Roberto Gaxiola studies the physiological mechanisms by which plants regulate root activity and nutrient uptake. Facing the problem of insufficient agricultural production in the midst of a growing worldwide population, Gaxiola and his research team hope to find ways to augment plant root biomass — a key strategy for developing cultivated crops that use water and nutrients more effectively.
Using genetic and physiological experiments, the researchers have characterized a protein within plant membranes that controls how sugar moves from leaves to roots. By artificially enhancing this protein, root activity and plant nutrient absorption are greatly increased, resulting in more robust root systems with improved water and nutrient uptake efficiency.
Gaxiola's work may be used to engineer crops that could help secure future food supplies.
·Julio Paez-Valencia, Jonathan Lares-Sanchez, Ellen Marsh, Liane T. Dorneles, Mirella P. Santos, Alexander Winter, Sean Murphy, Jennifer Cox, Marcin Trzaska, Jason Metler, Alex Kozic, Charles A. Sanchez, Arnoldo Francana, Daniel Schachtman, and Roberto A. Gaxiola. (2013). Enhanced H+-PPase activity improves nitrogen use efficiency in Romaine Lettuce. Plant Physiology 161, 1 - 13.
·Roberto A. Gaxiola, Charles A. Sanchez, Julio Paez-Valencia, and James J. Elser (2012). H+-PPases and Pi limitation. Genetic Manipulation of a “Vacuolar” H+-PPase: From Salt Tolerance to Yield Enhancement Under Phosphorus-Deficient Soils. Plant Physiology. 159: 1-9.
·S. Undurraga, M. P-Santos, J. Paez-Valencia, H. Yang, P.K. Hepler, A.R. Facanha, K.D. Hirschi, R. A. Gaxiola. (2012) Arabidopsis sodium dependent and independent phenotypes triggered by H+-PPase up-regulation are SOS1 dependent. Plant Science. 183: 96-105.
·Paez-Valencia J, Patron-Soberano A, Rodriguez-Leviz A, Sanchez-Lares J, Sanchez-Gomez C, Valencia-Mayoral P, Diaz-Rosas G, Gaxiola R. A. (2011) Plasma membrane localization of the type I H+-PPase AVP1 in sieve element-companion cell complexes from Arabidopsis thaliana. Plant Science 181: 23 – 30.
·Gaxiola R. A., Edwards M, Elser JJ. (2011) A transgenic approach to enhance phosphorus use efficiency in crops as part of a comprehensive strategy for sustainable agriculture. Chemosphere 84: 840 – 845.
Using the model plant Arabidopsis thaliana the Gaxiola’s group has identified a proton pump that utilizes pyrophosphate (H+-PPase). Up-regulation of the H+-PPase enhances plant biomass (top). The group’s working model postulates a reverse function (synthesis of pyrophosphate PPi) for the H+-PPase when present at the plasma membrane of phloem cells. PPi is needed to regulate the transport of sucrose from source to sink tissues.