Genome-wide analyses of the transcriptomes of salicylic acid-deficient versus wild-type plants uncover Pathogen and Circadian Controlled 1 (PCC1) as a regulator of flowering time in Arabidopsis

Plant Cell Environ. 2010 Jan;33(1):11-22. doi: 10.1111/j.1365-3040.2009.02045.x. Epub 2009 Sep 23.

Abstract

Salicylic acid (SA) has been characterized as an activator of pathogen-triggered resistance of plants. SA also regulates developmental processes such as thermogenesis in floral organs and stress-induced flowering. To deepen our knowledge of the mechanism underlying SA regulation of flowering time in Arabidopsis, we compared the transcriptomes of SA-deficient late flowering genotypes with wild-type plants. Down- or up-regulated genes in SA-deficient plants were screened for responsiveness to ultraviolet (UV)-C light, which accelerates flowering in Arabidopsis. Among them, only Pathogen and Circadian Controlled 1 (PCC1) was up-regulated by UV-C light through a SA-dependent process. Moreover, UV-C light-activated expression of PCC1 was also dependent on the flowering activator CONSTANS (CO). PCC1 gene has a circadian-regulated developmental pattern of expression with low transcript levels after germination that increased abruptly by day 10. RNAi plants with very low expression of PCC1 gene were late flowering, defective in UV-C light acceleration of flowering and contained FLOWERING LOCUS T (FT) transcript levels below 5% of that detected in wild-type plants. Although PCC1 seems to function between CO and FT in the photoperiod-dependent flowering pathway, transgenic plants overexpressing a Glucocorticoid Receptor (GR)-fused version of CO strongly activated FT but not PCC1 after dexamethasone treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • DNA-Binding Proteins / metabolism
  • Flowers / genetics
  • Flowers / growth & development*
  • Flowers / metabolism
  • Gene Expression Profiling*
  • Gene Expression Regulation, Plant
  • Genome, Plant
  • Oligonucleotide Array Sequence Analysis
  • Photoperiod
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / growth & development
  • Plants, Genetically Modified / metabolism
  • RNA Interference
  • RNA, Plant / genetics
  • Salicylic Acid / metabolism*
  • Salicylic Acid / pharmacology
  • Transcription Factors / metabolism
  • Ultraviolet Rays

Substances

  • Arabidopsis Proteins
  • CONSTANS protein, Arabidopsis
  • DNA-Binding Proteins
  • FT protein, Arabidopsis
  • PCC1 protein, Arabidopsis
  • RNA, Plant
  • Transcription Factors
  • Salicylic Acid