Infection, Colonization And Detection Of Chaetomium Globosum ND35 Strain On Plant And Its Effect On Plant Growth

Chaetomium globosum ND35 strain is a kind of endophytic fungus isolated from Populus tomentosa. ND35 shows its antagonism against many plant pathogens, and the Secondary metabolites produced by ND35 will promote the growth of plants and induce resistance to plant diseases. In order to understand the mode of infection and colonization on plant by C. globosum ND35 strain and effect on plant growth after inoculation with C. globosum and investigate fast and accurate detection method for C. globosum ND35 strain as well. Five research sections have been investigated such as observation of infection and colonization on host plant poplar, specific RAPD-DNA markers transfer of C. globosum ND35 strain, effects on different plants by C. globosum ND35 strain, tissue isolation and molecular detection of crops in the field after inoculation with C. globosum ND35 strain and preminary study on detection of C. globosum ND35 strain using real-time PCR. The results have been obtained as follow:The infectious behaving and mode of hyphae from C. globosum ND35 strain on root surface of plant have been investigated through light microscope and fluorescence microscope as well as immunofluorescence labeling technique. Meanwhile, the establishment process has been studied by light microscope and transmission electron microscope (TEM) in this paper. The result shows that hyphae have been able to infect into root from the gap between epidermic cells after inoculation for 24 h with C. globosum ND35 strain. After inoculation for 48 h, hyphae have colonized in intercellular space in the outer cortex. After inoculation for 72 h, many hyphae have colonized in the epidermic cells. Appressorium has been formed in the tips of hyphae at the penetration point. Normally, most hyphae have colonized in the epidermic cells of host plant poplar root, a small number of hyphae in outer cortex cells. This may provide foundation for in-depth investigating the interactions between the biocontrol fungi, plant pathogen and host.This paper reports the detection of C. globosum strain with SCAR molecular marker for the first time. 14 strains of Chaetomium and 6 strains of plant pathogens have been analyzed with random primer based on optimal RAPD system and screened specific RADP fragment of ND35. A pair of primers has been designed based on gene sequencing result: Cg ND35-F:5'-GTTGCCAGCCCGAGGGGAAG-3',Cg ND35-R:5'-GTTACCAGCCATGCCTTGA AG-3'. The meaningful SCAR marker has been first got from this study. Positive results have been got through recovery test on specificity and sensitivity. This method is fast, sensitive, and precise. The accuracy of SCAR marker has been guaranteed by both selected DNA fragment of ND35 and pair of primer designed including random primer sequence in this study. Thus fast and accurate detection of C. globosum ND35 strain with molecular marker has been realized and provided foundation for detection of ND35 strain in the field.The conventional PCR and the newly designed set of primer have been applied to investigate the establishment of ND35 strain in the field plants, and provided a fast, precise, and simple method to test the endophytic fungi in this study. Optimized CTAB method which is effective, efficient, and low cost has been applied in this study, thus optional genomic DNA has been got and solid foundation has been made for further investigation. C. globosum ND35 strain has been successfully detected in poplar, ginger, wheat, and potato by using the primers specific for ND35 strain designed by preliminary SCAR marker. For the four supplied plants, alteration in plant growth and isolation result from plant tissues inoculated and non-inoculated with C. globosum ND35 strain have been investigated in this study. Result indicated that ND35 stain can establish in all the plant tissues that tested with a slightly difference in the amount of establishment in different tissues; the plant in experimental group has a bigger growth amount comparing with the plant in control group; this shows that C. globosum ND35 strain have promoted the growth of plant.A set of specific primers for real-time PCR has been designed by using SCAR marker in this study. Besides, the optional real-time PCR system and amplification program have been investigated by using the newly designed primers and C. globosum ND35 strain genomic DNA served as template. Positive results have been got from this study, thus lay a good foundation for the application of real-time PCR in the dynamic of endophytic fungi in plants.