Interallelic complementation at the Arabidopsis CRE1 locus uncovers independent pathways for the proliferation of vascular initials and canonical cytokinin signalling.
The differentiation of vascular tissue plays a central role in root architecture and its functionality. Regardless of its importance, the molecular mechanisms involved in the inception of vascular morphogenesis and their interaction with hormones are only now beginning to be understood. The characterisation of the WOODEN LEG (wol/cre1 mutant), impaired in procambial cell proliferation and the identification of WOL/CRE1 as a cytokinin receptor, provided the first genetic evidence pointing to a role of cytokinins in the formation of vascular initials. However, the striking wol phenotype in vascular differentiation is unique among all the available cre1 alleles collection. In this work, we identified a mutant with identical deficiencies in vascular differentiation as wol. Complementation analysis revealed that this mutant rescued the wol short-root phenotype. However, genetic characterisation of the mutant showed that the mutation was located at the CRE1 locus, indicating that both alleles displayed interallelic complementation. Trans-heterozygotes characterisation showed that these plants fully restored the deficiency in vascular differentiation but not the canonical cytokinin signalling. Furthermore, we show that, as measured in root growth inhibition, calli regeneration assays and northern analysis, the original wol allele is in fact more sensitive to cytokinins than the trans-heterozygous plants, or some cre1 alleles showing wild-type vascular morphogenesis. Thus, there is no strict correlation between the phenotype in vascular differentiation displayed by the cre1/wol alleles and canonical cytokinin signalling. These results indicate that at least partially independent regulatory circuits may operate in procambial cell proliferation and in cytokinin responsiveness exerted through the CRE1 receptor.
de León
Berenice García-Ponce
BG
Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Campus de la Universidad Autónoma de Madrid Cantoblanco, 28049 Madrid, Spain.
Zorrilla
Jose Manuel Franco
JM
Rubio
Vicente
V
Dahiya
Preeti
P
Paz-Ares
Javier
J
Leyva
Antonio
A
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division; D003583:Cytokinins / Q000378:metabolism*; D017343:Genes, Plant; D005816:Genetic Complementation Test; D006579:Heterozygote; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D018517:Plant Roots / Q000254:growth & development; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D029681:Arabidopsis Proteins; D003583:Cytokinins; D011956:Receptors, Cell Surface; D011494:Protein Kinases; C421783:WOL protein, Arabidopsis