in chloroplasts of both the inner and outer bundle sheaths and glycine decarboxylase was located exclusively in mitochondria of the inner bundle sheath cells. It is suggested that A. funiculata may be a C4 species with C3:C4-like intermediate characteristics based on the observed distribution of glycine decarboxylase, although gas-exchange characteristics of this species are required before any reclassification can be considered.
Within each mango (Mangifera indica L.) tree there is a diversity in flowering ability among its terminál branches. Significant variations in net photosynthetic rate (Pn), transpiration rate, stomatal conductance (gj) and mesophyll efficiency (mesophyll capacity to fix CO2) were observed generally among the productive branches. However, the extent of variation was more pronounced in trees with irregular bearing habits (cv. Langra) as compared to regular bearers (cv. Romani). In generál, correlation coefficients indicated that variations in among n5 branches were mainly due to the mesophyll efficiency and g^, In regular bearing trees, the narrow range of variation in was related to a better mesophyll capacity. This in tum might result in higher carbon build-up of 05 branches which would háve helped them to flower regularly with minimum branch to branch variations.
Influence of moderate chilling stress on vascular bundle sheath cell (BSC) and especially mesophyll cell (MC) chloroplasts of mature maize leaves was studied by electron microscopy and stereology. Plants of two inbred lines of maize, differing in their photosynthetic activity, and their F1 hybrids were cultivated during autumn in heated or unheated glasshouse. Generally, chilling temperatures resulted mainly in the decrease in stereological volume density (VD) of both granal and intergranal thylakoids of MC chloroplasts, while the ratio of granal to all thylakoids (granality) was less affected. The VD of peripheral reticulum and plastoglobuli usually increased after cold treatment of plants. The volume of MC chloroplasts usually increased under chilling stress, the shape of the chloroplasts changed only slightly. The ultra-structure of chloroplasts differed between individual genotypes; chilling-stressed hybrid plants showed positive heterosis particularly in the granal thylakoids' VD of MC chloroplasts. and J. Kutík ... [et al.].