The influence of phosphate deficiency on photosynthesis, respiration and adenine nucleotide pool in bean leaves

Abstract

The decrease in inorganic phosphate (P(i)) content of 10-d-old Phaseolus vulgaris L. plants did not affect rates of photosynthesis (P(N)) and respiration (R(D)), leaf growth, and adenylate concentration. Two weeks of phosphate starvation influenced the ATP content and leaf growth more than P(N) and R(D). The ATP concentration in the leaves of 15- and 18-d-old phosphate deficient (-P) plants after a light or dark period was at least half of that in phosphate sufficient (+P, control) plants. Similar differences were found in fresh and dry matter of leaves. However, P(N) declined to 50 % of control in 18-d-old plants only. Though the R(D) of-P plants (determined as both CO2 evolution and O2 uptake) did not change, an increased resistance of respiration to KCN and higher inhibition by SHAM (salicylhydroxamic acid) suggested a higher engagement of alternative pathway in respiration and a lower ATP production. The lower demand for ATP connected with inhibition of leaf growth may influence the ATP producing processes and ATP concentration. Thus, the ATP concentration in the leaves depends stronger on P(i) content than on P(N) and R(D).