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

Abstract

Virulence factors of the pathogen Stagonospora nodorum Berk. are numerous necrotrophic effectors (NEs) (SnTox), which interact with the products of host susceptibility genes (Snn), causing the development of the disease. In this study, 55 accessions of bread spring and winter wheat were screened for sensitivity to NEs SnToxA, SnTox1, and SnTox3 using different isolates of S. nodorum. In the studied panel of wheat, 47 accessions were modern commercial cultivars grown in Russia and 8 cultivars were historic wheat accessions from the N. I. Vavilov Institute of Plant Genetic Resources in Russia. In general, our wheat panel differed from other wheat collections with available data in that it was less sensitive to SnToxA and SnTox3, and more sensitive to SnTox1. Six sources of strong SNB resistance were identified in our wheat panel. In addition, during the study, wheat cultivars were identified as appropriate objects in which to study the different effects of SnTox-Snn interactions, which is important for marker-assisted selection for SNB resistance. The current study has shown, for the first time, that the expression level of Snn1 and Tsn1 susceptibility genes and the disease severity of the different wheat cultivars are interconnected. Future work should focus on the deep characterization of SnTox-Snn interactions at the molecular level.

The Role of Cytokinins and Abscisic Acid in the Growth, Development and Virulence of the Pathogenic Fungus Stagonospora nodorum (Berk.)

“…It was previously shown that the virulence of S. nodorum strains depends on the level of expression of NE genes [26,27,30,47,48]. Isolates SnB, Sn4VD and Sn9MN-3A studied in this work had different virulence [32,33], and as our results showed, they differed in the pattern of expression of NE genes (Figure 6). Isolates SnB and Sn9MN-3A were characterized by higher expression of the SnToxA and SnTox3 genes compared to the avirulent isolate Sn4VD (Figure 6).…”

“…Previously, we showed that isolates of S. nodorum SnB and Sn9MN-3A contain SnToxA and SnTox3 in their genome sequences of NEs, and these isolates are virulent against wheat genotypes carrying the corresponding susceptibility genes complementary to these effectors [32,33]. The S. nodorum Sn4VD isolate contained in its genome the genes encoding three NEs: SnTox1, SnToxA and SnTox3, but the Sn4VD isolate was avirulent and weakly infected susceptible wheat genotypes [32].…”

Genetic Diversity for Effective Resistance in Wheat Landraces from Ethiopia and Eritrea to Fungal Diseases and Toxic Aluminum Ions

“…Only genes for resistance to Bgt Pm12 , PmSp , and PmKu were described as effective against the pathogen populations from the northwestern part of the Russian Federation [ 29 , 30 , 58 ], but samples with these genes were found to be susceptible in 2022 [ 21 ]. Several varieties of bread wheat were evaluated as resistant to HLB [ 56 , 59 ] and SNB [ 60 , 61 ], but their re-evaluation showed their susceptibility (not published). Only four genes for yellow rust resistance ( Yr5 , Yr10 , Yr15 , and Yr24 ) have been described as effective against Pst in Russia [ 31 ].…”