Morphological and cellular changes in rice roots (Oryza sativa L.) caused by Al stress.

Aluminium toxicity significantly limits crop productivity in acid soils and its effects are primarily root-related. The aim of this paper was to study the effects of aluminium on the morphology and cell structure of rice roots. Different AlCl3 levels were employed to impose stress conditions. Apical root segments were processed using a Progressive Low Temperature Method (PLT) and Lowycril resin, so that the samples could be cut. The stained sections were viewed and photographed using a Zeiss Optic microscope with an attached digital camera. Root elongation was reduced in seedlings exposed to Al, accompanied by deformed roots. Some structural changes were detected in epidermal and cortical cells. Reduced length accompanied by radial expansion contributed to cell elongation inhibition in different cellular types. Thickened cell walls and a vacuole size increase were also observed. These results provide evidence of the structural changes provoked in rice root cells by toxic levels of aluminium, as well as the morphological changes observed in Al-stressed rice roots in our laboratory.