Mutations in the microRNA complementarity site of the INCURVATA4 gene perturb meristem function and adaxialize lateral organs in arabidopsis.
Here, we describe how the semidominant, gain-of-function icu4-1 and icu4-2 alleles of the INCURVATA4 (ICU4) gene alter leaf phyllotaxis and cell organization in the root apical meristem, reduce root length, and cause xylem overgrowth in the stem. The ICU4 gene was positionally cloned and found to encode the ATHB15 transcription factor, a class III homeodomain/leucine zipper family member, recently named CORONA. The icu4-1 and icu4-2 alleles bear the same point mutation that affects the microRNA complementarity site of ICU4 and is identical to those of several semidominant alleles of the class III homeodomain/leucine zipper family members PHABULOSA and PHAVOLUTA. The icu4-1 and icu4-2 mutations significantly increase leaf transcript levels of the ICU4 gene. The null hst-1 allele of the HASTY gene, which encodes a nucleocytoplasmic transporter, synergistically interacts with icu4-1, the double mutant displaying partial adaxialization of rosette leaves and carpels. Our results suggest that the ICU4 gene has an adaxializing function and that it is down-regulated by microRNAs that require the HASTY protein for their biogenesis.
Ochando
Isabel
I
División de Genética, Universidad Miguel Hernández, Campus de San Juan, 03550 Alicante, Spain.
Jover-Gil
Sara
S
Ripoll
Juan José
JJ
Candela
Héctor
H
Vera
Antonio
A
Ponce
María Rosa
MR
Martínez-Laborda
Antonio
A
Micol
José Luis
JL
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D017343:Genes, Plant; D018519:Meristem / Q000502:physiology*; D035683:MicroRNAs / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D029681:Arabidopsis Proteins; D035683:MicroRNAs