Characterisation of a new allele of pale cress and its role in greening in Arabidopsis thaliana

Mol Gen Genet. 1996 Jul 19;251(5):532-41. doi: 10.1007/BF02173642.


A recessive mutant with white leaves was identified in a screen of a population of T-DNA-tagged Arabidopsis thaliana plants. The mutation is lethal, but plants develop almost to maturity under sterile conditions. The white areas in leaves are devoid of developed chloroplasts, but the plants frequently develop green sectors which contain green chloroplasts. Molecular characterisation of the affected gene revealed that the mutant is allelic to pale cress (pac), a recently described mutation, and was therefore named pac-2. Sequencing of cDNAs and the genomic region revealed several noteworthy features of this genetic locus. In pac-2 the T-DNA had inserted in the region of the promoter and abolished transcription of the PAC gene completely. Cytokinin induced greening in mature, white homozygous pac-2 plants, and therefore is likely to be responsible for the greening observed in callus and shoots induced on roots from such plants. However, the PAC transcript was found to be absent in both white leaves and green callus. Thus, since cytokinin induced greening in the absence of PAC RNA this plant hormone appears to be able to bypass PAC function.

MeSH terms

  • Alleles*
  • Amino Acid Sequence
  • Arabidopsis / drug effects
  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis Proteins*
  • Base Sequence
  • Chloroplasts / genetics*
  • Cloning, Molecular
  • DNA Transposable Elements / genetics
  • DNA, Bacterial / genetics
  • DNA, Complementary / genetics
  • DNA, Plant / genetics
  • Genes, Plant / genetics
  • Genetic Complementation Test
  • Molecular Sequence Data
  • Mutation
  • Plant Growth Regulators / pharmacology
  • Plant Proteins / genetics*
  • Plant Proteins / physiology
  • Promoter Regions, Genetic / genetics
  • Sequence Analysis, DNA
  • Transcription, Genetic / genetics


  • Arabidopsis Proteins
  • DNA Transposable Elements
  • DNA, Bacterial
  • DNA, Complementary
  • DNA, Plant
  • Pac-2 protein, Arabidopsis
  • Plant Growth Regulators
  • Plant Proteins
  • T-DNA

Associated data

  • GENBANK/X96480
  • GENBANK/X96481
  • GENBANK/X96482