scholarly journals Septoria Leaf Blotch and Reduced Nitrogen Availability Alter WRKY Transcription Factor Expression in a Codependent Manner

2020 ◽  
Vol 21 (11) ◽  
pp. 4165
Author(s):  
Alistair A. Poll ◽  
Jack Lee ◽  
Roy A. Sanderson ◽  
Ed Byrne ◽  
John A. Gatehouse ◽  
...  

A major cause of yield loss in wheat worldwide is the fungal pathogen Zymoseptoria tritici, a hemibiotrophic fungus which causes Septoria leaf blotch, the most destructive wheat disease in Europe. Resistance in commercial wheat varieties is poor, however, a link between reduced nitrogen availability and increased Septoria tolerance has been observed. We have shown that Septoria load is not affected by nitrogen, whilst the fungus is in its first, symptomless stage of growth. This suggests that a link between nitrogen and Septoria is only present during the necrotrophic phase of Septoria infection. Quantitative real-time PCR data demonstrated that WRKYs, a superfamily of plant-specific transcription factors, are differentially expressed in response to both reduced nitrogen and Septoria. WRKY39 was downregulated over 30-fold in response to necrotrophic stage Septoria, whilst changes in the expression of WRKY68a during the late biotrophic phase were dependent on the concentration of nitrogen under which wheat is grown. WRKY68a may therefore mediate a link between nitrogen and Septoria. The potential remains to identify key regulators in the link between nitrogen and Septoria, and as such, elucidate molecular markers for wheat breeding, or targets for molecular-based breeding approaches.

2021 ◽  
Vol 104 (4) ◽  
pp. 223-225
Author(s):  
N. A. Krupenko* ◽  
I. N. Odintsova

Septoria leaf blotch caused by Zymoseptoria tritici is one of the most harmful diseases in Belarus. Isolates of the pathogen were obtained from northern, central and southern populations: in 2018–2019, whichvaried significantly among in the structure of colonies. The rate of fungal isolates forming yeast-like colonies decreased from 55.0 % in the North of Belarus to 6.7 % in the South, whereas incidence of filamentous isolates increased from 31.3 % to 80.0 %, respectively. In the northern population, phenotypic diversity was high, while in the southern population it was the lowest (Shannon’s index was 1.53 and 1.14, respectively).


Author(s):  
VALERIA Scala ◽  
Chiara Pietricola ◽  
valentina farina ◽  
marzia beccaccioli ◽  
slaven zjalic ◽  
...  

The Septoria Leaf Blotch Complex (SLBC), caused by the two ascomycetes Zymoseptoria tritici and Parastagonospora nodorum, can reduce global yearly yield of wheat by up to 50%. In the last decade in Italy, SLBC incidence has increased; notably, durum wheat has proven to be more susceptible than common wheat. Field fungicide treatment can efficiently control these pathogens, but it leads to the emergence of resistant strains and adversely affects human and animal health, and the environment. Our previous studies indicated that active compounds produced by Trametes versicolor can restrict the growth of mycotoxigenic fungi and the biosynthesis of their secondary metabolites (e.g. mycotoxins). Specifically, we identified Tramesan: a 23 KDa -heteropolysaccharide secreted by T. versicolor that acts as a pro-antioxidant molecule in animal cells, fungi, and plants. Foliar-spraying of Tramesan (3.3 µM) in SLBC-susceptible varieties of durum significantly diminished symptoms of Stagonospora Nodorum Blotch (SNB) and Septoria Tritici Blotch (STB) by 75% and 65%, respectively. Tests were conducted under controlled conditions as well as in field. We show that Tramesan elicits wheat defence against SNB and STB augmenting the synthesis of defence-related hormones, notably JA and SA, that in turn switch on the expression of markers of defence (PR1, PR4 inter alia). In field experiments, yield of durum wheat plants treated with Tramesan was similar to that of untreated ones. The results suggest the use of Tramesan for protecting durum wheat against SLBC.


Author(s):  
V. A. Radivon ◽  
A. G. Zhukovsky

Septoria leaf and head blotch is the most economically significant disease of grain crops in Belarus, as it is annually observed in crops and is highly harmful. Spring triticale is a perspective crop in our country with a high yield potential and grain quality, which, as known, decreases due to diseases development. There is little information on the varieties disease susceptibility, development peculiarities and species composition of septoria blotch of spring triticale, which determined the relevance of our research subject. The paper presents the results of studies in 2015-2019 on susceptibility of spring triticale varieties Uzor, Doublet, Sadko to septoria leaf and head blotch, peculiarities of the disease development depending on weather conditions were revealed and the species composition of pathogens of septoria leaf blotch was determined. It has been determined that severity of septoria leaf blotch by the end of early – soft dough of grain stage reached 36.6 %. Based on calculation of area under the disease progress curve, no significant differences were found in severity of septoria leaf blotch depending on the variety. Severity of septoria head blotch reached 22.7 % by the end of growing season. Direct dependences of septoria leaf and head blotch development on the amount of precipitation have been established, and a close correlation between the severity of septoria head blotch and septoria leaf blotch has been revealed. The species composition of septoria leaf blotch is represented by the fungi Parastagonospora nodorum, Parastagonospora avenae f. sp. triticae and Zymoseptoria tritici. The dominant species was P. nodorum, its frequency reached 99.2 % depending on the variety and growth stage of spring triticale, the second most common fungus was P. avenae f. sp. triticae - up to 58.6 %. For the first time in our country, in-depth research has been carried out to study septoria leaf and head blotch of spring triticale, the results obtained will serve as the basis for development of a protection system.


Agriculture ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 703
Author(s):  
Igor Kushnirenko ◽  
Ekaterina Shreyder ◽  
Nadezhda Bondarenko ◽  
Ekaterina Shaydayuk ◽  
Nadezhda Kovalenko ◽  
...  

The southern Ural is consistently among the 10 best regions in Russia for agricultural production, including wheat. Breeding in the Chelyabinsk Research Institute of Agriculture aims to develop wheat cultivars genetically protected from the main diseases (leaf and stem rust, septoria leaf blotch and tan spot). The genes for resistance to leaf rust, Lr1, Lr9, Lr10 and Lr26/Sr31, alone or in combination, are widespread in cultivars grown in the southern Ural. In 2012, a new wheat cultivar, Chelyaba 75, was proposed for commercial production in the southern Ural, being highly resistant to leaf rust with the highly effective genes LrSp and SrSp transferred from the cuckoo line with the genetic material Aegilops speltoides. Isolates virulent to cv. Chelyaba 75 were not found in Russian populations of Puccinia triticina. Additionally, for a long period, genes Lr29, Lr 41, Lr42, Lr45, Lr47, Lr50, Lr51, Lr53 and Lr57 were characterized by high efficiency. Virulence frequencies to other Lr genes vary annually, but no races with new virulence have been identified. The resistance of lines with the Sr31 and Sr24 genes indicates that the Puccinia graminis population does not contain genotypes with the potentially damaging race Ug99. Mixed septoria and tan spot infections occurred in the southern Ural, with the latter dominating. Races producing the exotoxin ToxA are widely distributed in Pyrenophora tritici-repentis populations. Two causal agents of septoria leaf blotch (Parastagonospora nodorum and P. avenae f. sp. tritici) occur in the region, with the first dominating. Aggressiveness of P. nodorum isolates to wheat cultivars was higher than that of P. avenae f. sp. tritici. All Parastagonospora isolates showed the presence of the SnTox3 marker. SnToxA and SnTox1 markers were found in P. nodorum isolates, usually separately, but in one isolate, these genes were found together. The analysis of the genetic diversity of wheat cultivars grown in the southern Ural, and the pathogenic complex present, indicate that pathogens continuously evolve under the influence of the host plant.


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