Leaf Cuticle And Mycoparasite Contributes To Melampsora Larici-populina

Melampsora laricii-populina,as one of the main pathogens of poplar leaf rust,which seriously hinders the development of poplar and the ecological and economic construction of forestry.As an obligate parasitic fungus,M.laricii-populina has strong selectivity to the host and co-evolution with the host.In addition,rust is also facing heavy parasitism of other fungi in natural ecosystems.This study mainly studied three contents to further improve the control of M.laricii-populina,involving the relationship between leaf structure and rust resistance in different poplars,the contribution of cuticle in non-host resistance,the interaction of mycoparasite from M.larici-populina.And the study results are as follows:1?Through the investigation on Uredinial density in 29 poplar clones form Weihe and Qinling,it was showed the resistance to Melampsora larici-populina had significant differences in different poplar sections.Tacamahaca was the susceptible host of M.larici-populina,Aigeiros was the resistant host,Leuce was the non-host;According to the correlation between leaf structure and rust resistance of poplar,it was found that the cuticle thickness and epidermal cell wall thickness of poplar leaves had a stable positive correlation with rust resistance in different poplars,which provided two morphological indicators to rapid screening of rust-resistant poplars in production.2?Poplar cuticle mainly composed of a large number of alcohols,alkanes,fatty acids,esters and a small amount of ketones,phenols,ethers and amides,of which the proportion of alcohols is up to about 30%.Populus tomentosa,a non-host of M.larici-populina,P.deltoides cv.‘I-69',a strongly resistant host,and P.purdomii,a susceptible host,for urediniospore germination in leaf cuticle extracts.The results proved cuticle of non-host had antirust components,which revealed that the leaf cuticle had an important role in non-host resistance.Four anti-rust components of cuticular were successfully identified by using statistics to select putative defense compounds and the verification experiments.The four defense components are: Aucubin,hexakis(trimethylsilyl)ether,Catechol,2TMS derivative,7,9-Di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione,Trifluoroacetamide,2TMS derivative.Further analysis of the structure-activity relationship showed that the four defense components had a high toxicity risk but no genotoxicity(carcinogenicity).Thus,these defense components had the potential to be widely applied in nature.3?A mycoparasite of Melampsora larici-populina.fungi with significant antirust activity was isolated from urediospores that was identified as Cladosporium cladosporioides.The C.cladosporioides can degraded cell wall of urediniospore.A large number of C.cladosporioides mycelium could cause the cell wall to rupture and invade the urediniospore protoplasts,absorbing nutrients,killing the rust.And C.cladosporioides can produce a large number of tiny and penetrating parasitic spores infecting the urediniospore.