Study On Population Analysis Of Fusarium Spp. And Relationship With Fusarium Graminearum Infection On Different Hosts In The Maize/Soybean Intercropping

Maize and soybean intercropping is a typical intercropping pattern between legume and cereal crops.However,whether there is mutual infection among Fusarium species under maize/soybean intercropping and resulting in annual cycle infection of pathogens is still not clear.Therefore,the study on the species of Fusarium spp.in soybean and maize,and the pathogenicity of Fusarium spp.on different parts o f soybean under maize/soybean intercropping could provide theoretical and practical guidance for the prevention and treatment of maize stem rot and soybean root rot.In our current study,the morphological characteristics and molecular identification of pa thogenic fungi were firstly used to identify Fusarium species of maize stem rot and soybean root rot in the maize/soybean intercropping pattern in Sichuan,China;and meanwhile,the pathogenicity of Fusarium species isolated from different soybean tissues was detected to explore their cross-infection relationship on soybean root,stem and pod;As two hosts of F.graminearum,the infection relationship of F.graminearum on soybean and maize,and defense mechanism of soybean induced by F.graminearum were determined through the detection of a range of defense responses after inoculation with F.graminearum caused maize stalk rot.The main research results were seen as follows:Samples of maize stalk rot were collected for isolation and purification from four locations of the maize/soybean intercropping.Fusarium species were identified by morphological characteristics and r DNA-ITS and EF1-α sequence analysis,and the pathogenicity was detected by seedling puncture inoculation.Results were a total of 103 strains of pure cultures,of which 71 strains of Fusarium,including F.proliferatum,F.solani,F.verticillioides,F.graminearum,F.oxysporum,F.fujikuroi and F.equiseti.The pathogenicity test showed that F.graminearum was the most pathogenic,followed by F.proliferatum and F.verticillioides,F.oxysporum and F.equiseti were the least pathogenic,and F.fujikuroi and F.solani were the least pathogenicIntercropping soybean stem rot,root rot and pod rot samples were collected for isolation and purification.Fusarium species were identified by morphological characteristics and r DN A-ITS and EF1-α sequence analysis,and the pathogenicity was detected by seedling puncture inoculation.Results were a total of 103 strains of pure cultures,of which 94 strains of Fusarium,including F.fujikuroi 、 F.equiseti 、F.chlamydosporum 、F.verticillioides、F.oxysporum 、F.graminearum 、F.solani、F.proliferatum and F.commune,among which F.solani and F.equiseti are the most abundant.Moreover,there were differences in the species and separation frequency of Fusarium from different parts of soybean.The main pathogenic Fusarium of soybean stem rot was F.oxysporum and F.proliferatum,among which Fusarium oxysporum was the most pathogenic.The main pathogenic Fusarium of soybean pod rot was F.equiseti,F.proliferatum and F.solani.There are many species of Fusarium spores causing soybean root rot,mainly were F.solani,F.equiseti and F.oxysporum.According to the detection of soybean root rot pathogenicity,F.oxysporum was the most serious,followed by F.equiseti and F.graminearum.The pathogenicity of soybean was tested by mutual inoculation of different parts of soybean,results showed that Fusarium spp.isolated from stem rot,root rot and pod rot of soybean could cause alternation infection.The pathogenicity test of soybean stem showed that 6 kinds of Fusarium spp.isolated from pod rot and 8 kinds of Fusarium spp.isolated from soybean root rot all could cause soybean stem rot,among which the most serious ones was F.oxysporum,followed by F.equiseti and F.graminearum.The pathogenicity test of soybean seed showed that 3 kinds of Fusarium spp.isolated from stem rot and 8 kinds of Fusarium spp.isolated from soybean root rot all could cause high incidence of soybean seeds,and mycelium covering the seed surface hinders seed germination.The patho genicity test of soybean root showed that 6 kinds of Fusarium spp.isolated from pod rot and 3 kinds of Fusarium spp.isolated from soybean stem rot all could cause soybean root rot,among which the most serious ones was F.oxysporum,followed by F.equiseti and F.graminearum.It was proved that stem rot,root rot and pod rot of soybean were interactively infected with each other,and the degree of infection was serious.The stem rot and pod rot of soybean should also be systematically controlled during the disease control of soybean root rot.As the same pathogen of soybean root rot and stem rot,F.graminearum may cause mutual infection under maize and soybean intercropping.Infection of soybean with F.graminearum of maize stem rot can cause soybean disease,and induce a series of disease-resistant mechanisms to resist pathogen infection,such as accumulation of reactive oxygen species,cell anaphylactic necrosis,and accumulation of isoflavone content and expression of disease-resistant genes.Therefore,it can be proved that F.graminearum can infect two crops at the same time and cause diseases in maize and soybean intercropping system,which can provide reference for the related research on the disease prevention and control of soybean root rot and maize stem rot.