| Melon(Cucumis melo L.)is an annual diploid Cucurbitaceous crop,which is widely planted in various countries in the world and has a cultivation history of more than 2,000 years in my country.The fruit is crispy and rich in nutrients.However,melons are susceptible to various pathogens in the production process.Among them,powdery mildew is the most serious infestation of melons,and melon powdery mildew has a wide variety of physiological races and differentiates quickly.Therefore,the prevention and control of melons powdery mildew is an urgent problem in the melon industry.An important issue,the use of disease-resistant breeding to solve melon powdery mildew is now the most effective and fastest method.This experiment firstly identified the species of the physiological races of melon powdery mildew in Shandong Province,and formulated the F1 and F2 populations with high resistance to powdery mildew melon material ’M1’ and high susceptibility material’B29’,and determined by the resistance to susceptibility ratio of the F2 population.The resistance genetic rule of melon material ’M1’,and the combination of BSA sequencing technology and SSR molecular marker technology were used to screen out markers linked to powdery mildew resistance genes,and molecular markers were used to identify melon powdery mildew resistance.Below are key research findings:1.The powdery mildew pathogens on the severely affected leaves of 6 main melon producing areas in Shandong Province were used to make a spore suspension,and 13 internationally recognized hosts were inoculated with powdery mildew using the spray method.First,the spore morphology was observed with a 10×40 times optical microscope,And then compared the host’s resistance to susceptibility after inoculation,and determined that the physiological races of powdery mildew in 6 main melon producing areas in Shandong Province were race 1 of powdery mildew.Using the high-resistant inbred line ’M1’ and the high-susceptible inbred line ’B29’ as parent materials,the F1 generation and F2 population were used for genetic analysis.F1 showed powdery mildew resistance materials,and the resistance to susceptibility ratio of F2 population was 2:1.The results of the experiment were that the resistance of the highly resistant inbred line ’M1’ was controlled by multiple pairs of dominant genes.2.Use the F2 segregation population to construct an anti-disease pool,and sequence the parental and 4 gene pools of anti-disease and susceptibility respectively,and conduct preliminary positioning of anti-disease genes through the BSA method.The sequencing results showed that the powdery mildew resistance gene was located in the range of 0-0.386 Mb on chromosome 2.SSR molecular marker technology was used to gradually screen polymorphic primers in the parents and F1,and finally 4 pairs of markers were screened out of the parents,F1 and the resistance to susceptibility gene pool to show polymorphism.Further amplification was carried out in the F2 segregating population,and the linkage distance between the marker 2SSR1 on chromosome 2 and the disease resistance gene Pm was 30.3 c M.The mapping result was consistent with the BSA sequencing result,and the mapping interval was narrowed;the resistance on chromosome 4 The disease gene Pm was located between the markers 4SSR4 and4SSR5,and the linkage distance of 4SSR4 was 6 c M;the linkage distance between the disease resistance gene Pm and the marker 6SSR1 on chromosome 6 was 8.3 c M.Using 4 pairs of markers linked to disease resistance genes to test the resistance of 28 melon germplasm materials,it was found that the field resistance survey results were compared with the molecular identification results using 4SSR4 markers,and the coincidence rate of the two results reached more than 85%.It is proved that 4SSR4 can lay the foundation for molecular-assisted selection. |
PDF Full Text Request