Metabolic Adjustments of Five Bermudagrass Varieties During Cold-Acclimation and De-Acclimation.

The extent of cultivar metabolic responses to cold acclimation (CA) and de-acclimation (DCA) are most likely related to freezing tolerance and rate of spring green up in bermudagrass (Cynodon spp.), but the underlying mechanisms are not well documented. This study was conducted to characterize photochemical efficiency (PE), total amino acid (AA), proline, and dehydrins protein expression changes during CA and DCA in one ecotype (‘GA ecotype’) and four cultivars (‘Tifway’, ‘Patriot’, ‘Riviera’, and ‘Princess-77’).  Bermudagrasses were subjected to CA (8/4 ºC) for 4 weeks, and then to a series of DCA temperature regimes ranging from 10/5 ºC (day/night) to 26/14 ºC for 12 weeks. Preliminary results showed that PE declined rapidly from 0.72 to 0.08, and abundance of stolon dehydrin (25 kDa), protein, AA, and proline content increased during CA. During DCA at 21/7 ºC, PE recovered to 0.60 after 3 weeks. Concurrently, the abundance of 25 kDa dehydrin, protein, AA, and proline declined. On average, ‘GA ecotype’, ‘Patriot’ and ‘Tifway’ had greater visual quality relative to ‘Riviera’ and ‘Princess-77’ during DCA, which was associated with greater PE and higher AA and proline contents in the stolons.  Rapid metabolic adjustments in parameters such as PE, dehydrins, AA, and proline content during CA and DCA may be considered as biochemical markers for cold hardiness and faster spring greenup of certain bermudagrass cultivars.