POSITIONAL CLONING OF THE FR LOCUS

Project: Research project

Project Details

Description

DESCRIPTION: This proposal deals with the topic of nuclear-mitochondrial
interactions. The question of how the nuclear genome maintains normal
mitochondrial function in higher eukaryotes is addressed. In particular,
the proposal focuses on the possible mechanisms that regulate
segregation and transmission of mitochondria in a heteroplasmic
population, and those that preclude the accumulation of mitochondrial
mutations. The system under study is an interesting nuclear-
mitochondrial interaction in common bean. The mitochondrial mutation
is a cytoplasmic male sterility (CMS) mutation that results in the
inability of the plant to produce viable pollen. The CMS trait in bean
is associated with an insertion in the mitochondrial genome which
generates a novel open reading frame designated pvs-orf239. The
association of a mitochondrial rearrangement and production of novel
proteins are a common theme in plant CMS systems. However, the bean CMS
system has some unique features. The expression of the pvs protein
during development of the pollen meiocytes leads to the accumulation of
this aberrant protein not in mitochondria as expected but at the
periphery of the cell in the developing callose layer. This presumably
interferes with the cytokinesis events that lead to the production of
normal pollen grains. Fertility is restored in strains containing the
mitochondrial mutation by the action of one of several nuclear restorer
genes. One of these genes, the Fr locus, is the focus of this
proposal. Fr restores fertility to the CMS strain apparently by
effecting the directed elimination of the mitochondrial mutation. To
elucidate the molecular basis of Fr action, the proposal outlines a
series of experiments aimed at the positional cloning of Fr. Physical
mapping of the locus, the construction of a large-insert library for use
in chromosome walking from tightly linked markers, and the isolation of
cDNA clones derived from the putative Fr gene are outlined.
StatusFinished
Effective start/end date6/1/9611/30/98

Funding

  • National Institute of General Medical Sciences
  • National Institute of General Medical Sciences

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