An ER-targeted calcium-binding peptide confers salt and drought tolerance mediated by CIPK6 in Arabidopsis

Planta. 2012 Mar;235(3):539-52. doi: 10.1007/s00425-011-1522-9. Epub 2011 Oct 5.


Different plant organelles have high internal stores of Ca(2+) compared to the cytoplasm and could play independent roles in stress responses or signal transduction. We used a GFP fusion with the C-domain of calreticulin, which shows low-affinity, high capacity Ca(2+) binding in the ER, as a calcium-binding peptide (CBP) to specifically increase stores in the ER and nucleus. Despite the presence of a signal sequence and KDEL retention sequence, our work and previous studies (Brandizzi et al. Plant Journal 34:269-281, 2003) demonstrated both ER and nuclear localization of GFP-CBP. Under normal conditions, GFP-CBP-expressing lines had ~25% more total Ca(2+) and higher levels of chlorophyll and seed yield than wild type and GFP controls. CBP-expressing plants also had better survival under intermittent drought or high salt treatments and increased root growth. One member of the CIPK (calcineurin B-like interacting protein kinase) gene family, CIPK6, was up-regulated in CBP-expressing plants, even under non-stress conditions. A null mutation in cipk6 abolished the increased stress tolerance of CBP-transgenic plants, as well as the CBP-mediated induction of two stress-associated genes, DREB1A and RD29A, under non-stress conditions. Although this suggested that it was the induction of CIPK6, rather than localized changes in Ca(2+), that resulted in increased survival under adverse conditions, CIPK6 induction still required Ca(2+). This work demonstrates that ER (or nuclear) Ca(2+) can directly participate in signal transduction to alter gene expression. The discovery of a method for increasing Ca(2+) levels without deleterious effects on plant growth may have practical applications.

Publication types

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

MeSH terms

  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Calcium / metabolism
  • Chlorophyll / metabolism
  • Droughts*
  • Endoplasmic Reticulum / metabolism*
  • Gene Expression Regulation, Plant
  • Immunoblotting
  • Peptides / genetics
  • Peptides / metabolism*
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Plant Roots / drug effects
  • Plant Roots / genetics
  • Plant Roots / metabolism
  • Plants, Genetically Modified / drug effects
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / metabolism
  • Potassium / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Salts / pharmacology
  • Sodium / metabolism


  • Peptides
  • Plant Proteins
  • Salts
  • Chlorophyll
  • Sodium
  • Potassium
  • Calcium