Activity and activation state of ribulose-1,5-bisphosphate carboxylase of spruce trees with varying degrees of damage relative to the occurrence of novel forest decline

The aim was to determine whether a reduced carboxylation efficiency in needles of damaged spruce trees (Picea abies), is derived from a direct impairment of the ribulose-1,5-bisphosphate carboxylase (RuBP carboxylase) or there is an indirect inhibition of the RuBP carboxylase. In 1985, 1986 and 1987 measurements of RuBP carboxylase activity were carried out at three locations. Trees of different ages and degrees of damage were examined. RuBP carboxylase was assayed using both a rapid extraction method to determine the initial activity and an in vitro test after total activation to determine the total activity. The activation state was calculated as the ratio of initial activity to total activity.Within three vegetation periods the total activity in needles of damaged and apparently healthy or slightly damaged spruce trees indicated no definite difference in the annual average. On the other hand, in damaged needles a continued decline of the actual activation of RuBP carboxylase was established. The observation of continued depression of the activation state of the enzyme in needles of damaged spruce trees can possibly be due to a reduced photosynthetic electron transport rate.The measurements of the soluble protein content indicate a tendency to increased amounts in the needles of damaged trees. In accordance, a considerable increase of the activity of some enzymes like glutamine synthethase, phosphoenol-pyruvate carboxylase, and catalase could be noticed. However, there is no clear connection between the RuBP carboxylase and the content of soluble proteins.

The influence of brassinosteroid on growth and parameters of photosynthesis of wheat and mustard plants

The growth response of wheat (Triticum aest. L.) and mustard seedlings (Sinapis alba L.) treated with 10(-6) mol · l(-1) brassinosteroid (BR) foliar spray was measured. BR-treatment resulted in a general promotion of plant growth. We found the accumulation of photosynthates to be stimulated in the treated plants, as indicated by enhanced fresh and dry weights of leaves and shoots. BR also promoted the synthesis of soluble proteins and soluble reducing sugars, whereas the chlorophyll content was hardly affected. CO(2)-fixation in vivo as well as the (in vitro) RubPC-ase activity of BR-treated leaves were enhanced. In the developing wheat leaves we detected no difference in the ratio fraction-I-protein (F-I-P)/total soluble protein between BR-treated and control plants whereas in the expanded leaves this ratio was lowered under BR-treatment.