Proteomics of Cold Acclimation in Zoysaigrass.

Zoysiagrass (Zoysia spp.) are warm season perennial turfgrasses primarily grown in the southern and transition zones of the United States. They are geographically limited in their use because of a relative lack of winter hardiness.  Varying levels of winter injury have been observed among zoysiagrass genotypes and cold-acclimation has been shown to have a significant effect on winter injury in these species. An understanding of the physiological changes that zoysiagrass undergoes during cold acclimation may shed light on phenotypic traits useful in selection of more cold tolerant varieties. To investigate the relationship between cold acclimation, protein expression,  and freeze tolerance in zoysiagrasses, selected cultivars with a reported range of freeze susceptibility, ‘Meyer’, ‘JaMur’, and ‘Victoria’, were exposed to cold-acclimation and non-acclimation treatments in a randomized complete block design with three replications. Cold-acclimated and non-acclimated conetainers of ‘Meyer’, ‘JaMur’, and ‘Victoria’ were evaluated in four controlled freezing chambers reaching -6, -8, -10, and -12ºC to compare the impact of cold acclimated and non-acclimated treatments on freeze tolerance.  Additionally, crown tissue was harvested for proteomic analysis from both cold-acclimated and non-acclimated conetainers of ‘Meyer’ and ‘Victoria’ after the four week acclimation period.  Mass spectroscopy was used to evaluate these tissues for differentially expressed proteins between cultivars and acclimation treatments.  Functions  of these proteins as well as correlations between protein accumulation and plant survival in freezing test was evaluated in order to identify their potential roles in freezing survival.