Prevalence and Importance of the Necrotrophic Effector Gene ToxA in Bipolaris sorokiniana Populations Collected from Spring Wheat and Barley

Abstract

Bipolaris sorokiniana is a nectrophic fungal pathogen that causes foliar and root diseases on wheat and barley. Theose diseases are common in all wheat- and barley-growing regions with more severe outbreaks occurring in under warm and humid conditions. areas. The fungus B. sorokiniana can also infect a wide range of grass species in Poaceae and secrete ToxA, an important necrotrophic effector also identified other wheat leaf spotting pathogens. ToxA is an important effector gene that has been identified in several wheat fungal pathogens including B. sorokiniana. In this study, we investigated the prevalence and virulence role of ToxA were investigated in a collection of 278 B. sorokiniana populations isolates that were mainly collected from spring wheat and barley in the Upper Midwest of the United States or other places, including . A total of 278 B. sorokiniana isolates were evaluated including 169 from wheat leaves, 75 from wheat roots, 30 from barley leaves and four from wild quack grass leaves. ToxA was detected present in the isolates from wheat leaves, wheat roots and wild grass leaves, but was absent notfrom isolates collected in those from barley leaves. Prevalence of ToxA in wheat leaf isolates (34.3%) was much higher than that in wheat root isolates (16%). Sequencing analysis revealed the presence of two haplotypes with the majority being BsH2. All ToxA+ isolates produced the functional effector in liquid cultures. Pathogenicity assays revealed that ToxA+ isolates caused significantly more disease on spring wheat lines harboring Tsn1 than their tsn1 mutants, suggesting the ToxA-Tsn1 interaction plays an important role in spot blotch development. This work confirms the presence and importance of ToxA in B. sorokiniana populations from infecting wheat and thus, the need to eliminate breeding of Tsn1 out from spring wheat cultivars can to reduce susceptibility to spot blotch.

Unraveling the dynamics of wheat leaf blight complex: isolation, characterization, and insights into pathogen population under Indian conditions

“…A total of 25 million hectares around the world are affected by the disease ( Sharma et al, 2007 ), about 40 percent of which is in the Indian subcontinent ( Joshi et al, 2007 ). It is also prevalent in wheat-growing regions of Latin America ( Poloni et al, 2009 ; Mann et al, 2014 ; Wu et al, 2021 ), Australia ( Phan et al, 2019 ), West Asia ( Arabi et al, 2019 ; Gholamaliyan et al, 2021 ), North Africa ( Qostal et al, 2019 ; Karamian et al, 2022 ), sub-Saharan Africa ( Tembo et al, 2017 ), Central Asia ( Bozoğlu et al, 2022 ), and the great plains of the United States and Canada ( Friesen et al, 2018 ; Manan et al, 2023 ).…”

Plant–Fungi Interactions: Where It Goes?

“…Plants are always prone to interact with various microbes in different ways which include phytopathogenic and symbiotic associations. In phytopathogenic associations fungi interact with different lifestyles, namely necrotrophic (e.g., Alternaria alternata, A. solani, A. brassicae, Aspergillus flavus, Bipolaris sorokiniana, Botrytis cinerea, Claviceps gigantean, Colletotrichum beeveri, C. gloeosporioides, C. graminicola, C. musae, Sclerotinia sclerotiorum, Stenocarpella maydis, Zymoseptoria tritici) [4][5][6][7][8][9][10][11][12][13][14][15][16]; biotrophic (e.g., Blumeria graminis, Cladosporium fulvum, Hemileia vastatrix, Melampsora lini, Phakopsora pachyrhizi, Puccinia arachidis, Puccinia graminis, Puccinia kuehnii, Puccinia striiformis, Sporisorium scitamineum, Ustilago maydis) [17][18][19][20][21][22][23][24][25][26][27][28]; and hemibiotrophic (e.g., Colletotrichum higginsianum, C. trifolii, Fusarium equiseti, F. oxysporum, F. sacchari, Ganoderma boninense, Magnaporthe oryzae, Phomopsis longicolla) [29][30][31][32][33][34][35][36]. A plethora of fungi also live as symbiotic, e.g., Funneliformis mosseae, Glomus albidum, G. etunicatum, G. mosseae, G. fasciculatum, Glomus albidum, G. etunicatum, G. mosseae, G. fasciculatum, Glomus mosseae, Trichoderma virens [37][38][39][40][41]…”

Sanctuary: AStarshiptransposon facilitating the movement of the virulence factor ToxA in fungal wheat pathogens

“…ToxA is found in the fungal wheat pathogens Pyrenophora tritici-repentis (14), Parastagonospora nodorum (15), and Bipolaris sorokiniana (16), all of which cause severe crop losses in wheat crops globally (17, 18). These pathogens can all infect wheat without ToxA, however presence of this effector has been correlated with more severe disease symptoms indicating this gene can confer a strong fitness advantage (19). Long-read sequencing was used to demonstrate that ToxA is carried within a conserved transposon that was horizontally transferred between P. nodorum and P. tritici-repentis , and B. sorokiniana (20).…”