The CArG-box located upstream from the transcriptional start of wheat vernalization gene VRN1 is not necessary for the vernalization response

J Hered. May-Jun 2009;100(3):355-64. doi: 10.1093/jhered/esp002. Epub 2009 Feb 27.

Abstract

In diploid wheat (Triticum monococcum), and likely in other Triticeae species, the VRN1 gene is essential for the initiation of the reproductive phase, and therefore, a detailed characterization of its regulatory regions is required to understand this process. A CArG-box (MADS-box-binding site) identified in the VRN1 promoter upstream from the transcription initiation site has been proposed as a critical regulatory element for the vernalization response. This hypothesis was supported by the genetic linkage between CArG-box natural deletions and dominant Vrn1 alleles for spring growth habit and by physical interactions with VRT2, a MADS-box protein proposed as a putative flowering repressor regulated by vernalization. Here, we describe a T. monococcum accession with a strong vernalization requirement and a 48-bp deletion encompassing the CArG-box in the VRN1 promoter. Genetic analyses of 2 segregating populations confirmed that this VRN1 allele is completely linked with a strong winter growth habit (vrn-A(m)1b). Transcript levels of the VRN1 allele with the 48-bp deletion were very low in unvernalized plants and increased during vernalization to levels similar to those detected in other wild-type vrn-A(m)1 alleles. Taken together, these results indicate that the CArG-box found upstream of the VRN1 transcription initiation site is not essential for the vernalization response.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alleles
  • Base Sequence
  • Crosses, Genetic
  • Genes, Plant*
  • Models, Genetic
  • Molecular Sequence Data
  • Plant Proteins / genetics*
  • Promoter Regions, Genetic*
  • Sequence Analysis, DNA
  • Transcription Factors / genetics*
  • Transcription Initiation Site
  • Triticum / genetics*

Substances

  • Plant Proteins
  • Transcription Factors