Analysis Of Primary Mapping Of Resistance To Aspergillus Flavus Gene And Haploid Induction And Doubling Technique In Maize

The current planting area of corn is largest in China and aflatoxin contamination caused serious security risks to Maize.So the effective control of Aspergillus flavus harm to the corn production,reduce or eliminate aflatoxin contamination in maize are the major problem that needs to be solved urgently in maize production and food security.Cultivating new varieties using the germplasm materials resistant to Aspergillus flavus is the most economical and convenient way to control aflatoxin contamination.This study is mainly carried out in the following aspects.In this article,ecological resources in Anhui spring maize area were identified using optimization field acupuncture inoculation of Aspergillus spores suspension to identify method for maize resistance to Aspergillus flavus(the field of acupuncture inoculation method);the resistant and susceptible parents and their progeny F2:3 families as experimental material,using SSR molecular marker technology,the localization of the genes for resistance to aflatoxin in maize was carry out;to accelerate the breeding process to shorten the breeding cycle,and to cultivate new varieties of maize resistance to Aspergillus flavus as soon as possible,the maize haploid induction and doubling were carried out.The results are as follows:1.126 spring maize inbred lines with resistance to Aspergillus flavus were identified using the optimization method of field acupuncture inoculation of Aspergillus flavus spore suspensions in 2014(field acupuncture inoculation identification method).According to the association analysis of the field inoculation incidence of 126 inbred lines,combining with the results of laboratory determination of the aflatoxin B1 content,differences among 30 inbred lines were significant.In2015,the repeated field inoculation experiment was carried out in the 30 inbred lines.Identification data of two years were analyzed by Paired T-test,and the results of resistance identification performance in 2 years had no significant difference,which were consistent,suggesting that the Maize identified by field acupuncture inoculation identification method had stable resistance to Aspergillus flavus,were reproducible and less affected by environment,which can be as a corn of Aspergillus flavus resistance identification method.By correlation analysis of field inoculation incidence and determination of aflatoxin B1 content,the relationship between Aspergillus flavus infecting corn and toxin production had an extremely significant positive correlation,In 2014,the field infection results showed that the correlation coefficient between the content of aflatoxin B1 and the level of the disease was 0.892.In 2015,the field infection results showed that the correlation coefficient between the content of aflatoxin B1 and the level of the disease was 0.805,suggesting that the level of aflatoxin B1 content could be determined through the field infection.2.Genetic mapping population preliminary constructed by hybridization of highly disease resistant materials H152 and highly susceptible materials PI143.101 pairs of SSR primers were used for polymorphism screening according to resistant and susceptible materials covering all the 10 chromosomes of maize Bin area,and 15 pairs polymorphic SSR primers were selected.According to the disease level survey results of F2: 3 lines,15 high susceptible and 15 high resistant plants were selected to construct resistant and susceptible pool respectively for the PCR specific amplification after equivalent DNA mixture.Three pairs of primers showed a polymorphism in the resistant and susceptible pool respectively,which were umc1992 on second chromosome,umc2259 and umc2174 on third chromosome.The function relationship between the recombination rate(R)and the genetic distance(M)of the two loci on the chromosome was used in the Kosambi function,and genetic distance was(M)=ln[(1+2r)/(1-2r)]*1/4.The genetic distances of 3 SSR molecular markers were calculated by exchange values of F2: 3 family group.And the distance between resistance genes and close genetic marker umc2259 was 0.66 c M and the distance between resistance genes and umc2174 was 0.75 c M,while the distance between disease gene and genetic marker umc1992 was 0.80 c M.3.Three induced lines,Stock6 improvement department,high inducing No.1and MT041 with some blood and trait differences were constituted into three induced line hybrid combinations.The plant growth,resistance and the amount of loose powder of hybridized combination had the superior advantages to parent.The inducibility of combined hybrid by stock 6 improved lines×high induced 1 was strongest,further validating that the hybrid combinations had stable ability for haploid induction.Through doubling treatment by different concentration of pronamide,When the concentration of the pronamide solution was 40 ppm,the doubling rate was the highest,reaching 9.88%.