| Grape(Vitis)is one of the most agricultural and economically valuable fruit trees in the world.However,during the growth and development of grapes,a variety of pests and diseases have seriously affected the yield and quality of grapes,and affected the development of the grape industry.Grape downy mildew spreads quickly and is severely harmful.At present,a large number of fungicides are used at China and abroad to restrict the grape downy mildew.However,the irrational use of pesticides will not only mutate the strains,thereby giving birth to drug-resistant individuals,but also pollute the environment,and drugs remaining on agricultural products may even harm human health.Therefore,breeding new grape varieties resistant to downy mildew is the fundamental way to solve grape downy mildew.In this experiment,we used 3 grape combinations which were hybrid by Vitis vinifera and Vitis labrusca,and collect their leaves as materials to make leaf discs for inoculate the P.viticola.In addition,we also used a variety of grading methods to identify and classify F1 generations resistance phenotypes and use the integrated genetic map of grapes to detect QTLs which resistance downy mildew.In order to explore the genetic characteristics of grape downy mildew resistance,to find grape downy mildew resistance genes,and to provide theoretical reference for grape downy mildew resistance breeding,and to contribute to molecularly assisted breeding and selection of grape downy mildew resistance.The findings of this experiment are as follows: 1.In this experiment,we used 3 grape combinations ‘Red Globe'(Vitis Vinifera L.)× ‘Venus Seedless'(Vitis Vinifera L.× Vitis labrusca L.),‘Zhuosexiang'(Vitis Vinifera L.× Vitis labrusca L.)× ‘Victoria'(Vitis Vinifera L.)and ‘Zhuosexiang'(Vitis Vinifera L.× Vitis labrusca L.)× ‘Red Globe'(Vitis Vinifera L.)which were hybrid by Vitis vinifera and Vitis labrusca,and collect their leaves as materials to make leaf discs for inoculate the P.viticola at 2018 and 2019.Use the Susceptive index of sporangium areas,Susceptive index of sporangium areas,and Leaf hairs density index to calculate and analyze the test results of each combination.Results showed that in the two-year experiments,the resistance of Vitis Vinifera parents was always stronger than that of Vitis Vinifera L.× Vitis labrusca parents after inoculation.Quantitative traits are inherited in the offspring;a certain proportion of super-parent strains have discovered in each combination.2.After statistics and analysis of the LH(leaf hair)density index of ZV and ZR populations have growing leaf hairs,and we found that in the ZV population,LH density index is negatively correlated with SI of sporangium areas and SI of sporangium density on discs.And the correlation coefficient is-0.208 ~*~*--0.574 ~*~*,which shows that the denser the hair on the back of grape leaves,the stronger the disease resistance.In the ZV combination,14% of the super-parents appeared,and these individuals could be used as resources for downy mildew breeding.3.Using 2018 and 2019 phenotypic datas combined with grape integrated genetic maps to detect QTL locus for downy mildew resistance,a total of 13 QTLs that may be related to grape downy mildew resistance were located in LG 3,5,6,8,9,12,13,14,15;loci 12 is on the same chromosome as LH1 and has a similar physical genetic location;Locus 3 and 4 have higher LOD and Rate values,and may serve as two new RPV on LG 8 to resistance the grape downy mildew.4.In the detecting QTL interval at this experiment,gene VIT?214s0081g00780,VIT?209s0002g06210,VIT?209s0002g06230,and VIT?209s0002g06260 were screened for four possible downy mildew resistance genes.Use q RT-PCR technology to verify the gene relative expression at four parental leaves after inoculation,and the results showed that: four genes have the same expression pattern as disease resistance genes,and the relative expression of Venus Seedless at the same time was significantly higher than that of other varieties.In addition,the gene VIT?209s0002g06260 was cloned at this test,and sequence alignment was found that the identity of the 4 parents with the reference gene sequence was 92.07%-99.78%;the domain was predicted by smart,which proved that it is a CC-NBS-LRR gene. |
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