ABSTRACT

When there is no major difficulty in latex flow it can be considered that production of rubber reflects the intensity of the metabolism within these specialized cells that constitute the laticiferous system. The central role of the "phosphoenolpyruvic acid crossroads" in the regulation of pH and plant metabolism was pointed out by Davies. Insofar as it has been demonstrated with certainty that the functioning of phosphoenolpyruvate carboxylase in latex cytosol does produce organic acids, accumulation of the latter can induce significant acidification of the cytosol, resulting in self-regulation which tends to inhibit enzyme activity itself. The influence of metabolites and ion compartmentation on the intensity of the cytosol metabolism were revealed in detail by studies of the compartmentation of solutes in latex set against production of rubber. Both native lutoids and tonoplast vesicles were shown to accumulate exogenous citrate against a steep concentration gradient. Divalent cations also accumulate in lutoids in vivo.