| Trichoderma,one of the most important biocontrol fungi,including Trichoderma harzianum,Trichoderma viride,Trichoderma corningii and Trichoderma longibrachiatum.It is widely distributed in soil,water,decayed wood and plant debris,what is easy to grow in wet environment.Trichoderma has good biocontrol effect on many plant pathogenic fungi and bacteria,it can induce plant disease resistance.Gourd is an important ornamental plant,in Northwest Shandong its cultivation and processing was developed into an important characteristic industry.Gourd anthracnose is one of the most important disease which restricts the production efficiency of gourd.It can occur during the whole growth period,especially in fruit,it is seriously affects the ornamental value and commodity of gourd.The environmental pollution is cause by long-term use of chemical pesticides,at the same time,the resistance of pathogens is gradually increasing,what is making the disease more difficult to control.Trichoderma longibrachiatum SMF2 was selected as the research strain to study the biological control of anthrax.The indoor bacteriostatic effect of Trichoderma longibrachiatum SMF2 on gourd anthracnose and the control effect of potted gourd anthracnose were tested.The biological control mechanism of Trichoderma longibrachiatum SMF2 was preliminarily explored through molecular biology,which laid a foundation for improving Trichoderma strain by molecular biology and improving the control efficiency of Trichoderma.Through a lot of experiments,the following results are obtained:(1)Firstly,the pathogen of gourd anthracnose was isolated by routine tissue isolation method,and identified by morphological analysis and molecular biological methods.The results showed that the pathogen belonged to Colletotrichum Lagenarium.Indoor bacteriostasis test and potted gourd anthracnose control test were carried out with Trichoderma longibrachiatum SMF2 strain.The results showed that the inhibition effect of Trichoderma longibrachiatum SMF2 on the pathogen was 83.95%.The spore suspension of Trichoderma longibrachiatum SMF2 was sprayed on the surface of gourd leaves and irrigated on the root,respectively.The severity of the disease was significantly reduced.The results showed that the mechanism of prevention and treatment of the disease may include two aspects: bacteriostasis and inducing disease resistance.(2)In order to better understand the biocontrol mechanism of Trichoderma longibrachiatum SMF2,we studied the biocontrol mechanism of the strain through molecular biology.The optimum conditions for protoplast preparation of Trichoderma longibrachiatum were found through experiments.Hundreds of transformants were obtained by restriction endonuclease-mediated transformation(REMI),and a mutant with significantly reduced conidial production was screened out.At present,further analysis of the mutant is under way.Bioinformatics analysis revealed that there was a transcriptional regulator T245 near TPX1,a polypeptide synthesis gene in a NRPS gene cluster,which had a zinc finger structure.It was speculated that it might be related to the synthesis of short peptides.The full DNA length of the gene was cloned by PCR.Based on the principle of homologous recombination and using plasmid pUCATPH as vector,knockout mutation vector of gene T245 was constructed.The protoplasts of Trichoderma longibrachiatum SMF2 were transformed by REMI.Screening of gene deletion mutants is still in progress.(3)It is speculated that Trichoderma may secrete some effector factors to play a role in this process.Firstly,the secretory proteins of Trichoderma longibrachiatum SMF2 strain were analyzed by bioinformatics.More than 670 secretory proteins were found.Trichoderma longibrachiatum SMF2 was co-cultured with Arabidopsis thaliana.RNA was extracted before and after contact and transcriptome analysis was carried out.414 secretory proteins were found to be expressed in the interaction process,of which 21 secretory proteins were expressed in long-branch trees.The results laid a foundation for further searching for the effective factors in the interaction between Trichoderma longibrachiatum SMF2 and plants. |
