title: Phenotypic characterization of the CRISPA (ARP gene) mutant of pea (Pisum sativum; Fabaceae): a reevaluation.
abstract: OBJECTIVE
  Leaf form and development are controlled genetically. The ARP genes encode MYB transcription factors that interact with Class 1 KNOX genes in a regulatory module that controls meristem-leaf determinations and is highly conserved in plants. ARP loss of function alleles and subsequent KNOX1 overexpression cause many unusual leaf phenotypes including loss or partial loss of the ability to produce a lamina and production of "knots" on leaf blades. CRISPA (CRI) is the ARP gene in pea, and a number of its mutant alleles are known.
  
  
  METHODS
  We made morphological and anatomical evaluations of cri-1 mutant plants while controlling for genetic background and for heteroblastic effects, and we used aldehyde fixation and resin preparations for anatomical analysis. Further, we compared gene expression in WT and cri-1 shoot tips and HOP1/PsKN1 and CRI expression in other leaf mutants.
  
  
  RESULTS
  The cri-1 plants had more extensive abnormalities in the proximal than in the distal regions of the leaf, including ectopic stipules, narrow leaflets, and shortened petioles with excessive adaxial expansion. "Knots" were morphologically and anatomically variable but consisted of vascularized out-pocketing of the adaxial leaflet surface. HOP1/PsKN1 and UNI mRNA levels were higher in cri-1 shoot tips, and some auxin-regulated genes were lower. Low LE expression suggests that the GA level is high in cri-1 shoot tips.
  
  
  CONCLUSIONS
  The CRISPA gene of pea suppresses KNOX1 genes and UNI and functions to (1) maintain proximal-distal regions in their appropriate positions, (2) restrict excessive adaxial cell proliferation, and (3) promote laminar expansion.
authors.affiliation: Botany and Plant Sciences, University of California, Riverside, California, 92521 USA.
authors.forename: Darleen A
authors.initials: DA
authors.lastname: DeMason
authors.forename: Venkateswari
authors.initials: V
authors.lastname: Chetty
mesh_terms: D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D018519:Meristem / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D009154:Mutation; D018532:Pisum sativum / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018520:Plant Shoots / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D018398:Homeodomain Proteins; D007210:Indoleacetic Acids; C405985:Knox1 protein, plant; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014157:Transcription Factors
keywords: ARP genes; CRISPA; Fabaceae; Pisum sativum; UNIFOLIATA; adaxial meristem; compound leaves; knots; leaf development