USING FUNCTIONAL AND APPLIED GENOMICS TO IMPROVE STRESS AND DISEASE RESISTANCE IN FRUIT TREES
Location: Appalachian Fruit Research Laboratory: Innovative Fruit Production, Improvement and Protection
Title: SUBTRACTIVE/SUPPRESSIVE HYBRIDIZATION ANALYSIS OF GENES REGULATED BY LOW TEMPERATURE AND SHORT PHOTOPERIOD IN PEACH BARK
Submitted to: International Meeting on Plant and Microbe Adaptations to Cold
Publication Type: Abstract Only
Publication Acceptance Date: February 7, 2006
Publication Date: May 16, 2006
Citation: Bassett, C.L., Wisniewski, M.E., Artlip, T.S., Norelli, J.L., Renault, J., Farrell, Jr., R.E. 2006. Subtractive/suppressive hybridization analysis of genes regulated by low temperature and short photoperiod in peach bark. International Meeting on Plant and Microbe Adaptations to Cold. p. 45.
In response to environmental cues, plants undergo changes in gene expression that result in the up- or down-regulation of specific genes. To identify genes in peach (Prunus persica [L.] Batsch.) trees whose transcript levels are specifically affected by low temperature (LT) or short day photoperiod (SD), we have created suppression subtractive hybridization (SSH) libraries from bark tissues sampled from trees kept at 5 C and 25 C under short day (SD) photoperiod or simulated long day (LD) via the use of a night break (NB) interruption during the dark period of the SD cycle. Sequences expressed in forward and reverse subtractions using various subtracted combinations of temperature and photoperiod treatments were cloned, sequenced, and identified by BLAST and ClustalW analysis. Low temperature treatment resulted in the up-regulation of a number of cold-responsive and stress-related genes, and suppression of genes involved in "housekeeping" functions, e.g. cell division and photosynthesis. Some stress-related genes not observed to be up-regulated under LT were increased in response to SD treatments. Comparison of the patterns of expression as a consequence of different temperature and photoperiod treatments allowed us to determine the qualitative contribution of each treatment to the regulation of specific genes. As an example of a more in-depth description of one of the genes identified in this study, we report on a new, low-temperature-regulated dehydrin, PPDHN3, which has strong similarity to ERD10 and COR47. Two dehydrin genes from peach bark differentially regulated by low temperature and water deficit have been previously described. PPDHN3 has a degenerate Y-like domain, an S domain and two K segments. In comparison with other woody plants, it is most closely related to birch and poplar dehydrins. One unusual feature of PPDHN3 is the presence of four cysteine residues; with a few exceptions, most dehydrins lack cysteine. Analysis by programs that predict intramolecular cystine bridges did not find evidence for their existence in PPDHN3. Additional detailed analyses of the novel genes identified in this study will lead to a more complete understanding of how woody plants respond to different abiotic signals in their environment.