Investigation On Sclerospora Graminicola And Analysis Of Microbial Diversity In Diseased Leaves

Sclerospora graminicola is an important disease that affects the yield of Setaria italica.In particular years,the incidence of some varieties is more than 50%.In this study,the pathogenicity and influence of other pathogenic bacteria on Sclerospora graminicola were investigated in some areas of Shanxi Province,and the germination conditions of oospores of Sclerospora graminicola were explored,and the influence of Sclerospora graminicola on the phenotype of Setaria italica plants was analyzed.The main results are as follows:1.Through the investigation of the incidence and disease index of Sclerospora graminicola in some areas and different varieties in Shanxi Province,the highest incidence of super precocious 21 was 57.7%,and the lowest incidence of Jingu 20 was 1.3%.However,the incidence of Jingu 21 in different regions is generally high in 2018,up to 52.2%.In addition,Sclerospora graminicola has a great influence on the phenotype of Setaria italica plants.Generally,the plant height of hedgehog head is shorter than that of healthy plants,the ear length is shorter,the diameter of ear axis is coarser,the length of ear stalk is shorter,and the number of leaves is reduced.2.The germinating conditions of oospores of Sclerospora graminicola were studied.It was found that there were germinating tubes on the wall of oospores treated with coleoptile juice,treated with germinating Jingu 21 seeds and mixed treatment.However,the oospores treated with soil maceration and unicorn endolipid showed no signs of germination.The results showed that the germination metabolites of Setaria italica seed had the most obvious effect on the germination of oospore.3.Nine strains of culturable fungi were isolated and purified from the gray back layer of Setaria italica.They were labeled HB-1 to HB-9.After morphological and molecular identification,HB-1 and HB-5 were identified as Alternaria,HB-2,HB-6 and HB-7 as Fusarium,HB-3 and HB-4 as Rhizoctonia,HB-8 as Gibberella,HB-9 as Penicillium.4.The results of pathogenicity test of epiphytes in "gray back" leaves of Setaria italica showed that the two fungi HB-6 and HB-7 had slight infection on healthy leaves of Setaria italica.The results showed that HB-6 was Fusarium graminearum,HB-7 was Fusarium incornatum.5.Based on the analysis of the microbial diversity of epiphytes in the gray back stage of Sclerospora graminicola and the classification and identification of culturable fungi,there are 12 kinds of Bacteroidetes and Proteobacteria on the gray back of Setaria italica leaves.The culturable fungi are Alternaria,Fusarium incornatum,Rhizomucor,Fusarium graminearum,Gibberella,Penicillium sp.and so on.