Exploiting the wild crucifer Thlaspi arvense to identify conserved and novel genes expressed during a plant’s response to cold stress

Abstract

Thlaspi arvense, a wild species from the Brassicaceae family, was shown to have a higher level of freezing tolerance than either of its close relatives, the model plant Arabidopsis thaliana or the crop Brassica napus (canola). Over 600 clones were sequenced from a subtractive cDNA library generated from cold treated T. arvense tissue, establishing that T. arvense shared significant sequence identity with both A. thaliana and B. napus (90-92%). In light of the strong sequence similarity between T. arvense and A. thaliana and to exploit the available genomics resources for Arabidopsis, the efficacy of using long 70 mer oligonucleotide whole genome Arabidopsis microarrays was tested for T. arvense. Gene expression in T. arvense leaf tissue during the very early stages of cold acclimation (or cold stress) was assayed at three time points and compared to an untreated control. This analysis highlights some of the difficulties and benefits of using cross-species microarray analysis. The data suggested that T. arvense responds in a similar fashion to cold stress as the model plant A. thaliana. However, for a number of genes quantitative differences in the level and timing of expression were identified. One of the most notable differences suggested that sulphur assimilation leading to the increased production of the methyl donor S-adenosyl-methionine was playing a role in the response of T. arvense to cold stress.

A Comparison of Leaf and Petal Senescence in Wallflower Reveals Common and Distinct Patterns of Gene Expression and Physiology

“…This compares favorably with other studies using species taxonomically related to Arabidopsis (e.g. in Thlaspi arvense arrays, only 31% of probes cross-hybridized to Arabidopsis [Sharma et al, 2007]). Likewise, for the six wallflower genes on the array, for which the closest Arabidopsis homolog was also included on the array and data were available from the Affymetrix experiments, there was a very high level of agreement.…”

Comparative genome organization reveals a single copy of CBF in the freezing tolerant crucifer Thlaspi arvense

“…It has been reported that T. arvense can survive winters on the Canadian Prairies and in Alaska with temperatures reaching lows of -30°C (Best and Mcintyre 1975;Klebesadel 1969). The freezing tolerance of T. arvense has been confirmed in the laboratory and after 3 weeks of cold acclimation was shown to exceed that of A. thaliana by 7°with a recorded LT 50 of -16.8°C (Sharma et al 2007). The smaller genome size of T. arvense, compared to its relative, the crop Brassica napus (canola), and the documented ability of this plant to survive sub-optimal temperatures make it a candidate as a model crucifer for use in studying the mechanisms controlling enhanced stress tolerance, particularly freezing tolerance.…”

“…Freezing tolerance of the transgenic and wild type control were assayed using electrolyte leakage to determine the LT 50 as described in Sharma et al (2007).…”

Physiological and molecular changes in plants grown at low temperatures

“…They are synthesized via the phenylpropanoid pathway, which is controlled by key enzymes, including phenylalanine ammonia-lyase and chalcone synthase (Sharma et al 2007). Recently, it has been reported that cold stress induces transcriptomic modifications that increase flavonoid biosynthesis, including reactions involved in anthocyanin biosynthesis and the metabolic pathways that supply it (Crifo et al 2011).…”