The soil microbiome reduces Striga infection of sorghum by modulation of host-derived signaling molecules and root development

Abstract

Sorghum bicoloris one of the most important cereals in the world and a staple crop for smallholder famers in sub Saharan Africa. However approximately 20% of sorghum yield is annually lost on the African continent due to infestation with the root parasitic weedStriga hermonthica. Existing Striga management strategies often show an inconsistent to low efficacy. Hence, novel and integrated approaches are needed as an alternative strategy. Here, we demonstrate that the soil microbiome suppresses Striga infection in sorghum. We associate this suppression with microbiome-mediated induction of root endodermal suberization and aerenchyma formation, and depletion of haustorium inducing factors (HIFs), root exudate compounds that are critical for the initial stages of Striga infection. We further identify microbial taxa associated with reduced Striga infection with concomitant changes in root cellular anatomy and differentiation as well as HIF degradation. Our study describes novel microbiome-mediated mechanisms of Striga suppression, encompassing repression of haustorium formation and induction of physical barriers in the host root tissue. These findings open new avenues to broaden the effectiveness of Striga management practices.

Inhibition of broomrape germination by 2,4-diacetylphloroglucinol produced by environmentalPseudomonas

“…Indeed, several studies claimed that the suppressiveness of Orobanche sp. as well as Striga hermonthica is associated with the presence of specific bacterial taxa, including Pseudomonas [11, 56]. Since, PGC-producing Pseudomonas can be followed in soil via qPCR approaches [57], determining the correlation between the community of PGC-producing Pseudomonas and the level of parasitic plant infection would bring new insights on the ecological role of these bacteria in suppressive soils.…”

“…This constitute the main problem to constrain their deleterious impact on crops [8]. The survival of the seeds depends on various abiotic factors (pH, humidity, climate) [9] and biotic factors (host plants, soil and rhizosphere microbiota; [6,[10][11][12]. Different agricultural strategies attempt to regulate broomrape populations in agroecosystems, such as crop rotation, triggering the suicidal-germination of the plant parasitic seeds or the use of resistant host plant varieties or chemical herbicides [5].…”

Inhibition of broomrape germination by 2,4‐diacetylphloroglucinol produced by environmental Pseudomonas

“…Indeed, several studies claimed that the suppressiveness of Orobanche sp. as well as Striga hermonthica is associated with the presence of specific bacterial taxa, including Pseudomonas (Kawa et al, 2022 ; Zermane et al, 2007 ). Since, PGC‐producing Pseudomonas can be followed in soil via qPCR approaches (Almario et al, 2013 ), determining the correlation between the community of PGC‐producing Pseudomonas and the level of parasitic plant infection would bring new insights on the ecological role of these bacteria in suppressive soils.…”

“…This constitute the main problem to constrain their deleterious impact on crops (Haring & Flessner, 2018 ). The survival of the seeds depends on various abiotic factors (pH, humidity, climate) (Rubiales et al, 2003 ) and biotic factors (host plants, soil and rhizosphere microbiota; (Huet et al, 2020 ; Kawa et al, 2022 ; Martinez et al, 2023 ; Mutuku et al, 2021 ). Different agricultural strategies attempt to regulate broomrape populations in agroecosystems, such as crop rotation, triggering the suicidal germination of the plant parasitic seeds or the use of resistant host plant varieties or chemical herbicides (Cartry et al, 2021 ).…”

The genetic basis of plants’ battle against witchweeds: linking immune responses to distinct resistance mechanisms

“…Fungal isolates pathogenic to Striga have been successfully used in maize fields to reduce Striga infection ( Nzioki et al , 2016 ). Bacterial species degrading haustorium-inducing factors or inducing mechanical barriers in sorghum roots have been isolated ( Kawa et al , 2022 , Preprint). Additionally, using beneficial microorganisms as bioinoculants can promote plant health and inhibit Striga growth and attachment ( Jamil et al , 2021 ; Abdullahi et al , 2022 ).…”