Proteomic Response to Drought Stress and Recovery in Turfgrass Leaves.

Drought is one of the major limiting factors of plant production worldwide. Understanding genetic variations and mechanisms in turfgrass drought tolerance would facilitate breeding and management programs to improve turf quality under drought stress. The objective of this study was to investigate protein changes in response to drought tolerance in two Kentucky bluegrass (Poa pratensis L.) cultivars. Plants of ‘Brilliant’ and ‘Midnight’ were subjected to drought stress by withholding water for 15 days, and then rewatered for recovery, in growth chambers. The leaves were harvested at 5, 10, and 15 days after drought treatment, and 2 days after rewatering. Midnight maintained higher relative water content and photochemical efficiency, and lower membrane leakage than Brilliant at 15 d of drought stress. Proteins were extracted and separated by difference gel electrophoresis. Seventy leaf protein spots were differentially accumulated in response to drought stress in at least one cultivar. The sequences of 66 protein spots were analyzed using mass spectrometry.  The results revealed that Brilliant exhibited more severe protein degradation than Midnight. Heat stress induced expression of several heat shock proteins (HSPs) in both cultivars, but the induction occurred earlier in Midnight than in Brilliant. The results suggested that better drought tolerance in the Kentucky bluegrass was associated with induction of HSPs during the early phase of drought stress and maintenance of higher protein content and less severe protein degradation during prolonged periods of drought stress.