Postdoc North Carolina State University Raleigh, North Carolina
Body of Abstract: As sessile organisms, plants grow and develop in tune with their environment. They rely on an extensive set of regulatory molecules, that includes phytohormones, that together coordinate plant adaption to changes in the environment. Auxin is a phytohormone involved in nearly every aspect of plant’s life, from embryo development to fruit ripening. Proper spatiotemporal patterns of auxin biosynthesis, transport, catabolism, and response are essential for plant’s phenotypic plasticity and fertility. Plants utilize amino acid tryptophan to make indole-3-pyruvic (IPyA) acid, which is then converted to the primary auxin, indole-3-acetic acid (IAA). Several IPyA-independent routes have been proposed to exist in plants, but their characterization is limited and their contribution to auxin pools is controversial. Over the years, a number of published reports suggested the possible convergence of metabolic pathways for IAA biosynthesis and the production of defense-related compounds, indole glucosinolates and camalexins, via the CYP71A, NITRILASE and AMIDASE gene families. However, the firm proof for that pathway crossover from a genetic point of view is lacking. Hence, in the past 10 years, our group has generated a collection of Arabidopsis mutants harboring different combinations of gene knockouts for these alternative IAA biosynthesis pathways. We have generated cyp71a12/13/18 triple, nit1/2/3/4 quadruple mutants and amidase/ translocon of the outer envelope membrane of chloroplasts/fatty acid amide hydrolase septuple family knockout. We have also introgressed these mutations into an indole glucosinolate pathway mutant, sur2, which overproduces IAOx, as well as combined some of these mutants with a mild IPyA-deficient mutant, wei8. In this work, phenotypic and metabolic analysis of these Arabidopsis mutants will be presented, thus providing evidence that these gene families are not prominently involved in IAA biosynthesis under standard growth conditions.