Screening Of Tobacco Varieties With Double Resistance To TMV And PVY And Their Physiological Response To Virus Stress

Tobacco is one of the most important economic crops in China.Tobacco mosaic virus(TMV)and potato virus Y(PVY)do great harm to tobacco plants and seriously affect tobacco production and quality.In order to screen TMV and PVY resistant tobacco varieties,20 tobacco varieties were used as test materials to carry out the identification test of artificial inoculation resistance of two kinds of viruses;13 tobacco varieties with different resistance were selected for 28 days after inoculation The correlation between the change rate of each relative physiological and biochemical index and the disease index was analyzed by grey correlation analysis,and 28 days after inoculation by principal component analysis Finally,five tobacco varieties with extreme resistance were selected as test materials to study the changes of physiological and biochemical indexes such as agronomic characters,dry matter accumulation and protective enzyme activity after inoculation.Lay the foundation for the later research of resistance gene mining and molecular mechanism.The main results are as follows:1)The results of artificial identification based on disease index and resistance index showed that the 20 tobacco varieties with double resistance(Immune TMV,high resistance PVY)were Zhongyan 300,TN90 and SY04-3,and the two susceptible varieties were NC89 and NC95.Among them,two double susceptible varieties had earlier onset,the phenomenon of leaves and flowers was very serious and even deformed after inoculation of TMV,the leaf surface was wrinkled,the veins of tobacco leaves were red,black and even necrotic after inoculation of PVY,the leaves were chlorotic and the plants were dwarfed seriously;three double resistant varieties were all disease-free after inoculation of TMV,and the symptoms were light after inoculation of PVY.2)According to the grey correlation analysis,the order of the change rate of relative physiological index and the degree of correlation between disease index was from big to small,which was the change rate of relative MDA activity,the change rate of relative dry matter accumulation,the change rate of relative proline content,the change rate of relative chlorophyll content,the change rate of relative SOD activity,the change rate of relative net photosynthetic rate and the change rate of relative POD activity.Based on the results of principal component analysis of physiological and biochemical indexes at 28 days after inoculation,13 tobacco varieties were classified into SY04-3,TN90,Zhongyan 300,Jiyan 9,Yanshai 10,Yanshai 6,Jianping orchid,Xiaomaxi,Yanshai 7,Yanshai 8,Damaxi,NC89 and NC95.The results are basically consistent with the results of artificial identification.3)According to the changes of leaf area,plant height and dry matter accumulation of five extremely resistant tobacco varieties,with the extension of inoculation time,the control treatment and inoculation treatment increased,but the control treatment was higher than the inoculation treatment,and the decline of double resistant varieties(Zhongyan 300,TN90 and SY04-3)was significantly lower than that of double susceptible varieties(NC89 and NC95).From the changes of chlorophyll content and net photosynthetic rate,the control treatment showed a gradual upward trend,while the inoculation treatment showed a gradual downward trend.After 7-35 days of inoculation,the control treatment was higher than the inoculation treatment,and the decreasing range of double resistant varieties was smaller than that of double susceptible varieties.The activities of protective enzymes(POD,CAT,SOD)in the control treatment kept a stable growth trend,while those in the inoculation treatment increased first and then decreased.When the control treatment was lower than the inoculation treatment,the growth rate of the double resistant varieties was significantly higher than that of the double susceptible varieties;and 35 days after inoculation,the growth rate of the control treatment was higher than that of the inoculation treatment,and the decline rate of the double resistant varieties was smaller than that of the double susceptible varieties.In terms of relative conductivity,MDA content and proline content,the control treatment increase slightly,while the inoculation treatment showed an obvious upward trend.After 7-35 days of inoculation,the increase of relative conductivity gradually increased,during which the increase of double resistant varieties was less than that of double susceptible varieties;when 7 days of inoculation,the increase of MDA content was the largest and then decreased gradually,and the increase of double susceptible varieties was always greater than that of double resistant varieties;after 7-35 days of inoculation,the increase of MDA content was always greater than that of double resistant varieties The proline content of control was lower than that of inoculation,and the increase of proline content increased gradually.The increase of double resistant varieties was significantly higher than that of double susceptible varieties.