Evaluation Of Resistance To Two Main Diseases In Wheat Germplasm Resources And Study On Physiological Characteristics Of Resistance

Wheat powdery mildew and stripe rust are two major diseases in wheat areas in China,which threaten the growth and development of wheat and affect the yield of wheat.At present,the most economical,safe and effective way is to breed disease-resistant varieties.Collection,excavation and innovative utilization of excellent germplasm resources are the key techniques to continuously improve the level of resistance in wheat.At present,the evaluation of disease resistance of wheat germplasm resources mainly focuses on the identification of disease resistance of a single disease,but due to the change of climatic conditions,multiple diseases often occur at the same time,it is particularly important to screen germplasm resources with multiple resistance.At the same time,it is very important to understand the physiological characteristics of interaction between wheat and pathogens for wheat breeding of high yield and disease resistance.1.The resistance of 238 wheat varieties（lines）mainly from Huanghuai wheat region and 32 wheat varieties abroad were evaluated at seedling stage and the resistance genes were detected by using mixed strains of wheat powdery mildew.The results of resistance identification at seedling stage showed that among the 238 wheat materials in huanghuai wheat region,170 were susceptible varieties（lines）and 60were resistant varieties（lines）,accounting for 71.4%and 25.2%respectively.The results of molecular markers showed that Pm2 was detected in 3 materials,Pm21 was detected in 4 materials,and Pm24 was detected in 15 materials,accounting for 1.3%,1.7%and 6.3%respectively.Only dong1-32 and Shan 452 of Pm2 and Pm24 were resistant to Blumeria graminis.Among 32 wheat varieties abroad,7 showed disease resistance and 25 showed disease susceptibility,but no Pm2,Pm21 and Pm24 were detected.The above results showed that wheat varieties（lines）in huang-huai wheat region performed well in resistance to powdery mildew at seedling stage,and the proportion of Pm2,Pm21 and Pm24 was not high,and the resistance of Pm2 and Pm24 to powdery mildew was lost in this region,these resistant varieties（lines）may contain other known or unknown resistance genes（combinations）,which provide abundant materials for breeding resistant varieties and mining new resistance genes,while only 7 out of 32 foreign wheat varieties have resistance,and there were no Pm2,Pm21 and Pm24,which could be used for breeding.2.Wheat-haynaldia villosa 6VS/6AL translocation line 92R137 and wheat variety Yangmai 5 susceptible to powdery mildew were inoculated with mixed strains of powdery mildew of wheat,and uninoculated materials were used as blank control,the contents of chlorophyll,hydrogen peroxide（H₂O₂）,proline（Pro）,reduced ascorbic acid and reduced Glutathione in 0-10d wheat leaves,and the activities of seven enzymes including catalase,peroxidase,superoxide dismutase,peroxidase,glutathione reductase,mitochondrial（GR）and MDHAR were analyzed,in order to reveal the physiological mechanism of wheat resistance to powdery mildew.The results showed that the chlorophyll contents of 92R137 and Yangmai 5 were significantly decreased after inoculation with the mixed strains of powdery mildew,and the Pro contents of 92R137 and Yangmai 5 were higher after inoculation than before inoculation After inoculation,the content of H₂O₂in 92R137 increased,the activity of CAT increased first and then decreased,the activity of POD increased gradually,but the activity of SOD did not change significantly,the content of H₂O₂decreased continuously,the activity of CAT and Pod increased first and then decreased,the activity of SOD increased gradually.Therefore,the changes of activities of defense enzymes such as CAT,POD and SOD played an important role in wheat resistance to powdery mildew infection.The change of H₂O₂content may be related to the disease resistance of wheat,and the change of H₂O₂content in wheat is the result of multi-enzymes.There were no significant changes in the ascorbic acid-Glutathione cycle,and the ascorbic acid-Glutathione cycle was not associated with the resistance of wheat to powdery mildew.3.88 cultivars was evaluated at seedling stage and the resistance genes of stripe rust were detected by inoculation of stripe rust dominant race CYR 31.The results showed that among the 88 materials,35 were high resistant,14 were medium resistant,9 was medium sensitive and 30 were high sensitive,accounting for 39.8%、15.9%、10.2%and 34.1%respectively.Jimai 7,mianmai 39,xiaoyan,mianmai 48 and luomai9 might contain the Yr26 gene,accounting for 5.7%of the total materials.4.The results of seedling resistance identification showed that wanmai 33,yangmai 12,yangmai17,liangxing 99,yannong 12,xiaoyan 4,shan 452,xiaoyan,mianmai 43,chuannong 16,9871,jimai 36,weimai 22,shimai 14,07G231,liangxing66,lumai 22,mianmai 45,mianmai 37,jimai 22 and 213 are resistant to both diseases at seedling stage,and can be used as resistant parents in disease resistance breeding.