Genetic Diversity and Physiological Response to Drought Stress of Chamaecyparis obtuse from Six Geographical Locations

Water deficit is a critical factor obstructing the growth and survival of plant. Therefore, researchers have been trying to develop drought-resistant varieties. To find indicators of drought stress-tolerance of cypress (Chamaecyparis obtusa), we analyzed the response of cypress seedlings from six provenances of Korea (Jeju, Suwon, Seoul, Seongnam, Yong-in, and Osan) to drought stress. Additionally, the genetic diversity of C. obtusa from the six provenances were determined using microsatellite markers. We confirmed that populations from Suwon and Seongnam were relatively separated from other populations through genetic distance and cluster analysis. We examined their physiologic and metabolic responses after drought treatment for five weeks. Almost all of the cypress seedlings showed a reduced shoot growth rate under drought treatment compared to controls. In addition, temperature of drought treated cypress seedling leaves was 1.2-2℃ higher than that of the controls. Almost all of the drought stress-treated cypress showed increased carbon metabolite contents and pigments. In particular, the cypress seedlings from Osan showed the highest increase in all of the measured metabolites. Therefore, it is suggested that the seedlings from Osan are susceptible to drought stress. Conversely, the seedlings from Jeju, Suwon, and Yong-in showed a lower sensitivity to drought treatment. These results indicate that the cypress trees from the six provenances have a different response to drought stress. In addition, it is confirmed that previously identified indicators of drought stress, especially those that measure total soluble sugar, carotenoid, and H2O2, can be used in the selection of drought resistance cypress. These findings may useful in studies concerned with the metabolic and physiological responses of young cypress to drought.