Submitted to: Plant Cell Signaling Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 2005
Publication Date: February 1, 2005
Citation: Porch, T.G., Tseung, C., Schmelz, E.A., Settles, M. 2005. The maize viviparous13 locus encodes the cnx1 gene required for molybdenum cofactor biosynthesis [abstract]. Plant Cell Signaling Conference. Technical Abstract: Abscisic acid (ABA), auxin, and nitrate are important signaling molecules that affect plant-environment growth responses. The synthesis and metabolism of these compounds depends upon the molybdenum cofactor (Moco). Maize viviparous13 (vp13) mutants have characteristic seedling lethal phenotypes consistent with disruptions in ABA, auxin, and nitrate signaling. We devised a novel PCR-based method to clone a transposon tagged allele of vp13. Vp13 encodes the ortholog of plant Cnx1 or mammalian gephyrin. Gephyrin catalyzes the final common step of Moco synthesis and is a scaffolding protein. ABA and auxin levels are reduced in vp13 mutants, and vp13 seedlings lack Moco-dependent enzyme activities. A weak allele of Arabidopsis cnx1 does not disrupt ABA signaling and has an analogous phenotype to sir1, a likely Moco biosynthetic mutation that disrupts auxin signaling. Considering these observations, we propose that the Moco biosynthetic pathway regulates the metabolism of auxin, ABA, and nitrate to influence plant-environmental responses.