Proteome dynamics of cold-acclimating Rhododendron species contrasting in their freezing tolerance and thermonasty response

Authors: DIE, JOSE - US Department Of Agriculture (USDA); ARORA, RAJEEV - Iowa State University; Rowland, Lisa

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2017
Publication Date: 5/23/2017
Citation: Die, J.V., Arora, R., Rowland, L.J. 2017. Proteome dynamics of cold-acclimating Rhododendron species contrasting in their freezing tolerance and thermonasty response. PLoS One. 12(5): e0177389.

Interpretive Summary: Rhododendron is a major nursery crop widely grown throughout the United States and is a relative of the fruit crops, blueberry, cranberry, and lingonberry. Similar to these fruit crops where cold damage can reduce yield, extreme cold temperatures in winter and early spring can cause damage to Rhododendron flower buds and flowers and prevent production in some parts of the country. Additional knowledge is required to better understand how plants respond to cold temperatures and survive freezing conditions. Rhododendron is a useful model because some types of rhododendron can survive extremely low winter temperatures whereas other members are far less winter hardy. We conducted experiments to identify compounds that Rhododendron plants differing in cold hardiness levels produce under cold weather conditions. We identified approximately 75 proteins that plants produced in response to cold temperature and determined the function of these proteins in the plant. These results were compared to proteins that we previously identified in blueberry under cold conditions. This information will be used by scientists to further characterize cold hardiness and develop plants that are more tolerant to freezing temperatures.

Technical Abstract: In the present study we used 2D-DIGE technique to document the Rhododendron proteome during the seasonal development of cold hardiness. We selected two genotypes with different cold hardiness levels. This enabled us to perform comparative analysis of their proteome profiles and screen differentially expressed proteins closely associated with the target phenotype. Our objectives were to (1) analyze changes in protein composition in non-acclimated vs. acclimated plants from a cold-hardy cultivar and (2) identify proteins that are associated with the acquisition of superior freezing tolerance by comparing the cold acclimated proteomes in two genetic backgrounds. Cold acclimation is a metabolically active process. Our results suggest that production of high levels of energy, osmotic regulation, desiccation tolerance, regulation of biosynthesis of several stress-related metabolites, cell wall remodeling and photosynthesis adjustment are some of the key components of cold acclimation in rhododendron. Differences in freezing tolerance between genotypes can probably be attributed to differential ability to modulate some of the proteins involved in these functions, but also to higher levels of some constitutively expressed protective proteins that may be required to overcome freeze damage.