Genetic Diversity Of Ustilago Maydis And The Resistance Of Corn Varieties To Corn Smut

Corn plays an important role in Chinese agricultural production and national economy.It is a vital food crop in China and widely cultivated in Northeast China.In recent years,beasuse climatic conditions are changed and the new varieties of corn are popularized,the occurrence of corn smut is increasing frequently,and the yield and quality of corn are greatly threatened.Ustilago maydis is the main reason of corn smut.This paper used modern molecular biology techniques to identify the mating types of Ustilago maydis,and the genetic diversity of Ustilago maydis,and analyzed corn’s resistance to corn smut.The results are as follows:1.Identification of the mating types of Ustilago maydis.There were isolated 82 corn smut strains collected from 11 provinces,mating type identification’s results showed that there are three main types of Ustilago maydis,mfa1,mfa2 and mfa1,mfa2.In the 82 isolates,the mating type of 32 strains are mfa1,accounting for 39.02% of the identified strains;21 strains are mfa2,accounting for 25.61% of the identified strains;29 of the mating types are mfa1 and mfa2,accounting for 35.37% of the total.2.Study on the biological characteristics of Ustilago maydis.The suitable temperature range for germination of teliospores of Ustilago maydis was 20 °C ~ 30 °C,the highest germination rate of teliospores at 25 °C;the influence of different C and N sources suggestesd that monosaccharides,disaccharides and organic nitrogen promote their germination,while the effect of polysaccharide and inorganic nitrogen was not obvious.The p H condition suitable for germination of teliospores was 3.0-8.0.When p H=8.0,the germination of teliospores was the best.3.The genetic diversity of Ustilago maydis.Genetic diversity analysis of 82 strains of Ustilago maydis was carried out by using ISSR molecular marker technology.The results showed that 61 primers were amplified and 55 specific bands were amplified by 8 primers.The proportion of loci was 90.2%;the tested strains are all separated when the genetic similarity coefficient is 0.90,indicating that the genetic diversity of each of Ustilago maydis could be revealed at the DNA molecular level by ISSR molecular marker technology.The results of cluster analysis demonstrated that there was not obviously correlation between the division of ISSR group and the origin of Ustilago maydis,Ustilago maydis from the same area couldn’t be completely divided into the same group,indicating a certain genetic difference among the Ustilago maydis in the same sampling area.4.Corn varieties resistance to corn smut in Liaoning province.The identification of corn varieties resistance to corn smut by the injection method in the 2018.The results found that,the ratio of highly resistant,resisitant,susceptible,highly susceptible was 7%,23%,50%,20%.The data detemined that the performance were not highly.There were only 7 varieties with highly resistant to corn smut,and 50% of the varieties were moderately resisitant.One-quarter of the varieties were susceptible to corn smut.