| The common16Kentucky Bluegrass in northern were used as materials in this study. After heat stress, turfgrass quality, relative electronic leakage, chlorophyll content, soluble protein content and leaf relative water content were performed to determine heat resistance on16Kentucky Bluegrass. And then two cultivars with significantly different heat-resistance were selected to study the change of physiological and biochemical factors and protein expression associated with heat tolerance. These works explored the physiological mechanisms of heat resistance and provided a theoretical basis for breeding new cultivars of Kentucky Bluegrass with a better heat-resistance characteristics. The results as follows:1. In a38/30℃(day/night) growth condition, as heat stress maintained, leaf relative conductivity was increased, but the turf quality, the chlorophyll content and leaf relative water content were reduced by the maintained heat stress during the whole process. However, the soluble protein exhibited firstly a decrease, then an increase. The result by a cluster analysis shown that ’EverGlade’,’Award’,’Midnight’ and ’Brooklawn’ had the highest heat tolerance.2. Membrane lipid peroxidation on Kentucky Bluegrass was intensified during heat stress. Meanwhile, the activity of antioxidant enzyme and its isoenzymes were changed. Compared with heat-sensitive cultivars,’EverGlade’ had a lower content of MDA and higher antioxidant enzyme activity. This response indicates a good ROS scavenging ability in heat-tolerant cultivars. The expression of some isozymes were inhibited while some were promoted during heat stress. The heat-tolerant cultivars had more and stronger isozymes than heat-sensitive cultivars.3. At the end of heat stress, the souble protein and free amino acids content of Kentucky Bluegrass were decreased while the contents of proline were increased with some days treatment by high temperature. During the treatment period, the content of the souble protein and free amino acids in ’EverGlade’ were higher than in ’Kenblue’ but the proline content was lower.4. By the end of heat stress treatment, the content of ABA and IAA were both decline in two cultivars, but the’EverGlade’was superior to ’Kenblue’ in the whole period. The dynamic balance of IAA/ABA was break under heat stress, but the important role of ABA and IAA play in physiology were not affected.5. Results from SDS-PAGE showed that synthesises of some protein were inhibited while some new protein were synthesized during heat treatment. The new synthesized proteins were earlier detected in ’EverGlade’ than in ’Kenblue’. Therefore, the synthesis of additional proteins under heat stress might be assoeiated with heat tolerance. |
