Poster: Plant-symbiont interactions

Abs # 584: LATd: a gene required both for nodulation and root development

Presenter:	Liang, Yan , yan.liang@uvm.edu
Authors	Liang, Yan  (A)   Harris, Jeanne  (A)
Affiliations:	(A): Universitiy Of Vermont, Botany Department

The developmental program of nodulation is regulated by plant genes. Here we report a mutation,latd (lateral root organ defective) of the model legume Medicago truncatula, which disrupts both nodule and root development. Latd mutant nodules are smaller than wild type and cannot fix nitrogen. Latd mutants also have short primary root, short lateral root, short and sparse root hairs and a lumpy root tip. Interestingly, we have found that the latd mutant phenotype can be partially rescued by abscisic acid (ABA) but not gibberellin, cytokinin, ethylene, or auxin. These data suggest that ABA may have a function in the regulation of root and nodule development. Thus, latd mutants may have a defect in ABA synthesis or signaling. Alternatively, ABA may bypass a process defective in latd mutants. To distinguish between these possibilities, we measured ABA endogenous concentration in latd mutants. Preliminary data suggest that latd mutant plants appear to synthesize normal levels of ABA, which suggests that latd has a defect in response to ABA. In order to learn more about the molecular function of LATD gene product, we are identifying LATD by positional cloning and have mapped it to the top of chromosome 1. In this way we hope to learn more about the role of the LATD gene in nodulation and root development.