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: Comparative expression profiling and transcript initiation of three peach dehydrin genes
Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 16, 2009
Publication Date: April 10, 2009
Citation: Bassett, C.L., Wisniewski, M.E., Artlip, T.S., Richart, G., Norelli, J.L., Farrell, Jr., R.E. 2009. Comparative expression profiling and transcript initiation of three peach dehydrin genes. Planta. 230:107-118.
Interpretive Summary: Plants have learned to adapt to harsh environmental conditions, such as freezing temperatures or water shortages, by expressing a variety of genes that provide protection against these extremes. Elevated expression of a group of genes known as 'dehydrins' has been shown to occur when plants are exposed to cold, drought, and high salt conditions. Since dehydrins all have common features, observed differences in expression in response to adverse weather conditions must lie in how the genes are regulated. To understand more about how dehydrins are controlled in woody plants, we have isolated three genes encoding dehydrins from peach. Comparison of the regulatory regions of these genes with each other and with similar genes from other plants, like poplar, indicates that each region has different combinations of DNA sequences that interact with special proteins to influence expression. Information from these studies will help us find ways to elevate expression of these genes before inclement weather strikes; therefore, providing protection before significant harm is done to the plant.
One way plants respond to abiotic stress is to increase the expression of defense proteins. The dehydrin family of genes encodes proteins with demonstrated cryoprotective and antifreeze activity, and they respond to a variety of abiotic stress conditions that have dehydration as a common component. Two dehydrins from peach have been previously described, one of which is associated with cold responsiveness and the other of which responds to water deprivation. Here, we describe the characterization of a third dehydrin, PpDhn3, from peach bark isolated by its response to low temperature. The expression of all three dehydrin genes was profiled by semi-quantitative reverse transcription (RT) PCR, and transcript initiation was mapped for all three genes using the RLM-5'RACE technique. The majority of PpDhn3 transcripts from bark collected in December or July, as well as, transcripts from developing fruit, initiated at a single site. Although, most of the PpDhn1 transcripts initiated at a similar position, those from fruit sampled 7 days after full bloom initiated much further upstream of the consensus TATA box. Likewise, bark and fruit transcripts encoding PpDhn2 initiated ca. 30 bases downstream of a consensus TATA box; however, transcripts from ripe fruit all initiated upstream. Ripe fruit transcripts of PpDhn2 contain a 5' UTR intron which is predicted to add some 34 amino acids to the N terminal methionine of the cognate protein when properly processed. These results reveal a new, unexpected level of gene regulation contributing to the overall expression pattern of peach dehydrins.