Constitutive Freezing Tolerant Mutants in Arabidopsis
Little is known about the signaling cascades by which plants perceive low temperatures and use the information to trigger molecular and biochemical programs leading to increased freezing tolerance. We have developed a Petri dish freezing assay that allows rapid screening of large numbers of M2 plants for mutants which are constitutively freezing tolerant. In this assay, non-acclimated wild-type Arabidopsis thaliana, Columbia exhibited a killing temperature (LT50) of −5.3°C. Two days of acclimation at 4°C brought about a change in LT50 to −12°C. Over 20 independent mutant lines that are freezing tolerant without cold acclimation were obtained by screening approximately 800,000 EMS-mutagenized M2 plants at −8°C. One mutant line, which has a recessive mutation at a locus designated eskimol (esk1), has LT50 of-11.5°C in the absence of acclimation. The esk1 mutant is smaller than WT but in most other aspects the growth and development of these plants are similar to WT. One hypothesis to explain the recessiveness and pleiot-ropic effects of esk1 is that the wild-type ESK1 gene may encode a negative regulator which represses the genetic programs required to withstand freezing at normal growth conditions.
KeywordsMethane Hydrogen Peroxide Maize Agar Proline
Unable to display preview. Download preview PDF.
- Dhindsa RS, Monroy AF, Sangwan V, Kawczynski W, Labbe E (1996) Low temperature signal transduction during cold acclimation. In: This proceedingGoogle Scholar
- Jarillo JA, Leyva A, Salinas J, Martinez-Zapater JM (1989) Low temperature induces the accumulation of alcohol dehydrogenase mRNA in Arabidopsis thaliana, a chilling-tolerant plant. Plant Physiol 101: 833–837Google Scholar
- Levitt J (1980) Responses of Plants to Environmental Stresses, Vol 1. Academic Press, Orlando, FLGoogle Scholar
- Steponkus PL, Uemura M, Joseph RA, Gilmour SJ, Thomashow MF (1996) Constitutive expression of the COR15a gene alters the freezing tolerance of leaves and isolated protoplasts of Arabidopsis thaliana. In: This Proceeding.Google Scholar
- Thomashow MF (1994) Arabidopsis thaliana as a model for studying mechanisms of plant cold tolerance. In: EM Meyerowitz and CS Somerville, eds. Arabidopsis. Cold Spring Harbor Laboratory Press, pp807-834Google Scholar
- Thomashow MF, Stockinger E, Gilmour SJ, Bloksberg L (1996) Regulation of COR gene expression in response to low temperature and drought. In: This ProceedingGoogle Scholar
- Warren G, McKown R, Marin A, Teutonico R (1996) Arabidopsis mutants impaired in freezing tolerance after cold acclimation. In: This ProceedingGoogle Scholar