Reactive Oxygen Species in Host Plant Are Required for an Early Defense Response against Attack of Stagonospora nodorum Berk. Necrotrophic Effectors SnTox

Abstract

Reactive oxygen species (ROS) play a central role in plant immune responses. The most important virulence factors of the Stagonospora nodorum Berk. are multiple fungal necrotrophic effectors (NEs) (SnTox) that affect the redox-status and cause necrosis and/or chlorosis in wheat lines possessing dominant susceptibility genes (Snn). However, the effect of NEs on ROS generation at the early stages of infection has not been studied. We studied the early stage of infection of various wheat genotypes with S nodorum isolates -Sn4VD, SnB, and Sn9MN, carrying a different set of NE genes. Our results indicate that all three NEs of SnToxA, SnTox1, SnTox3 significantly contributed to cause disease, and the virulence of the isolates depended on their differential expression in plants (Triticum aestivum L.). The Tsn1–SnToxA, Snn1–SnTox1and Snn3–SnTox3 interactions played an important role in inhibition ROS production at the initial stage of infection. The Snn3–SnTox3 inhibited ROS production in wheat by affecting NADPH-oxidases, peroxidases, superoxide dismutase and catalase. The Tsn1–SnToxA inhibited ROS production in wheat by affecting peroxidases and catalase. The Snn1–SnTox1 inhibited the production of ROS in wheat by mainly affecting a peroxidase. Collectively, these results show that the inverse gene-for gene interactions between effector of pathogen and product of host sensitivity gene suppress the host’s own PAMP-triggered immunity pathway, resulting in NE-triggered susceptibility (NETS). These results are fundamentally changing our understanding of the development of this economical important wheat disease.

Novel Sources of Resistance to Stagonospora nodorum and Role of Effector-Susceptibility Gene Interactions in Wheat of Russian Breeding

“…Genotyping of the accessions from the wheat panel and studying the expression of susceptibility genes were carried out using intact 7-day-old seedlings. The resistance/susceptibility of genotypes was evaluated on the separated first leaves [24].…”

“…The 7-day-old seedlings were placed in separate vessels and were sprayed with suspensions of S. nodorum isolates SnB, Sn9MN-3A, or Sn1SP with 10 6 spores mL −1 in 0.02% Tween-20. Control plants were sprayed with a solution containing only the wetting agent Tween-20 (0.02%) [24]. The volumes of all solutions allowed full moistening of leaves.…”

Action Mechanisms of Effectors in Plant-Pathogen Interaction

“…SnToxs, including SnToxA, SnTox1, and SnTox3, in the powdery mildew fungus Stagospora nodorum Berk. have similar roles to cause necrosis [ 312 , 313 , 314 ].…”

Triptolide inhibits the Apoptosis and Reactive Oxygen Species Production in Hydrogen Peroxide-Treated Nasal Epithelial Cells by Regulating PTEN/PI3K/AKT Signaling Pathway

“…When this balance is broken by excessive ROS, it is called "oxidative stress". Oxidative stress can lead to diseases, including cancer, neurological diseases, hypertension, ischemia and reperfusion [18][19][20] , diabetes, chronic obstructive pulmonary disease and asthma [21][22][23] . ROS plays an important role in the regulation of important cellular processes such as oxidative stress, apoptosis and gene expression.…”

“…Under normal conditions, oxides and antioxidants maintain a relative balance, which is very necessary to protect the normal function of the airway. When the airway is exposed to environmental factors such as animal hair, dust, mites, fungi, pollen, cigarette smoke, volatile chemicals, occupational dust, automobile exhaust and sulfur dioxide [18,19,23,24] , these irritants stimulate epithelial cells to produce too many harmful oxides, break the balance between oxides and antioxidants, and finally lead to oxidative stress and airway inflammation.…”