Freezing tolerance in strawberry. Molecular mechanisms of freezing tolerance in strawberries: marker development

This project focuses on winter hardiness in cultivated strawberry (Fragaria x ananassa), a crop of major economical and cultural importance in Norway. Grown on ca. 1700 ha, with a yearly first-hand value of 300 million NOK, strawberries suffer from freezing damage each winter, reducing annual yields up to 20 % with yearly losses of at least 40 million NOK. Hedmark University College (HUC), in collaboration with Graminor Breeding Ltd. (GBL) and researchers in Norway and the USA, has identified candidate molecules that must be first validated through functional testing before they can be further developed and implemented as markers that will accelerate traditional, non-transgenic breeding for improved winter survival in strawberries. 

Our observations thus far support the premise that plants can utilize various strategies during acclimation to successfully survive winter, but that the most hardy cultivars are those with a default molecular profile, a "poise," that directs them towards the best of these strategies. The next challenge is to understand both the functional involvement of candidate markers in freezing tolerance and the mechanisms underlying their differential expression. This information will help validate markers that can be developed for use in (non-transgenic) breeding for improved winter hardiness in strawberry. The questions in focus can be formulated in simple terms: 1) Do candidate markers contribute to cold-hardiness, or is the expression simply a consequence of it?  2) Is the mechanism underlying the differential expression primarily genetic or epigenetic? 3) To what extent are pathways governing cold tolerance cross-regulated with the cold-responsive, epigenetically regulated pathways controlling flowering time?

Cold tolerance and early flowering are traits especially relevant to plant production in Norway, affecting adaptation to freezing temperatures during the dark days of winter and to long days and short growing seasons at high latitudes during summer. Exploring these traits in strawberry, both as a model for perennials and polyploids, will provide useful information for breeding programs of other cultivated species in Norway, especially those within the Rosaceae, like apples, plums and cherries, but will also be relevant for hexaploid wheat, an important cereal grain, and tetraploid red clover, an attractive forage crop.

This project integrates molecular biology, genetics, epigenetics, proteomics, plant physiology and bioinformatics. In addition to Professor Robert Wilson and Associate Professor Wenche Johansen (HUC), collaborators in Norway are located at GBL (Muath Alsheikh), Bioforsk (Jahn Davik), the Norwegian University of Life Sciences (NMBU; Odd Arne Rognli) and the University of Oslo (UiO; Paul Grini). International collaborators include Indiana University-Purdue University Indianapolis (IUPUI; Stephen K. Randall) and the Univ. of Helsinki (UH; Timo Hytönen). The project also utilizes two national technology platforms, the Norwegian Sequencing Centre (NCS, Oslo) and the Centre for Integrative Genetics (CIGENE, Ås).

References

  1. Davik J, Daugaard, H. & Svensson, B. (2000) Strawberry Production in the Nordic Countries. Advances in Strawberry Research 19: 13-18
  2. Davik J, Koehler G, From B, Torp T, Rohloff J, Eidem P, Wilson RC, Sonsteby A, Randall SK, Alsheikh M (2013) Dehydrin, alcohol dehydrogenase, and central metabolite levels are associated with cold tolerance in diploid strawberry (Fragaria spp.). Planta 237: 265-277
  3. Koehler G, Wilson RC, Goodpaster JV, Sonsteby A, Lai X, Witzmann FA, You J-S, Rohloff J, Randall SK, Alsheikh M (2012) Proteomic Study of Low-Temperature Responses in Strawberry Cultivars (Fragaria x ananassa) That Differ in Cold Tolerance. Plant Physiology 159: 1787-1805
  4. Rohloff J, Kopka J, Erban A, Winge P, Wilson RC, Bones AM, Davik J, Randall SK, Alsheikh MK (2012) Metabolite profiling reveals novel multi-level cold responses in the diploid model Fragaria vesca (woodland strawberry). Phytochemistry 77: 99-109
  5. Koehler G, Randall SK, Wilson RC, WInge P, Rohloff J, Alsheikh M (2012) Molecular cold responses for two strawberry cultivars: Comparison of proteomic and microarray analysis. Acta Horticulturae 929: 73-79
  6. Rohloff J, Kopka J, Bones AM, Winge P, Wilson R, Erban A, Sparstad T, Randall SK, Jørstad TS, Davik J, Alsheikh M (2009) Metabolic, Transcriptional, and Proteomic Profiling of Cold Response in Fragaria vesca. Acta Horticulturae 842: 785-788