| The filamentous f-ungus Magnaporthe oiyzae is one of the most devastating plant pathogens,causing blast disease in rice,which severely threatens to world food safety.Currently,the management of rice blast relies on breeding and planting of resistant cultivars,supplemented by chemical pesticides.However,due to easy variation of the pathogen races,the resistant cultivars often lose their resistance after a new pathogenic or anti-fungicide population formation.Therefore,the prevention and control of the rice blast disease is still a durable problem.Important prerequisite for control of the disease is to understand the fungi pathogenicity related molecular mechanisms.Recently,the disease has become an advanced model pathosystem for understanding the molecular basis of plant-fungal interactions because of the availability of the genome sequences of both rice and the fungal pathogen.The interactions are similar to "arms race",including compatible and incompatible interaction.In the process of the incompatible interactions,secretion effectors of M.oryzae,referred to as avirulence(Avr)proteins,will be recognized by the cognate R genes,triggering the defense response and associating with a hypersensitive response(HR)at the infection site that inhibits pathogen proliferation.However,pathogens deliver new effector proteins to escape from the host recognition or suppress the defense response.The effectors facilitate infecting by rice blast as toxic factors.So the research of effectors provid a better understanding of the molecular underpinnings of the rice-M.oiyzae interaction.In this paper,we detailedly investigated the function of the effector Iug 12 during its pathogenic processes,and the main results are showed as follows:Here,we cloned an effector IUG12 in Y34 strain.Then we knocked out it and researched its biological function.Compared with the wild type,the ?iug12 showed attenuated virulence on the susceptible rice cultivar LTH.IUG12 disruption resulted in slower formating of conidium appressorium.However,the generation of appressorium turgor pressure was not altered.Rice leaf sheath as well as barley epidermis penetration assay showed that the appressorium of both the wild type and mutants can invade in the host cell,but the infectious hyphae of the mutant displayed restricted growth in primary infected rice cell.Diamino benzidine staining also revealed an accumulation of ROS around rice cells with ?iug12 hyphae,indicating defense response was strongly activated in plants infected by the mutant.In addition,The defense related genes in salicylic acid signaling pathway were significantly upregulated in the mutant infected rice plants,showing that Iug12 effected SA defense response.Effectors of M.oryzae can enter host cell to destroy or interference the immunity response during M.oryzae infect rice,promoting infection.So to identify the effectors target protein is significant for revealing its virulence mechanism.In order to elucidate the lug 12 virulence mechanism,the yeast two-hybrid was used to screen the potential host targets of Iug12 in rice cDNA library.With the Iug12 without the signal peptide sequence as the bait,a total of fifty distinct putative interactors were isolated from the rice cDNA library.We used primers of vector pGADT7 and acquired ten potential interacting proteins finally.Among these proteins,Os10g33270 was appeared most times,encoding cyanate hydratase and repeating thirteen times.So it is most likely to be the target protein of Iug12.The interaction between Iug12 and Os10g33270 was confirmed by Yeast Two Hybrid.Taken together,our studies identified lug 12 as a secreted effector,which involved in the pathogenic processes of M.oryzae.The functional analyses of effectors will provide molecular pathological mechanism of the fungi and lead to the prospects for sustainable control of rice blast. |
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