Pyrenophora teres: Taxonomy, Morphology, Interaction With Barley, and Mode of Control

Abstract

Net blotch, induced by the ascomycete Pyrenophora teres, has become among the most important disease of barley (Hordeum vulgare L.). Easily recognizable by brown reticulated stripes on the sensitive barley leaves, net blotch reduces the yield by up to 40% and decreases seed quality. The life cycle, the mode of dispersion and the development of the pathogen, allow a quick contamination of the host. Crop residues, seeds, and wild grass species are the inoculum sources to spread the disease. The interaction between the barley plant and the fungus is complex and involves physiological changes with the emergence of symptoms on barley and genetic changes including the modulation of different genes involved in the defense pathways. The genes of net blotch resistance have been identified and their localizations are distributed on seven barley chromosomes. Considering the importance of this disease, several management approaches have been performed to control net blotch. One of them is the use of beneficial bacteria colonizing the rhizosphere, collectively referred to as Plant Growth Promoting Rhizobacteria. Several studies have reported the protective role of these bacteria and their metabolites against potential pathogens. Based on the available data, we expose a comprehensive review of Pyrenophora teres including its morphology, interaction with the host plant and means of control.

Genotypic Variation of Nitrogen Use Efficiency and Amino Acid Metabolism in Barley

“…Signaling, ionic transport, and metal enzymes are common over-represented functional categories in our study and in the aforementioned transcriptomic analyses. The differential expression of genes related to defense in the RNAseq is in agreement with the observed impact of N supply on barley susceptibility to one of the major pathogens affecting barley especially in Morocco (Jebbouj and El Yousfi, 2009;Backes et al, 2021a). It is known that N nutrition can affect plant tolerance to pathogens but positive and negative correlations have been observed depending on the plant-pathogen interaction considered (Fagard et al, 2014;Mur et al, 2017;Sun Y. et al, 2020).…”

“…Significant GO overrepresented functions encoded by genes differentially expressed in the three genotypes were found to be related to stress responses, defense, signaling, and cytoskeleton remodeling (Figure 5). The differential regulation of defense-related genes prompted us to test the impact of N on barley tolerance to Pyrenophora teres Drechsler (anamorph Drechslera teres) one of the major pathogens affecting barley especially in Morocco (Jebbouj and El Yousfi, 2009;Backes et al, 2021a). Disease severity was higher under HN compared to LN in M5 and GP (Supplementary Figure 6).…”

Effectiveness of fungicides with different modes of action against net blotch disease of two-rowed spring barley

“…Although genus Pyrenophora contains several species of fungi that cause foliar disease in barley (Backes et al, 2021), out of these, Pyrenophora teres is the causal agent of net blotch disease. It presents two genetically distinct forms that are the most important foliar pathogens of barley crop, found in all regions of the world suitable for barley cultivation (Clare et al, 2020).…”

Management of Pyrenophora teres f. teres, the Causal Agent of Net Form Net Blotch of Barley, in A Two-Year Field Experiment in Central Italy

“…The integrated management of net blotch is primarily based on the adoption of correct agricultural practices. Crops residues, seeds, and wild grass species are the inoculum sources responsible for spreading the disease [ 15 ]. Primary inoculum destruction, sowing healthy seeds, crop rotation, and soil tillage are the first steps to effectively manage the disease [ 16 ].…”

“…Because of the high genetic variability observed in P. teres , the obtainment of barley lines with complete resistance to all pathogen isolates is very difficult [ 23 ]. However, genes for net blotch resistance or quantitative trait loci (QTL) have been identified and they are distributed on all seven barley chromosomes [ 15 ]. Nevertheless, to date, very few cultivars exhibit resistance to the net form of the disease, while most of them have a lower susceptibility reaction to the spot form [ 21 ].…”