Arabidopsis ALF4 encodes a nuclear-localized protein required for lateral root formation.
Lateral root formation, the primary way plants increase their root mass, displays developmental plasticity in response to environmental changes. The aberrant lateral root formation (alf)4-1 mutation blocks the initiation of lateral roots, thus greatly altering root system architecture. We have positionally cloned the ALF4 gene and have further characterized its phenotype. The encoded ALF4 protein is conserved among plants and has no similarities to proteins from other kingdoms. The gene is present in a single copy in Arabidopsis. Using translational reporters for ALF4 gene expression, we have determined that the ALF4 protein is nuclear localized and that the gene is expressed in most plant tissues; however, ALF4 expression and ALF4's subcellular location are not regulated by auxin. These findings taken together with further genetic and phenotypic characterization of the alf4-1 mutant suggest that ALF4 functions independent from auxin signaling and instead functions in maintaining the pericycle in the mitotically competent state needed for lateral root formation. Our results provide genetic evidence that the pericycle shares properties with meristems and that this tissue plays a central role in creating the developmental plasticity needed for root system development.
DiDonato
Raymond J
RJ
Department of Biology, Boston University, Boston, MA 02125, USA. prodriguez@ibmcp.upv.es
Arbuckle
Erin
E
Buker
Shane
S
Sheets
Jill
J
Tobar
José
J
Totong
Ronald
R
Grisafi
Paula
P
Fink
Gerald R
GR
Celenza
John L
JL
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D002467:Cell Nucleus / Q000235:genetics*; D003001:Cloning, Molecular; D017931:DNA Primers; D008938:Mitosis; D008969:Molecular Sequence Data; D018517:Plant Roots / Q000254:growth & development*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D029681:Arabidopsis Proteins; D017931:DNA Primers