Biology subjects

Masanga, J.

Publications and source records attributed to Masanga, J..

6 recordsLinked to original sources

bioRxiv2025

Legacy of warming and microbial treatments shape root exudates and rhizosphere fungal communities of a tropical tree

O_LIPlant metabolites play a pivotal role in shaping rhizosphere microbial communities, yet how plant and microbial functions respond to environmental change remains poorly understood. We combined ecometabolomics and fungal community profiling to investigate how multiple abiotic and biotic treatments influence root exudate chemistry and fungal community assemblage in a tropical tree. C_LIO_LIGuarea guidonia seedlings were grown in sterilized soil primed with inoculum from long-term experimentally warmed or ambient plots in Puerto Rico. We manipulated soil microbes, soil moisture, and plant density and tested metabolite-fungi-plant trait associations. C_LIO_LIMetabolite diversity was significantly influenced by soil microbial legacy and moisture, while antimicrobial treatments altered metabolite composition without affecting diversity. Metabolite clusters exhibited distinct treatment-specific patterns. Fungal alpha diversity increased under low moisture, community composition shifted with antimicrobial treatments, and certain families showed strong treatment-specific responses. Although fungal diversity was not correlated with metabolite diversity, fungal community structure was significantly associated with metabolite composition. We also found global and pathway-specific correlations between fungal and metabolite distances, and weak but significant associations between metabolite/fungal composition and seedling traits. C_LIO_LIThese results underscore how environmental conditions shape belowground interactions, highlighting metabolite-fungal associations as potential early indicators of plant response to disturbance. C_LI

plant biology↗

bioRxiv2025

Strigolactone effects on Sorghum bicolor ecophysiology and symbioses

Strigolactones are ecologically, developmentally, and physiologically important hormones, but much remains unknown about their evolution and role in non-model species. Sorghum is a globally important C4 cereal and exhibits natural variation in root-exuded strigolactones. Differences in sorghum strigolactone stereochemistry are associated with resistance to parasitic plants, but with evidence for potential trade-offs. We studied sorghum mutants of loci in the strigolactone biosynthetic pathway, CAROTENOID CLEAVAGE DIOXYGENASE 8 (SbCCD8b) and LOW GERMINATION STIMULANT 1 (LGS1), previously shown to be Striga resistant by stimulating little germination of the parasite. SbCCD8b CRISPR-Cas9 deletions changed the accumulation of low abundance metabolites, reduced net carbon assimilation rate, altered root architecture and anatomy, and diminished the establishment and benefit of mycorrhizal symbionts. For Striga-resistant LGS1 CRISPR-Cas9 deletions, differentially expressed genes were enriched with promoter motifs for stress response and growth pathways, net carbon assimilation rate was reduced, and the colonization of mycorrhizal symbionts was delayed. We additionally restored functional LGS1 into the RTx430 genetic background, which normally has the lgs1-2 natural deletion allele. While root exudates from LGS1 insertion mutants rescued Striga susceptibility, we did not see consistent rescue of other traits impacted in LGS1 loss-of-function mutants. We hypothesize that epistasis with a neighboring strigolactone synthesis gene, which is rarely lost without concomitant loss of LGS1, may alter the phenotypic effects of LGS1 variation. Our study gives context to potential trade-offs associated with host resistance to parasitic plants and, more broadly, builds on the contribution of strigolactones in shaping sorghum physiological processes, growth, and development.

plant biology↗

bioRxiv2025

Delivering trait-enhanced varieties to African smallholders through a pangenomic breeding network

Pangenomics has been promoted to accelerate breeding of orphan crops, but smallholder farmers in developing nations have seen little benefit so far. To address this gap, we built a global pangenomic breeding network, integrating African breeding programs, U.S. land grant universities, and international nonprofit research organizations. Here we demonstrate that pangenomics, when integrated with local crop improvement knowledge and global scientific partnerships, can facilitate breeding of drought and pest resilient varieties for smallholders. To breed trait-enhanced sorghum varieties with lgs1-1 resistance to witchweed (Striga hermonthica) for smallholders in Niger, one of the worlds least developed nations, we used population genomics across local and global scales to develop lgs1-1 Striga resistance markers, and deployed them for rapid introgression of resistance into locally-preferred varieties. Genomic characterization, along with controlled experiments in laboratory, pot, field stations, and smallholder farms, confirmed lgs1-1 resistance was introgressed without loss of essential local-preference traits. New pangenomic resources, including global resequencing and graph pangenomes, further accelerated design of broadly-applicable markers. Unlocking the potential of pangenomics for stress-resilience breeding depended on stakeholder input, strong inference, South-led decision support software, and a dense collaborative network. The experience of the network provides a scalable roadmap for collaborative pangenomic breeding of trait-enhanced varieties for the worlds lowest-resourced farmers.

genomics↗

bioRxiv2025

Genomics of Root System Architecture Adaptation in Sorghum under Nitrogen and Phosphorus Deficiency

Plant root systems play a crucial role in water and nutrient uptake so understanding the genetic mechanisms underlying root architecture adaptation to the environment is key, particularly in non-model crops. Here, we investigate the diversity of root system architecture (RSA) in Sorghum bicolor under nitrogen (N) and phosphorus (P) deficiency. We used a globally diverse sorghum panel to identify single nucleotide polymorphisms (SNPs) associated RSA responses under N and P deficiency through a genome-wide association study (GWAS). RSA adaptation under P deficiency involved development of fine exploratory roots marked by increased total root length and fine root classes (root length diameter ranges 1 and2), coupled with reduced radial expansion. Under N deficiency, adaptation also involved suppression of root radial growth but without elongation. In both cases, reduced radial growth was marked by reduced surface area and volume, more dramatically for P than N deficiency. GWAS identified SNPs associated with these RSA adaptations, some of which were in regions encoding genes such as: ILR3-like, bHLH, and a LEUNIG homolog all with known roles in root growth regulation. These findings provide novel genetic insights into sorghum root adaptation to nutrient limitations and offer potential targets for breeding resource-efficient crop varieties. SummaryPlants absorb water and nutrients from the soil through their roots, yet for most crops, little is known about how root shape and structure adapt to stressful conditions such as poor soil fertility. In this study, we used a globally diverse collection of sorghum genotypes to investigate how sorghum roots respond to nitrogen and phosphorus deficiency. Specific genotypes showed strong root adaptations under these conditions, leading us to identify genetic factors significantly associated with these responses. Our findings improve our understanding of root adaptation to nutrient stress and highlight promising genetic targets for breeding more nutrient-efficient crops.

genomics↗

bioRxiv2024

Tropical Forest Soil Microbiome Modulates Leaf Heat Tolerance More Strongly Under Warming than Ambient Conditions

Tropical forests are increasingly threatened by climate change. Yet, it is still unclear how tropical plants respond to increasing temperatures. Leaf heat tolerance (LHT) in tropical plants is often at its upper limit, suggesting that climate change might negatively impact tropical forests. We hypothesized that intraspecific variation in this leaf trait might be associated with changes in the soil microbiome, which might also respond to climate. Specifically, we hypothesized that warming would increase LHT through changes in the soil microbiome: this study combined an in-situ tropical warming experiment with a shade house experiment in Puerto Rico. The shade house experiment consisted of growing seedlings of Guarea guidonia, a dominant forest species, under different soil microbiome treatments (reduced arbuscular mycorrhizal fungi, reduced plant pathogens, reduced microbes, and unaltered) and soil inoculum from the field experiment. Heat tolerance was determined using chlorophyll fluorescence (FV/Fm) on individual seedlings in the field and on pooled seedlings by pot in the shade house. We sequenced soil fungal DNA to analyze the impacts of the field and shade house treatments on the soil microbiome. In the field, seedlings from ambient temperature plots showed higher FV/Fm values under high temperatures (0.648 at 46 {degrees}C and 0.067 at 52 {degrees}C) than seedlings from the warming plots (0.535 at 46 {degrees}C and 0.031 at 52 {degrees}C). In the shade house, the soil microbiome treatments, which significantly influenced the fungal community composition, significantly influenced LHT. Reduction in fungal pathogen abundance and diversity altered FV/Fm before T50 for seedlings grown with soil inoculum from the warming plots but after T50 for seedlings grown with soil inoculum from the ambient plots. Our findings emphasize that the soil microbiome might play an important role in modulating the impacts of climate change on plants. Understanding and harnessing this relationship might be vital for mitigating the effects of warming on tropical forests, emphasizing the need for further research on microbial responses to climate change.

ecology↗

bioRxiv2020

Physiological and ecological warnings that Dodder pose an exigent threat to farmlands in Eastern Africa

Invasive holoparasitic plants of the genus Cuscuta (dodder) threaten Africas ecosystems, due to their rapid spread and attack on various host plant species. Most Cuscuta species cannot photosynthesize, hence rely on host plants for nourishment. After attachment through a peg-like organ called a haustorium, the parasites deprive hosts of water and nutrients leading to their death. Despite their rapid spread in Africa, dodders have attracted limited research attention, although data on their taxonomy, host range and epidemiology are critical for their management. Here, we combine taxonomy and phylogenetics to reveal presence of field dodder (Cuscuta campestris) and C. kilimanjari (both either naturalized or endemic to East Africa), and for the first time in continental Africa, presence of the giant dodder (C. reflexa) a south Asian species. These parasites have a wide host range, parasitizing species across 13 angiosperm orders. Evaluating the possibility of C. reflexa to expand this host range to tea, coffee, and mango, crops of economic importance to Africa, revealed successful parasitism, following haustorial formation and vascular bundle connections in all three crops. However, only mango mounted a successful post-attachment resistance response. Furthermore, species distribution models predicted high habitat suitability for all three Cuscuta species across major tea- and coffee-growing regions of Eastern Africa, suggesting an imminent risk to these crops. Our findings provide relevant insights into a little-understood threat to biodiversity and economic wellbeing in Eastern Africa, and providing critical information to guide development of management strategies to avert their spread. Sentence SummaryMicroscopy and habitat suitability modeling provide an early warning that dodders invasion in Eastern Africa poses a threat to important cash crops

ecology↗