Striga Research Articles

The plant growth regulator zaxinone is essential for proper rice growth and development. Additionally, zaxinone and its two synthetic mimics, MiZax3 and MiZax5, have been shown to significantly promote crop growth and reduce infestation by the root parasitic plant Striga by suppressing strigolactone (SL) production, highlighting their potential for field application. Here, we developed 4 new MiZax through structural modifications of the methoxybenzene ring in MiZax3 and evaluated their effects on plant growth and SL exudation. These newly developed mimics enhanced rice growth and reduced SL release without compromising the bioactivity of the lead compound MiZax3. Our findings underscore their potential to guide future chemical design efforts aimed at exploring zaxinone biology.

Crop diversification is one of the strategies for sustainable intensification that hold promise for reducing poverty and ending hunger in communities that derive livelihood from farming. Intensification of smallholder systems require identification of companion crops that are amenable to intercropping within existing crop and farming systems, add economic/marketable value, are a source of food, and provide ecosystem services not currently provided in existing crop or farming systems. Push-pull is a companion cropping system that involves intercropping cereal crops with forage legumes in the (e.g. Desmodium), and planting a forage grass (e.g. Brachiaria) around this intercrop to control stem borer, suppress witch weed (striga) in maize-based systems. This study evaluated the performance of push-pull system when further intensified with Cajanas cajan (pigeon pea). Four treatments were set up on farmers’ plots in Kisumu, Siaya and Vihiga counties during the long and short rain seasons in 2021, 2022 and 2023: (1) conventional push-pull, (2) push-pull with (pigeon pea), (3) maize and pigeon pea, and (4) maize mono-crop. Crop growth and striga weed density were monitored in 20×10 m plots demarcated in each treatment during the growing season. Data on maize growth, number and vigour of striga weed were recorded on all plants within sub-plots measuring 2x2 m for four seasons. Results show that integration with pigeon pea further suppresses striga weed and does not affect growth and yield of maize. Pigeon pea could be a potential alternative crop for weed management in smallholder farming systems, where it can serve as a source of firewood and fodder.

In sub-Saharan Africa (SSA), maize (Zea mays L.) is both a cash crop and an important staple crop. However, Striga hermonthica infection constrains its production and productivity. A total of 159 hybrids from 21 international trials were evaluated under Striga-infested (STRINF) and Striga non-infested (STRNON) conditions at Mokwa and Abuja, Nigeria, from 2010 to 2021. The data were used to (i) determine the genetic enhancements in grain yield and Striga adaptive traits and (ii) assess the repeatability of the trials in identification of promising hybrids. Significant annual genetic gains in grain yield of 3.40% and 3.71% with increases of 76.87 and 127.02 kg ha - 1 yr - 1 were recorded under STRINF and STRNON conditions, respectively. The genetic gains in grain yield were associated with 3.04 and 2.25% decreases in Striga damage ratings at 8 and 10 weeks after planting (WAP), respectively, and 1.27% in the number of emerged Striga plants at 10 WAP. The results indicated that ears per plant and flowering dates had the highest consistency in repeatability estimates while the number of emerged Striga plants at 8 and 10 WAP recorded the lowest consistency in repeatability estimates. Generally, substantial progress has been achieved with a good level of repeatability estimates for the early maturing maize hybrid trials evaluated under STRINF and STRNON conditions.Those results have demonstrated that the breeding strategies adopted during the 12-year breeding period have been effective, and that the potential of the trials in the exploration of the genetic potential of the hybrids for commercialization in the SSA for food security and poverty alleviation.

In the plant-plant pathosystem of rice (Oryza sativa) and the parasitic plant Striga hermonthica, cell walls from either plant are important defensive and offensive structures. Here, we reveal the cell wall dynamics in both Striga and rice using simultaneous RNA sequencing. We used weighted gene co-expression network analysis to home in on cell wall modification processes occurring in interactions with a resistant rice cultivar (Nipponbare) compared with a susceptible one (IAC 165). Likewise, we compared the cell wall dynamics in Striga infecting resistant and susceptible rice. Our study revealed an intense battlement at the Striga-rice cell walls involving both parasite (offense) and host (defense) factors, the outcome of which makes the difference between successful or failed parasitism. Striga activates genes encoding cell wall-degrading enzymes to gain access to the host, expansins to allow for cell elongation, and pectin methyl esterase inhibitors for rigidity during infection. In the susceptible host, immune response processes are not induced, and Striga-derived cell wall-degrading enzymes easily breach the host cell wall, resulting in successful parasitism. In contrast, the resistant host invokes immune responses modulated by phytohormones to fortify the cell wall through polysaccharides and lignin deposition. Through these processes, the cell wall of the resistant host successfully obstructs parasite entry. We discuss the implications of these findings in the context of practical agriculture in which cell wall modification can be used to manage parasitic plants. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Societal Impact StatementThe root‐parasitic plant Striga hermonthica can cause severe crop failure, leading to significant agricultural and economic losses in Africa. Despite the promising target offered by the Striga seed germination mechanism for developing control methods, effective control methods have yet to be established. For seed germination, Striga must undergo an incubation under warm and humid conditions, a process termed conditioning, which allows it to germinate. Here, we report that the plant hormone gibberellin stimulates the conditioning process in Striga seeds. Our findings suggest that the quantitative control of gibberellin in plants is a promising approach for controlling Striga infestations and may help alleviate substantial threats to food security.Summary The root‐parasitic plant S. hermonthica is a serious agricultural threat in Africa. Although a number of control methods have been employed to combat Striga, there is still a need to develop more effective control methods. Striga seeds germinate only in the presence of host plants, owing to the need for host‐released stimulants, primarily strigolactone. To detect signals from the host, Striga seeds must be exposed to a specific warm, dark, and moist environment, which is known as conditioning. Gibberellin directly promotes germination in many nonparasitic plants, but Striga seeds are insensitive to exogenous gibberellin. Consequently, the role of gibberellin in the germination of Striga seeds is unclear. We demonstrated that the effect of the gibberellin biosynthesis inhibitor paclobutrazol was higher in seeds during the conditioning, compared with those already conditioned, suggesting that gibberellin primarily regulates conditioning rather than germination. The content of an active form gibberellin, gibberellin A4 (GA4) exhibited an increase throughout the conditioning period, and we quantified the elevated expression levels of some gibberellin biosynthesis genes. The GA4 treatment shortened the conditioning period required for strigolactone‐induced seed germination. We also discovered that gibberellin upregulated ShACO1, the gene responsible for ethylene synthesis, during conditioning, and that the inhibition of GR24‐induced germination by the ethylene biosynthesis inhibitor α‐aminoisobutyric acid was gradually alleviated by GA4. Our findings demonstrate that gibberellin is critical for conditioning and germination processes but acts as a minor stimulant in Striga seeds. This study demonstrates the potential of quantitative endogenous gibberellin control for Striga management, providing valuable insights for alleviating food security issues.

Abstract Striga hermonthica (Del.) Benth infestation is one of the major constraints to maize production in the Nigeria savannas. The application of nitrogen fertilizer to Striga-resistant hybrids may reduce Striga infection and increase grain yields. The objective of this study was to assess the performance of six maize hybrids at low (30 kg ha−1) and high (120 kg ha−1) nitrogen application under natural infestation with Striga in northern Nigeria in 2014 and 2015. The two nitrogen rates and the six hybrids were arranged in a split-plot design with three replications. The nitrogen treatment was assigned to the main plot while the maize hybrids were assigned to the subplot. Data were collected on number of emerged Striga plants, Striga damage score, total dry matter and grain yield. Results showed that the application of nitrogen at 120 kg ha−1 reduced the number of Striga plants by 58% compared to application at 30 kg N ha−1 in Kafin Madaki and by 48% in Tudun Wada. Nitrogen application at 120 kg N ha−1 also reduced Striga damage rating by 22% in Kafin Madaki and by 33% in Tudun Wada. Both the commercial hybrid (OBASUPER 1) and the susceptible hybrid (8338-1) exhibited higher Striga damage ratings compared to the new hybrids at both locations. Grain yield was 86 and 98% higher in Kafin Madaki and Tudun Wada, respectively, when N was applied at 120 kg N ha−1 than at 30 kg N ha−1. The hybrids M1124-3 and M1227-14 produced grain yields that were significantly higher than those of the other hybrids in all locations. Our results showed that the application of 120 kg N ha−1 to Striga-resistant maize hybrids will reduce Striga infection and increase grain yield.

Striga hermonthica (Del.) Benth., a parasitic weed, causes substantial yield losses in maize production in sub-Saharan Africa. Breeding for Striga resistance in maize is constrained by limited genetic diversity for Striga resistance within the elite germplasm and phenotyping capacity under artificial Striga infestation. Genomics-enabled approaches have the potential to accelerate identification of Striga resistant lines for hybrid development. The objectives of this study were to evaluate the accuracy of genomic selection for traits associated with Striga resistance and grain yield (GY) and to predict genetic values of tested and untested doubled haploid maize lines. We genotyped 606 doubled haploid lines with 8,439 rAmpSeq markers. A training set of 116 doubled haploid lines crossed to 2 testers was phenotyped under artificial Striga infestation at 3 locations in Kenya. Heritability for Striga resistance parameters ranged from 0.38-0.65 while that for GY was 0.54. The prediction accuracies for Striga resistance-associated traits across locations, as determined by cross-validation (CV) were 0.24-0.53 for CV0 and from 0.20 to 0.37 for CV2. For GY, the prediction accuracies were 0.59 and 0.56 for CV0 and CV2, respectively. The results revealed 300 doubled haploid lines with desirable genomic estimated breeding values for reduced number of emerged Striga plants (STR) at 8, 10, and 12 weeks after planting. The genomic estimated breeding values of doubled haploid lines for Striga resistance-associated traits in the training and testing sets were similar in magnitude. These results highlight the potential application of genomic selection in breeding for Striga resistance in maize. The integration of genomic-assisted strategies and doubled haploid technology for line development coupled with forward breeding for major adaptive traits will enhance genetic gains in breeding for Striga resistance in maize.

Sorghum is the most important crop grown in Burkina Faso and is a staple food for millions of people in rural areas. However, sorghum grain production is mainly from local varieties which are low yielding. Introduced exotic varieties were high yielding but low adopted due to bad grain quality for local dishes. Therefore, it is important to popularize new varieties that meet farmer’s needs. We assessed the agronomic performance and stability of 12 sorghum varieties in different agro-ecological zones in Burkina Faso. Studies were conducted in one location (Kamboinse research station) during 2022 and in six locations (Farako-Bâ, Kamboinse, Fada, Sabou, Zoula and Andemtenga) during rainy season 2023. Twelve sorghum varieties including checks (Kapelga, ICSV 1049) were evaluated in a randomized complete block design with genotypes as studied factors. Agromorphological parameters along with midge damage and number of Striga plants were collected in all the sites. Genotypes, environments and genotype × environment interactions were significant for heading time and grain yield. The varieties had different heading times and different grain yields within environments and across the six environments. The GGE biplot discriminated the study areas into a unique mega-environment for heading time and three mega-environments for yield potential. The majority of varieties yielded more than the average sorghum yield in sub-Sahara Africa, however low yielding varieties were found in environments affected by biotic and abiotic constraints. Some high yielding varieties (Sariaso 43 = 3960.94 kg/ha, 014-SB-EPDU-1004 = 3681.64kg/ha, Sariaso 42 = 3478,52 kg/ha and Sariaso 39 = 3427.73 Kg/ha) were clearly identified in constraintless mega-environments of Kamboinse and Farako-Ba. In conclusion, the GGE biplot analysis revealed that Sariaso 43 was the best genotype that combined suitable heading time and high grain yield across environments. The best performing genotypes for heading time were Sariaso 39 and PR3009B for grain yield. Identified high yielding varieties will be submitted for released and cultivation in suitable agro climatic areas.

The endemic parasitic witch weeds (Striga spp.), which are found throughout sub-Saharan Africa, including Ethiopia, are progressively expanding their geographic range and degree of infection, which is significantly decreasing crop productivity. They are currently regarded as a widespread blight. The fight for economic expansion and food security is weakened by the Striga issue. Countries where Striga was only beginning to spread 25 years ago are now seeing significant annual losses in agricultural productivity. The projected yearly loss of sorghum in SSA due to Striga is 22–27%, and in Ethiopia, it is 25%. In SSA, Striga causes an annual loss of \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\$7 billion in grains, of which \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\$75 million is Ethiopia's portion. A significant biotic limitation and substantial danger to the production of food for subsistence in Ethiopia is Striga. The predominant species is Striga hermonthica, which is most severe in severely degraded regions of the country's north, northwest, and east, including Tigray, Wollo, Gonder, Gojjem, North Shewa, and Eastern Hararghe. Because of its wide geographic distribution and devastating effects on millions of people's livelihoods, Striga is quickly growing into a pandemic of significant proportions in the nation. Diverse sorghum germplasm may be found in Ethiopia, where there is also a chance to create Striga-resistant cultivars.

Evaluation of push-pull technology for pest and soil fertility management on maize in north western Ethiopia

Genome-wide association studies reveals new candidate genes associated with resistance to Striga gesneroides in Cowpea [Vigna unguiculata (L.) Walp.] accessions from sub-Saharan Africa

Sorghum is important staple food for feeding humans and animals in sub-Saharan African country. Nowadays, with the advent of climate change couple to the population growth, the crop is faced to new challenges wish are gradually affecting the productivity. In Niger, a dry land country where farmers are growing sorghum at a small scale for family subsistence, the crop is confronted to biotic and abioticonstraints including nutrient deficiency in the soil. Among those constraint, Striga is the one that causes huge damage to sorghum cultivation through yield reduction. In addition, nutrient depletion in the soil are causing weed progresses in farmer’s field at a large scale. In fact, to overcome Striga problem several control methods have been successfully tested, but some of them are efficient but not accessible to farmers. It is important to control the weed by using effective and accessible way for smallholder farme in Niger. The main objective of this study was to assess the effectiveness of different doses of sesame (0, 0.5 and 1.5 g) and DAP (0, 2 and 5 g) on Striga impact and sorghum grain yield. Two (2) grammes micro dosing utilization of DAP shows good result in Striga plant emergency and distribution along sorghum field. Concerning the three doses of sesame seed involve in this experiment, the micro dosing two (1.5 g) positively affect Striga effect. The combination sesame seed and DAP can significantly reduce Striga impact on sorghum cultivation and increased sorghum grain yield.

BackgroundMany parasitic plants of the genera Striga and Cuscuta inflict huge agricultural damage worldwide. To form and maintain a connection with a host plant, parasitic plants deploy virulence factors (VFs) that interact with host biology. They possess a secretome that represents the complement of proteins secreted from cells and like other plant parasites such as fungi, bacteria or nematodes, some secreted proteins represent VFs crucial to successful host colonisation. Understanding the genome-wide complement of putative secreted proteins from parasitic plants, and their expression during host invasion, will advance understanding of virulence mechanisms used by parasitic plants to suppress/evade host immune responses and to establish and maintain a parasite-host interaction.ResultsWe conducted a comparative analysis of the secretomes of root (Striga spp.) and shoot (Cuscuta spp.) parasitic plants, to enable prediction of candidate VFs. Using orthogroup clustering and protein domain analyses we identified gene families/functional annotations common to both Striga and Cuscuta species that were not present in their closest non-parasitic relatives (e.g. strictosidine synthase like enzymes), or specific to either the Striga or Cuscuta secretomes. For example, Striga secretomes were strongly associated with ‘PAR1’ protein domains. These were rare in the Cuscuta secretomes but an abundance of ‘GMC oxidoreductase’ domains were found, that were not present in the Striga secretomes. We then conducted transcriptional profiling of genes encoding putatively secreted proteins for the most agriculturally damaging root parasitic weed of cereals, S. hermonthica. A significant portion of the Striga-specific secretome set was differentially expressed during parasitism, which we probed further to identify genes following a ‘wave-like’ expression pattern peaking in the early penetration stage of infection. We identified 39 genes encoding putative VFs with functions such as cell wall modification, immune suppression, protease, kinase, or peroxidase activities, that are excellent candidates for future functional studies.ConclusionsOur study represents a comprehensive secretome analysis among parasitic plants and revealed both similarities and differences in candidate VFs between Striga and Cuscuta species. This knowledge is crucial for the development of new management strategies and delaying the evolution of virulence in parasitic weeds.

Background and AimsInfection by the hemi-parasitic plant Striga hermonthica causes severe host plant damage and seed production losses. Increased availability of essential plant nutrients reduces infection. Whether, how and to what extent it also reduces striga-induced host plant damage has not been well studied.MethodsThe effects of improved macro- and micronutrient supply on host plant performance under striga-free and infected conditions were investigated in glasshouse pot assays. One striga-sensitive and two striga-tolerant genotypes were compared. Plants growing in impoverished soils were supplied with (1) 25 % of optimal macro- and micronutrient quantities, (2) 25 % macro- and 100 % micronutrients, (3) 100 % macro- and 25 % micronutrients, or (4) 100 % macro- and micronutrients.Key ResultsPhotosynthesis rates of striga-infected plants of the sensitive genotype increased with improved nutrition (from 12.2 to 22.1 μmol m−2 s−1) but remained below striga-free levels (34.9–38.8 μmol m−2 s−1). For the tolerant genotypes, increased macronutrient supply offset striga-induced photosynthesis losses. Striga-induced relative grain losses of 100 % for the sensitive genotype were reduced to 74 % by increased macronutrients. Grain losses of 80 % in the tolerant Ochuti genotype, incurred at low nutrient supply, were reduced to 5 % by improved nutrient supply.ConclusionsIncreasing macronutrient supply reduces the impact of striga on host plants but can only restore losses when applied to genotypes with a tolerant background.

Seeds of the root parasitic plant Striga hermonthica undergo a conditioning process under humid and warm environments before germinating in response to host-released stimulants, particularly strigolactones (SLs). The plant hormone abscisic acid (ABA) regulates different growth and developmental processes, and stress response; however, its role during Striga seed germination and early interactions with host plants is under-investigated. Here, we show that ABA inhibited Striga seed germination and that hindering its biosynthesis induced conditioning and germination in unconditioned seeds, which was significantly enhanced by treatment with the SL analog rac-GR24. However, the inhibitory effect of ABA remarkably decreased during conditioning, confirming the loss of sensitivity towards ABA in later developmental stages. ABA measurement showed a substantial reduction of its content during the early conditioning stage and a significant increase upon rac-GR24-triggered germination. We observed this increase also in released seed exudates, which was further confirmed by using the Arabidopsis ABA-reporter GUS marker line. Seed exudates of germinated seeds, containing elevated levels of ABA, impaired the germination of surrounding Striga seeds in vitro and promoted root growth of a rice host towards germinated Striga seeds. Application of ABA as a positive control caused similar effects, indicating its function in Striga/Striga and Striga/host communications. In summary, we show that ABA is an essential player during seed dormancy and germination processes in Striga and acts as a rhizospheric signal likely to support host infestation.

Seed germination of a parasitic plant Striga hermonthica is elicited by strigolactones which are exuded from roots of host plants. Here, we describe a high-throughput germination assay and a method for visualizing in vivo strigolactone receptor functions with a fluorogenic probe.

The apocarotenoid zaxinone is a recently discovered regulatory metabolite required for proper rice growth and development. In addition, zaxinone and its two mimics (MiZax3 and MiZax5) were shown to have a remarkable growth-promoting activity on crops and a capability to reduce infestation by the root parasitic plant Striga through decreasing strigolactone (SL) production, suggesting their potential for application in agriculture and horticulture. In the present study, we developed a new series of MiZax via structural modification of the two potent zaxinone mimics (MiZax3 and MiZax5) and evaluated their effect on plant growth and Striga infestation. In general, the structural modifications to MiZax3 and MiZax5 did not additionally improve their overall performance but caused an increase in certain activities. In conclusion, MiZax5 and especially MiZax3 remain the likely most efficient zaxinone mimics for controlling Striga infestation.

Dormant seeds of a root parasitic plant Striga hermonthica sense strigolactones from host plants as environmental cues for germination. This process is mediated by diversified member of strigolactone receptors encoded by HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE2 genes. It is known that warm and moist treatment of seed conditioning gradually turns dormant Striga seeds competent to respond strigolactones, while the mechanism behind it has been poorly understood. In this report, we show that plant hormone gibberellins increase the strigolactone-competence by up-regulating mRNA expressions of the major strigolactone receptors during the conditioning period. This idea was supported by poor germination phenotype when gibberellin biosynthesis is depleted by paclobutrazol during conditioning. Moreover, live-imaging with fluorogenic strigolactone-mimic, yoshimulactone green W, revealed that paclobutrazol treatment during conditioning caused aberrant dynamics of strigolactone perception after germination. These observations revealed an indirect role of gibberellins to the seed germination in Striga, which is contrastive to their roles as dominant germination stimulating hormone in non-parasitic plants. We propose a model of how the role of gibberellins become indirect during the evolution of parasitism in plants. Our work also highlight the potential role for gibberellins in field application, for instance, elevating the sensitivity of the seeds towards strigolactones in the current suicidal germination approach to alleviate the agricultural threats caused by this parasite in Africa.

Societal Impact StatementWitchweeds, parasitic plants of the genus Striga, are nicknamed “cereal killers” because of their devastating destruction of Africa's most staple cereals, including maize, sorghum, millets, and upland rice. The parasite relies on biomolecules emitted from the host roots to germinate and therefore initiate its infectious lifecycle. Some sorghum varieties have evolved to not produce effective germination stimulants, making them resistant to the parasite. Here, the genetic factors that underpin Striga germination were assessed, followed by a discussion of how such knowledge can be used to develop new Striga management strategies through the disruption of host–parasite communication exchange.Summary Seeds of the parasitic plant Striga are dormant. They only germinate in response to biomolecules emitted from the host's root exudate, strigolactones (SL). But it is now emerging that Striga germination is a much more complex process regulated by crosstalk of hormone signaling pathways. To further understand the genetic basis of the communication exchange between Striga and its host sorghum, we performed a comparative transcriptomic analysis. We sought to identify major transcriptomic changes that define the germination process in Striga and a set of genes that may contribute to the differences in germination rates. Results showed that germination proceeds immediately after SL perception and is marked by a wave of transcriptional reprogramming to allow for metabolic processes of energy mobilization. Cluster analysis using self‐organizing maps revealed a time‐phased and genotype‐differentiated response to germination stimulation. The variation in germination was also a function of hormonal crosstalk. The early germination stage was associated with significant repression of genes in the abscisic acid (ABA) biosynthesis pathway. Other hormones influenced germination as follows: (i) ABA and auxin repressed germination; (ii) brassinosteroid, ethylene, and jasmonic acid promoted germination; and (iii) cytokinin had a more prominent role post‐germination rather than during germination. Perception of SL sets the germination program leading to different rates of germination in sorghum, followed by a complex hormonal regulation network that acts to either repress or enhance germination. We discuss the implications of these findings and present new plausible Striga management strategies.

Genetic underpinnings of host–pathogen interactions in the parasitic plant Striga hermonthica, a root parasitic plant that ravages cereals in sub-Saharan Africa, are unclear. We performed a comparative transcriptome study on five genotypes of sorghum exhibiting diverse resistance responses to S. hermonthica using weighted gene co-expression network analysis (WGCNA). We found that S. hermonthica elicits both basal and effector-triggered immunity—like a bona fide pathogen. The resistance response was genotype specific. Some resistance responses followed the salicylic acid-dependent signaling pathway for systemic acquired resistance characterized by cell wall reinforcements, lignification, and callose deposition, while in others the WRKY-dependent signaling pathway was activated, leading to a hypersensitive response. In some genotypes, both modes of resistance were activated, while in others either mode dominated the resistance response. Cell wall-based resistance was common to all sorghum genotypes but strongest in IS2814, while a hypersensitive response was specific to N13, IS9830, and IS41724. WGCNA further allowed for pinpointing of S. hermonthica resistance causative genes in sorghum, including glucan synthase-like 10 gene, a pathogenesis-related thaumatin-like family gene, and a phosphoinositide phosphatase gene. Such candidate genes will form a good basis for subsequent functional validation and possibly future resistance breeding.