title: RNAi Phenotypes and the Localization of a Protein::GUS Fusion Imply a Role for Medicago truncatula PIN Genes in Nodulation.
abstract: The symbiosis between legumes and rhizobia results in the development of a new plant organ, the nodule. A role for polar auxin transport in nodule development in Medicago truncatula has been demonstrated using molecular genetic tools. The expression of a DR5::GUS auxin-responsive promoter in uninoculated M. truncatula roots mirrored that reported in Arabidopsis, and expression of the construct in nodulating roots confirmed results reported in white clover. The localization of a root-specific PIN protein (MtPIN2) in normal roots, developing lateral roots and nodules provided the first evidence that a PIN protein is expressed in nodules. Reduced levels of MtPIN2, MtPIN3, and MtPIN4 mRNAs via RNA interference demonstrated that plants with reduced expression of various MtPINs display a reduced number of nodules. The reported results show that in M. truncatula, PIN proteins play an important role in nodule development, and that nodules and lateral roots share some early auxin responses in common, but they rapidly differentiate with respect to auxin and MtPIN2 protein distribution.
authors.affiliation: Department of Genetics & Biochemistry, Clemson University, Clemson, South Carolina 29634 USA.
authors.forename: Xiuyan
authors.initials: X
authors.lastname: Huo
authors.forename: Elise
authors.initials: E
authors.lastname: Schnabel
authors.forename: Kelley
authors.initials: K
authors.lastname: Hughes
authors.forename: Julia
authors.initials: J
authors.lastname: Frugoli