Explore the vast range of titles available.

The impact of modern agriculture on the evolutionary trajectory of plant pathogens is a central question for crop sustainability. The Green Revolution replaced traditional rice landraces with high-yielding varieties, creating a uniform selection pressure that allows measuring the effect of such intervention. In this study, we analyzed a unique historical pathogen record to assess the impact of a major resistance gene, Xa4 , in the population structure of Xanthomonas oryzae pv. oryzae ( Xoo ) collected in the Philippines in a span of 40 years. After the deployment of Xa4 in the early 1960s, the emergence of virulent pathogen groups was associated with the increasing adoption of rice varieties carrying Xa4 , which reached 80% of the total planted area. Whole genomes analysis of a representative sample suggested six major pathogen groups with distinctive signatures of selection in genes related to secretion system, cell-wall degradation, lipopolysaccharide production, and detoxification of host defense components. Association genetics also suggested that each population might evolve different mechanisms to adapt to Xa4 . Interestingly, we found evidence of strong selective sweep affecting several populations in the mid-1980s, suggesting a major bottleneck that coincides with the peak of Xa4 deployment in the archipelago. Our study highlights how modern agricultural practices facilitate the adaptation of pathogens to overcome the effects of standard crop improvement efforts.

Rice production in Sub-Saharan Africa (SSA) faces significant challenges due to insect pest infestations, which threaten food security and farmer livelihoods. This review examines the major insect pests affecting rice in SSA and highlights sustainable management strategies, drawing on successful case studies. It explores successful methods, including the use of biological control agents in Nigeria; neem-based pesticides in Tanzania; push-pull technology in Kenya; agroecological practices in Mali; resistant rice varieties in Ghana and Nigeria; integrated farming systems in Liberia, Guinea Conakry, Nigeria, Kenya and Madagascar; and farmer field schools in Zambia. Emerging technologies such as biotechnology and precision agriculture offer further additional opportunities to enhance pest control when effectively integrated within existing IPM frameworks. However, financial constraints, limited awareness, policy-related challenges, and inadequate infrastructure continue to limit widespread adoption. In this context, the review identifies critical research gaps, including the need for region-specific solutions, improved biopesticides, and long-term assessment of sustainable practices. Policy recommendations call for greater government investments, capacity-building programs, supportive regulatory environments, and stronger collaboration among researchers, development partners, and local stakeholders. Addressing these challenges can foster resilient and sustainable rice production systems across SSA.

Rice yellow mottle virus (RYMV) is a major pathogen of rice in Africa. RYMV has a narrow host range limited to rice and a few related poaceae species. We explore the links between the spread of RYMV in East Africa and rice history since the second half of the 19 th century. The phylogeography of RYMV in East Africa was reconstructed from coat protein gene sequences (ORF4) of 335 isolates sampled over two million square kilometers between 1966 and 2020. Dispersal patterns obtained from ORF2a and ORF2b, and full-length sequences converged to the same scenario. The following imprints of rice cultivation on RYMV epidemiology were unveiled. RYMV emerged in the middle of the 19 th century in the Eastern Arc Mountains where slash-and-burn rice cultivation was practiced. Several spillovers from wild hosts to cultivated rice occurred. RYMV was then rapidly introduced into the nearby large rice growing Kilombero valley and Morogoro region. Harvested seeds are contaminated by debris of virus infected plants that subsist after threshing and winnowing. Long-distance dispersal of RYMV is consistent (i) with rice introduction along the caravan routes from the Indian Ocean Coast to Lake Victoria in the second half of the 19 th century, (ii) seed movement from East Africa to West Africa at the end of the 19 th century, from Lake Victoria to the north of Ethiopia in the second half of the 20 th century and to Madagascar at the end of the 20 th century, (iii) and, unexpectedly, with rice transport at the end of the First World War as a troop staple food from the Kilombero valley towards the South of Lake Malawi. Overall, RYMV dispersal was associated to a broad range of human activities, some unsuspected. Consequently, RYMV has a wide dispersal capacity. Its dispersal metrics estimated from phylogeographic reconstructions are similar to those of highly mobile zoonotic viruses.

Rice is the main food crop for people in low- and lower-middle-income countries in Asia and sub-Saharan Africa (SSA). Since 1982, there has been a significant increase in the demand for rice in SSA, and its growing importance is reflected in the national strategic food security plans of several countries in the region. However, several abiotic and biotic factors undermine efforts to meet this demand. Rice yellow mottle virus (RYMV) caused by Solemoviridae is a major biotic factor affecting rice production and continues to be an important pathogen in SSA. To date, six pathogenic strains have been reported. RYMV infects rice plants through wounds and rice feeding vectors. Once inside the plant cells, viral genome-linked protein is required to bind to the rice translation initiation factor [eIF(iso)4G1] for a compatible interaction. The development of resistant cultivars that can interrupt this interaction is the most effective method to manage this disease. Three resistance genes are recognized to limit RYMV virulence in rice, some of which have nonsynonymous single mutations or short deletions in the core domain of eIF(iso)4G1 that impair viral host interaction. However, deployment of these resistance genes using conventional methods has proved slow and tedious. Molecular approaches are expected to be an alternative to facilitate gene introgression and/or pyramiding and rapid deployment of these resistance genes into elite cultivars. In this review, we summarize the knowledge on molecular genetics of RYMV-rice interaction, with emphasis on host plant resistance. In addition, we provide strategies for sustainable utilization of the novel resistant sources. This knowledge is expected to guide breeding programs in the development and deployment of RYMV resistant rice varieties.

Rice blast, caused by (teleomorph: Magnaporthe oryzae), is one of the most economically damaging diseases affecting rice worldwide. While the evolutionary origins and genetic structures of Asian and European P. oryzae populations are relatively well characterized, African isolates remain underexplored. This knowledge gap impedes the development of informed management strategies for rice blast in the region. The present study was conducted to characterize the genetic origins, population structure, admixture, demographic history, and effector gene diversity of P. oryzae isolates in SSA, and to elucidate their evolutionary trajectories and implications for disease management. A total of 180 genome sequences (45 from SSA, 135 from other regions) were analyzed using population genomic approaches. Phylogeographic reconstructions, demographic modeling, and genome-wide association studies were performed to trace migration events, quantify genetic diversity, and identify candidate adaptation genes. Effector gene repertoires were also examined for diversity and selection signatures. Our findings provide new dates for the divergence of SSA populations from Asian populations. The introduction of P. oryzae into Africa occurred mainly from China in the late 19th century, initially in West Africa (WA; Mali and Burkina Faso), and subsequently in Uganda and Madagascar during the early 20th century, before extending to the wider African region, with subsequent repeated introductions. Tajima's D and demographic modeling suggested complex population dynamics shaped by migration and asymmetric founder events, highlighting considerably shared genetic ancestry between Asia and East Africa (EA), in contrast with that between Asia and WA. Genome-wide association analysis identified a specific set of single nucleotide polymorphism markers, along with several candidate genes linked to adaptation. Effector analysis revealed that SSA isolates harbor fewer effectors and exhibit lower genetic diversity than Asian populations, with some effectors under positive selection, particularly in WA. P. oryzae populations in SSA are shaped by historical introductions, founder events, and region-specific adaptation processes. While WA populations have diverged significantly from their Asian ancestors, gene flow within SSA connects regional populations, and effector gene diversity reflects both conserved virulence strategies and adaptation to local hosts. Overall, this study improves the existing knowledge on P. oryzae populations in SSA and underscore the need for integrated management strategies that consider both historical and contemporary pathogen dynamics in Africa.

RNA‐binding protein interactions with viral RNA are crucial in the context of viral infections, as viral RNAs can recruit and reprogram host RNA‐binding proteins (RBPs) during disease progression. Despite their significance, the repertoire of RBPs involved in most viral infections remains inadequately characterized. In Africa, Sobemovirus Rice yellow mottle virus (Sobemovirus RYMV) is the most prevalent virus infecting rice, and its devastating impact has led to extensive research efforts worldwide. Comprehensive identification of host RBPs that are enriched under Sobemovirus RYMV‐infected conditions through RNA‐bound proteome (RBPome)‐wide studies could provide novel strategies for developing Sobemovirus RYMV resistance. In this study, a silica‐based acidic phase separation approach was employed to elucidate changes in the RBPome following Sobemovirus RYMV infection. The analysis demonstrated that Sobemovirus RYMV infection remodels the RBPome, with 11 non‐viral RBPs identified as significantly enriched and two non‐viral RBPs that were significantly less abundant following infection. This study provides a snapshot of the landscape of RBPome changes in response to Sobemovirus RYMV. Validating these RBPs to understand their biological involvement in Sobemovirus RYMV infection is crucial to developing Sobemovirus RYMV‐resistant rice varieties.

Mycotoxins such as aflatoxins (AFs), fumonisins (FBs), zearalenone (ZEN), and deoxynivalenol (DON) pose a risk to public health due to their carcinogenic potency (AFs and FBs) and anti-nutritional effects. The hazards associated with mycotoxins are accentuated where food management practices, control, and regulatory systems from farm to plate are sub-optimal. Information on the frequency of these mycotoxins in rice commercialized in markets in sub-Sahara Africa (SSA) is limited. The current study examined AF concentrations in 527 rice samples collected from 54 markets in five SSA countries. Grain quality characteristics, processing methods, and origin of samples were contrasted with toxin levels. In total, 72% of the samples had detectable AFs levels (range = 3.0 to 89.8 µg/kg). Forty-seven percent (47%) of the samples had AFs above 4 µg/kg, the European Union maximum level (ML), and were evaluated for cooccurrence with FBs, ZEN, and DON. Total AFs and ZEN cooccurred in 40% of the samples, and 30% of the positive ZEN samples had concentrations above the ML of 75 µg/kg. Total AFs did not co-occur with FBs and DON. Multivariate analysis revealed that length-to-width ratio ( p  < 0.0001), mixed variety for width ( p  = 0.04), and chalkiness ( p  = 0.009) significantly influenced aflatoxin concentrations. Slender grains had higher AFs concentrations than bold and medium grains ( p  < 0.0001). Possible strategies to mitigate mycotoxin contamination in rice include improving grain quality traits and practicing proper drying and hermetic storage before and after milling. These findings provide valuable insights for both domestic and international actors in establishing and strengthening regulations and management systems to mitigate rice mycotoxin contamination.