Septoria yaprak leke hastalığı etmeni Zymoseptoria tritici (Desm. Quaedvlieg & Crous)’ye ait izolatların farklı sıcaklıklardaki fizyolojik ve biyokimyasal özelliklerin belirlenmesi

Abstract-The fungus Zymoseptoria tritici is the causal agent of Septoria Tritici Blotch (STB) disease of wheat leaves. Z. tritici secretes many functionally uncharacterised effector proteins during infection. Here we characterised a secreted ribonuclease (Zt6) with an unusual biphasic expression pattern.-Transient expression systems were used to characterise Zt6, and mutants thereof, in both host and non-host plants. Cell-free protein expression systems monitored impact of Zt6 protein on functional ribosomes, and in vitro assays of cells treated with recombinant Zt6 determined toxicity against bacteria, yeasts and filamentous fungi.-We demonstrated that Zt6 is a functional ribonuclease and that phytotoxicity is dependent on both the presence of a 22-amino acid N-terminal “loop” region and its catalytic activity. Zt6 selectively cleaves both plant and animal rRNA species, and is toxic to wheat, tobacco, bacterial and yeast cells but not to Z. tritici itself.-Zt6 is the first Z. tritici effector demonstrated to have a likely dual functionality. The expression pattern of Zt6 and potent toxicity towards microorganisms suggests that whilst it may contribute to the execution of wheat cell death, it is also likely to have an important secondary function in antimicrobial competition and niche protection.

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Prevalence of QoI resistance and mtDNA diversity in the Irish Zymoseptoria tritici population

Irish Journal of Agricultural and Food Research ◽

10.2478/ijafr-2019-0004 ◽

2019 ◽

Vol 58 (1) ◽

pp. 27-33

Author(s):

S. Kildea ◽

D.E. Bucar ◽

F. Hutton ◽

S. de la Rosa ◽

T.E. Welch ◽

...

Keyword(s):

Septoria Tritici Blotch ◽

Septoria Tritici ◽

Entire Group ◽

Zymoseptoria Tritici ◽

Qoi Fungicides ◽

Quinone Outside Inhibitor ◽

Strain Collection ◽

Increased Sensitivity ◽

Mtdna Diversity

Abstract The emergence and spread of Quinone outside Inhibitor (QoI) fungicide resistance in the Irish Zymoseptoria tritici population in the early 2000s had immediate impacts on the efficacy of the entire group of fungicides for the control of septoria tritici blotch. As a result, a dramatic reduction in the quantities applied to winter wheat occurred in the following seasons. Even in the absence of these fungicides, the frequency of the resistance allele, G143A in the pathogens mtDNA has remained exceptionally high (>97%), and as such, it can be anticipated that continued poor efficacy of current QoI fungicides will be observed. Amongst the isolates with G143A, differences in sensitivity to the QoI pyraclostrobin were observed in vitro. The addition of the alternative oxidase (AOX) inhibitor salicylhydroxamic acid increased sensitivity in these isolates, suggesting some continued impairment of respiration by the QoI fungicides, albeit weak. Interestingly, amongst those tested, the strains from a site with a high frequency of inserts in the MFS1 transporter gene known to enhance QoI efflux did not exhibit this increase in sensitivity. A total of 19 mtDNA haplotypes were detected amongst the 2017 strain collection. Phylogenetic analysis confirmed the suggestion of a common ancestry of all the haplotypes, even though three of the haplotypes contained at least one sensitive strain.

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