| Tomatoes(Lycopersicon esculentum Miller)originated in the subtropical region of South America.They are loved by people because of their high nutritional value,good taste,and various eating methods.There are a large number of facilities for tomato cultivation around the world.The large-scale cultivation and production of tomatoes also brought a series of problems,mainly including the limitation of adversity conditions and the prevalence and spread of pests and diseases.Tomato yellow leaf curl virus disease(TYLCVD)is one of the main diseases affecting tomato production.The obvious epidemic characteristics of this disease are fast spread,wide range,and imminent,etc.This has resulted in a large reduction in yields and crop failure in cultivated areas,which has seriously affected the production and quality of tomatoes.The commonly used control measures are chemical measures,but it is easy to cause environmental pollution,pesticide residues and other problems,so the ideal control effect has not been achieved.The top priority is to breed resistant varieties and breeding new varieties of disease resistance is one of the most effective ways to control diseases at present.It has the advantages of green,high efficiency and pertinence.It can fundamentally solve the impact of diseases on tomatoes and has great practical significance for the long-term development of the tomato industry.Usually the breeding of new varieties only depends on the identification of natural inoculation or PCR.The identification method is relatively simple and lacks reliability.Therefore,this study starts from the three aspects of disease resistance phenotype,physiological and biochemical characteristics,and molecular,we used 15 self-breeding infinitely growing tomato materials as test materials,contrast materials include the tomato yellow leaf curl virus resistant variety Qidali and the susceptible variety Money Maker(MM).Through disease investigation,the physiological and biochemical indicators,yellow leaf curl virus-related genes(Ty-1,Ty-2,Ty-3)and expression changes in the leaves of seedlings were investigated,and the changes of resistance in different periods were explored and screened some excellent tomato materials that can resist tomato yellow leaf curl virus disease.Through the analysis of the research results,the main contents are as follows:(1)TYLCV virus detection and resistance evaluation of different tomato materials found viruses were detected in all tomato materials.853,857,867 and Qidali had strong resistance to TYLCV,which showed immunity,and 817 and 842 showed high resistance.The results of the disease survey showed that with the passage of time,in addition to immune and high-resistance materials,the disease rate and disease index of other materials showed an upward trend,and the fastest rising trend was from 20 d to 30 d and peaked at 40 d.At 20 days after inoculation,805,817,819,820,841,and 842 showed high resistance,and 853,857,867,and Qidali showed immunity,proving that they are resistant to tomato yellow leaf curl virus disease in the early stage of infection;30 days after inoculation,the incidence of diseased plants and disease index of susceptible materials increased significantly,and the incidence and disease index of 801,802,806,822,MM were higher,which were significantly different from other materials(P<0.01,P<0.05);at 40 days after inoculation,the diseased plant rate and disease index of most of the susceptible materials increased slowly and stabilized,and the susceptibility situation did not change much from that at 30 days,proving that the disease had fully developed at 40 days.801,802,803,806,822,MM disease rate and disease index reached the peak,the incidence is the most serious,and it is significantly worse than other materials(P < 0.01,P < 0.05),it is a very typical susceptible variety.(2)Studies on disease resistance and physiological and biochemical characteristics show that the antioxidants,defensive enzyme activities,and secondary metabolite contents of 853,857,867,and Qidali in 17 tomato materials were generally higher than those of susceptible materials.Among them,the enzyme activity(SOD)of Qidali,the enzyme activity(CAT)of 867,and the enzyme activity(APX)of 853 are higher and have significant differences compared with other materials(P < 0.05);The defense enzymes(PAL,PPO,POD)activity of 853,857,867 peaked at the beginning of the onset,the peak of enzyme activity of other susceptible materials appeared later.The PAL activity and POD activity of Qidali and the PPO enzyme activity of Qidali,857 and 867 are higher and significantly different from other materials(P < 0.05);The total phenol content of 853,857,867 and Qidali was higher and peaked at 20 days after inoculation,and other susceptible materials appeared later.853,The flavonoid content of Qidali peaked at 20 days after inoculation,and the flavonoid content of 857 and 867 peaked at 30 days after inoculation.Compared with other materials,the total phenol content and flavonoid content of 857 are significantly different(P < 0.05).(3)Research on the detection of disease resistance genes and gene expression in different periods can be concluded,853,857,and 867 containing homozygous Ty-1 and Ty-3 genes are more resistant to TYLCV,and the expression level of anti-TYLCV genes is higher than other susceptible materials as a whole.As long as the inoculation materials containing resistance genes(Ty-1,Ty-2,Ty-3)all show different degrees of resistance.The expression of Ty-1 gene of 867 is significantly different from other materials(P < 0.05),the expression of Ty-2 gene of 853 is significantly different from other materials(P< 0.05),857 and 867 The expression of Ty-3 gene was significantly different from other materials(P < 0.05).(4)Comprehensive judgment and joint analysis of the above three research contents found,853,857,and 867 show immunity,which can be used as good materials to resist tomato yellow leaf curl virus disease,and 817 and 842 show high resistance,which can be used alternative materials. |
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