밀 품종들의 내한성에 대한 과산화수소 처리의 효과

다국어 초록 (Multilingual Abstract)

Due to global warming and unstable climatic condition, environmental damage like freezing, drought and flooding to crops is increasing. Wheat, a major staple crop in the world, is often subjected to low temperature and drought stress during overwintering which results in the reduction of growth and yield in early- and late-spring. Because needs and consumption for Korean domestic wheat is steadily increasing, drought tolerance is one of important traits for improving wheat production. Due to low level of irrigation system in most wheat fields of Korea, improved drought tolerance is necessary for stable wheat production. In this study, hydrogen peroxide was applied to wheat leaves for improving drought tolerance and the multi-faced effects of hydrogen peroxide on wheat seedlings were traced in physiological and proteomic changes. Eight Korean wheat cultivars (cv. Geumgang, Baekjung, Sugang, Yeonbaek, Uri, Jeokjung, jogkeong and Hanbaek) showing different drought susceptibility were used for the experiment. Based on the survival rate under drought condition, cv. Sugang, Uri and Hanbaek were extremely susceptible to drought, especially Uri was the most susceptible. On the other hands, cultivar Yeonbaek was the most tolerant among cultivars tested in the experiment. Responses to drought were examined with 3-leaf old seedlings (grown for two weeks) by limiting the watering. The tolerant cultivar Yeonbaek showed little reduction in dry weight (65% of the control) as compared to untreated control (0.425g). The most sensitive cultivar Uri showed great reduction in dry weight (34% of the control) as compare to the control (0.600g). Seeds of eight wheat cultivars were subjected to low water potential from 0 to -2.0 bar with or without hydrogen peroxide (20mM). Cultivar Jogyeong, Uri, Sugang, and Geumgang were classified as drought susceptible cultivars and cv. Jeokjung, Hanbaek, Baekjung, and Yeonbaek were as tolerant cultivars based on germination percentage at -2.0 bar. Hydrogen peroxide ameliorated the drought injury to seed germination with different degree according to cultivar showing greater effect on susceptible cultivars. Germination percentage of susceptible cultivars, Geumgang and Uri, were highly improved from 15 and 33.3% at -2.0 bar to 38.3 and 55% by 20mM H2O2 treatment, respectively. On the other hands, tolerant Baekjung and Yeonbaek showed slight increase of germination percentage from 91 and 85% to 98 and 98% by H2O2 treatment, respectively. Hydrogen peroxide treatment promoted plumule elongation in susceptible cultivars. Plumule extrusion that were not observed at -2.0 bar occurred by H2O2 treatment in Jogyeong and Uri. Antioxidant activity (by DPPH test) in cv. Yeonbaek and Uri were higher hydrogen peroxide treatment than control. But the concentration of hydrogen peroxide did not show difference. In the wheat seedlings, hydrogen peroxide treatment(foliar spray) delayed foliar wilting during early drought stress. H2O2-sprayed seedling showed greater plant height and lead width than DW-sprayed seedlings. Proteomic analysis showed more increased expressions of proteins related photosynthesis, carbon fixation and energy metabolisms under drought condition in tolerant cultivar Yeonbaek than susceptible Uri. Therefore, the higher expression level of the above identified proteins of tolerant cultivar reflected the less reduction in primary metabolisms that result in less reduction in growth of tolerant cultivar under drought condition. Higher expression of heat-shock proteins and antioxidant protein (2-cys peroxiredoxin BAS1) in hydrogen peroxide treated tolerant plants was observed. This result means that the increased antioxidative activity is a key event in wheat plant under drought condition and foliar applied hydrogen peroxide mitigates the oxidative stress caused by drought.

목차 (Table of Contents)

• Ⅰ. 서언 1
• Ⅱ. 연구사 3
• Ⅲ. 재료 및 방법 7
• Ⅳ. 결과 및 고찰 11
• Ⅴ. 요 약 31
• 인용문헌 33