At the whole plant level, the effect of stress is usually perceived as a de
crease in photosynthesis and growth. That is why this review is focused mai
nly on the effect of drought on photosynthesis, its injury, and mechanisms
of adaptation. The analysed literature shows that plants have evolved a num
ber of adaptive mechanisms that allow the photochemical and biochemical sys
tems to cope with negative changes in environment, including increased wate
r deficit. In addition, the acquisition of tolerance to drought includes bo
th phenotypic and genotypic changes. The approaches were made to identify t
hose metabolic steps that are most sensitive to drought. Some studies also
examined the mechanisms controlling gene expression and putative regulatory
pathways.