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BACKGROUND: Striga hermonthica, an obligate root parasitic weed, poses a significant threat to cereal production in sub‐Saharan Africa. Lowering Striga seed bank in infested soils is a promising strategy to mitigate infestation levels. The dependency of Striga seed germination on strigolactones opens up the possibility of a 'suicidal germination' approach, where synthetic germination stimulants induce lethal germination in the absence of a host. Implementing this approach requires active germination stimulants with a suitable formulation for field application. Here, we describe the development of slow‐releasing granular formulation of two potent germination stimulants 'Methyl Phenlactonoate 3' and 'Nijmegen‐1' and the assessment of their activity under Laboratory, greenhouse, mini‐field, and field conditions. RESULTS: Under laboratory conditions, the granular formulation of either of the two germination stimulants (1.25 mg per plate, corresponding to 0.09 mg a.i.) induced Striga seed germination at a rate of up to 43%. With 10 mg granular product (0.75 mg a.i.) per pot, we observed 77–83% reduction in Striga emergence under greenhouse pot conditions. Application of the formulated stimulants under artificially or naturally infested fields resulted in approximately 56%, 60%, and 72% reduction in Striga emergence in maize, sorghum, and millet fields in Kenya and Burkina Faso, respectively. CONCLUSION: Our findings on the newly designed granular formulation of Methyl Phenlactonoate 3 and Nijmegen‐1 reveal encouraging prospects for addressing the Striga problem in Africa. These findings underscore several significant advantages of the formulated stimulants, including suitability for the African agricultural context, and, most importantly, their effectiveness in reducing Striga infection. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Pre‐attachment resistance to the parasitic plants Striga hermonthica and S. asiatica occurs in sorghum mutants designated low germination stimulant 1 (lgs1). However, only a few of these mutants have been identified and their resistance validated. Additionally, pre‐attachment resistance in sorghum beyond lgs1 mutants has not been explored. We used lgs1‐specific markers to identify new lgs1‐like mutants in a diverse global sorghum collection. The sorghum collection was also evaluated for pre‐attachment resistance against Striga using an in vitro assay that measured Striga germination activity and radicle growth. RESULTS: From a total of 177 sorghum accessions, 60 recorded mean germination levels of below 42%, which is comparable with the previously identified lgs1‐like sorghum (SRN39 and IS9830) used as controls in this study. Furthermore, 32 of these accessions recorded Striga radicle lengths comparable or lower than the controls (0.42 mm). Thirty‐eight accessions contained the lgs1 mutation and although overall, lgs1 mutants had considerably reduced Striga germination, some low inducers of Striga germination were wild‐type for lgs1. Germination was positively but weakly correlated with radicle length pointing to additional radicle growth inhibitory activity. CONCLUSIONS: lgs1 mutations, alongside other mechanisms for low Striga germination stimulation, are prevalent in sorghum, and poor Striga radicle growth is suggestive of host‐derived inhibition. As an outcome, our study makes available multiple Striga‐resistant sorghum with adaptability to diverse agro‐ecological regions in sub‐Saharan Africa making immediate deployment possible. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Biological crop pests cause serious economic losses. In Africa, the most prevalent parasites are insect pests, plant pathogenic root-knot nematodes, viruses and parasitic plants. African smallholder farmers struggle to overcome these parasitic constraints to agricultural production. Crop losses and the host range of these parasites have continued to increase in spite of the use of widely advocated control methods. A sustainable method to overcome biological pests in Africa would be to develop crop germplasm resistant to parasites. This is achievable using either genetic modification (GM) or a non-GM approach. However, there is a paucity of resistant genes available for introduction. Additionally, the biological processes underpinning host parasite resistance are not sufficiently well understood. The authors review a technology platform for using RNA-mediated interference (RNAi) as bioengineered resistance to important crop parasites in Africa. To achieve acquired resistance, a host crop is stably transformed with a transgene that encodes a hairpin RNA targeting essential parasitic genes. The RNAi sequence is chosen in such a way that it shares no homology with the host's genes, so it remains 'inactive' until parasitism. Upon parasitism, the RNAi sequence enters the parasite and post-transcriptional gene silencing (PTGS) mechanisms are activated, leading to the death of the parasite. Copyright © 2010 Society of Chemical Industry [ABSTRACT FROM AUTHOR]