Department of plant physiology
State Research Center for Optics and Material Sciences
United States of America
2001: Dr.rer.nat (PhD) University of Kaiserslautern, Plant Physiology, Prof. Dr. E. Neuhaus 2001-2004: Head of laboratory, Novoplant GmbH, Gatersleben since 2004: Research Associate at the University of Kaiserslautern, Plant Physiologie
Vacuoles in higher plants fulfill major functions in storage of assimilates and nutrients, storage of toxic organic and anorganic compounds and regulation of turgor and stomata functions. For all of these functions an enormous number of solutes have to pass the vacuolar membrane (tonoplast) and transport of these compounds is mediated by channels and primary and secondary active transporters. Several of these have been identified in the recent past on the molecular level but a large number is still unknown.Malate is one of the major carboxylates accumulating in the vacuole. Beside a specific channel protein, the vacuole contains a malate transporter recently identified by our group (Emmerlich et al. 2003). This transporter (AttDc, A. thaliana tonoplast Dicarboxylate Transporter) is encoded by a single copy gene in Arabidopsis and exhibits highest structural similarity to the Na+/dicarboxylate transporter from mammalian kidneys, located in the proximal tubulus. Homozygote knock out plants lacking AttDC activity reveal strongly reduced leaf malate contents and reduced vacuolar malate and fumerate levels. Interestingly, reduced levels of malate and fumarate are compensated by increased citrate contents. We now raised evidence that plants lacking the vacuolar malate carrier exhibit impaired ability to maintain cytosolic pH homeostasis. Thus, these knock out plants will allow to deepen our insight into plant carboxylate metabolism.