XVI International Botanical Congess

Proteoid roots of phosphorus-deficient white lupin excrete phenomenal amounts of citrate and malate. Labeling studies have shown that a significant portion of the carbon excreted is fixed by phosphoenolpyruvate carboxylase (PEPC) in the roots. Proteoid root development is accompanied by: increased specific activity of malate dehydrogenase, citrate synthase, and PEPC, greater amounts of PEPC enzyme protein and mRNA, and increased acid phosphatase secretion from proteoid root segments. Presently, we are isolating and characterizing genes important in proteoid root development and the lupin P-deficiency response, and evaluating their tissue and cellular expression patterns.