|Artlip, Timothy - Tim|
Submitted to: Tree Genetics and Genomes
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/16/2007
Publication Date: 6/1/2008
Citation: Renaut, J., Wisniewski, M.E., Bassett, C.L., Artlip, T.S., Henry-Michel, C., Witters, E., Laukens, K., Hausman, J. 2008. Quantitative proteomic analysis of short photoperiod and low-temperature responses in bark tissues of peach (Prunus persica L. Batsch). Tree Genetics and Genomes. DOI 10:1007/s11295-008-0134-4. Interpretive Summary: Millions of dollars are lost annually by the fruit industry due to the adverse effects of environmental stress on tree vigor, longevity, and crop load. In particular, late spring frosts can result in the partial or entire loss of crops, and severe midwinter temperatures can result in the loss of entire orchards. Resistance to freeze injury is a complex trait that involves numerous genes that dramatically change the physiology of the plant in order to allow it to withstand freezing temperatures and the presence of ice within its tissues. There is also growing recognition that some of the adaptation to freezing temperatures may be regulated after genes are transcribed and involve changes in protein biochemistry. In order to better understand how trees cold acclimate, we have utilized a new technology called differential in-gel electrophoresis (2D- DiGE) to conduct a global analysis of protein changes in response to short days and low temperature in bark tissues of peach. This approach is referred to as proteomics. DiGE technology greatly increases the efficiency and reliability of proteomic studies while enhancing the ability to discern quantitative differences in levels of proteins between samples. In our study, peach trees were exposed to combinations of short day (SD) and/or low temperature (LT) treatments. Analysis of the data indicated that 824 proteins were reproducibly present on the 2-D gels, and 114 of these proteins either increased or decreased in response to the individual treatment factors (SD and LT) or a combination of SD and LT. Fifty-seven of the proteins were positively identified by mass spectrometry. The identified proteins included ones involved in stress response, carbohydrate metabolism, defense mechanisms, energy transport, and organization of the cytoskeleton. These results provide the beginning of an attempt to develop a full catalogue of proteins in fruit trees that are involved in resistance to environmental stress. Further proteomic studies will be conducted on different tissues and different fruit crops. This information will be used to identify novel approaches to alleviating the negative impact of low-temperature stress on fruit tree health and productivity.
Technical Abstract: In the Northern hemisphere, under temperate climate, woody plants survival is determined by the combination of different factors, including the lowering of temperatures and the shortening of photoperiod. These two factors (5 deg C and short photoperiod) were used in combination to study the variations in abundance of the bark proteome of one-year-old seedlings of peach (Prunus persica (L.) Batsch) kept in growth chambers. The use of recent techniques such as quantitative proteomics, a gel-based approach involving the labelling of proteins with different fluorescent dyes, allows getting a wider and comprehensive approach of proteome changes occurring during cold acclimation or dormancy in peach bark. From the proteomic results, we were able to select differentially expressed proteins and to assign them to a class of either 'temperature-responsive' or 'photoperiod-responsive' proteins. The most affecting factor appeared to be the lowering of temperature, while the combination of temperature and variation of photoperiod was shown to act synergistically and additively as some proteins presented a drastic change in their abundances in these conditions. Fifty-seven of these proteins were identified by mass spectrometry. It includes proteins involved in carbohydrate metabolism (e.g. enolase, malate dehydrogenase, etc.), defence mechanisms (e.g. dehydrin, HSPs, PR-proteins), energy production and electron transport (e.g. ATP synthases, lyases), and cytoskeleton organisation (e.g. tubulins, actins). The information given by the analysis of the proteome will be presented and discussed as function of the two factors affecting its abundance.