Biology subjects

Kawa, D.

Publications and source records attributed to Kawa, D..

6 recordsLinked to original sources

bioRxiv2025

Developing future resilience from signatures of adaptation across the sorghum pangenome

While the green revolution adapted a handful of crops to homogenous and high-input industrialized agriculture, much of the global population still relies on local food production from low-input smallholder farms that grow highly variable crop cultivars. The high diversity of the grain and bioenergy crop sorghum 1-4, and many other crops that were not homogenized during the green revolution 5, not only provides the raw materials for breeders to make substantial gains in cultivar improvement, but also constrains breeding efforts due to highly specialized locally adapted plant phenotypes 6. Here, we construct a 33-member pangenome and identify trait-associated variants in 1,988 cultivars and landraces. We then apply these resources to explore the complex interplay between historical contingency, ongoing adaptation, and the potential for future gains through climate-aware genome-enabled breeding. Specifically, our analyses conclusively demonstrate that multiple nested, deeply diverged, and previously uncharacterized structural variants in the domestication gene SHATTERING1 distinguish the previously established multicentric origin of sorghum. We then apply landscape genomics tests to reveal how gene flow, adaptation, and secondary contact created the complex genetic mosaic in current global breeding networks. Further analysis of climate-gene associations highlights candidate loci underlying adaptation, including the biosynthetic gene cluster for the cyanogenic glucoside dhurrin. Combined, the pangenome-informed variants developed here will enable both trait discovery and subsequent marker assays to accelerate breeding and provide a framework for similar applications in other diverse and non-model crops.

genomics↗

bioRxiv2024

Dissecting the genetic regulation of lateral root development in tomato under salt stress

Roots are the primary site for sensing salt, making them critical to understanding how plants adapt to salinity. Unraveling the genetic and molecular mechanisms that maintain root growth under salt stress is essential for developing resilient crops. Tomatoes are vulnerable to salinity, as over 50% of arable land is projected to become saline by 2050. While salt stress effects on tomato seed germination, shoot growth, and fruit yield are well-documented, the genetic basis of root development under salinity remains underexplored. Previous studies focused on physiological responses of roots in a narrow range of cultivated-tomatoes, overlooking the genetic diversity for salt resilience in wild-relatives like Solanum pimpinellifolium. Here, we investigated salt-induced changes in root system architecture (RSA) across a natural diversity panel of 220 wild- and 25 cultivated-tomato varieties. We identified tolerant accessions with different RSA strategies; prioritizing lateral root elongation versus emergence. To identify genes involved in specific aspects of lateral root development, an F1 hybrid was generated that exhibited both parents combined characteristics. An F2-segregating population was then used to identify four distinct subpopulations for Bulk Segregant Analysis (BSA). Simultaneously, we conducted Genome-Wide-Association Studies (GWAS) on root architecture of wild-tomato accessions under salt stress. By integrating the results of BSA and GWAS, we identified 22 candidates involved in the maintenance of root architecture. We utilized RNA-Seq to examine transcriptome reprogramming of the 22 genes in tomato accessions with contrasting lateral root responses. This approach resulted in the identification of 2 genes, AP2-like-ethylene-responsive transcription factor TOE3 and L-ascorbate peroxidase. Using exogenous ethylene, we demonstrated that root architecture exhibits plasticity, which benefits the plant by reducing Na+ accumulation. We profiled H2O2 waves across root systems of tomatoes, emphasizing the role of ROS in maintaining root system architecture under salt stress. These findings provide novel genetic targets for enhancing salt resilience in tomatoes, opening avenues for future research and breeding programs.

plant biology↗

bioRxiv2023

Root branching in salt requires auxin-independent modulation of LBD16 function

Salinity stress constrains lateral root (LR) growth and severely impacts plant growth. Auxin signaling is indispensable for the regulation of LR formation. Nevertheless, the molecular mechanism of how salinity affects root auxin signaling and whether salt would steer alternative pathway(s) to regulate LR development is unknown. Here we show that the auxin-regulated transcription factor LATERAL ORGAN BOUNDARY DOMAIN (LBD)16, known as an essential player for LR development under control conditions, is regulated by an alternative non-canonical pathway under salinity. Salt represses auxin signaling but in parallel activates an upstream transcriptional activator of LBD16, ZINC FINGER OF ARABIDOPSIS THALIANA 6 (ZAT6). ZAT6 modulates the activity of LBD16 to contribute to downstream cell wall remodeling, and promotes LR development under salinity stress. Our study thus shows that root developmental plasticity in response to salt stress is achieved by integration of auxin-dependent repressive and salt-activated auxin-independent pathways converging on LBD16 to modulate root branching modulation under salinity.

plant biology↗

bioRxiv2022

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

Sorghum bicolor is 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 weed Striga 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.

plant biology↗

bioRxiv2021

Characterization of growth and development of sorghum genotypes with differential susceptibility to Striga hermonthica

Variation in strigolactone composition in sorghum root exudates underlies its resistance to the parasitic weed, Striga hermonthica. Root exudates of the Striga susceptible variety Shanqui Red (SQR) contain primarily 5-deoxystrigol, which has a high efficiency of inducing Striga germination. SRN39 roots primarily exude orobanchol, leading to reduced Striga germination and making this variety resistant to Striga. This structural diversity in exuded strigolactones is determined by the polymorphism in the LGS1 (LOW GERMINATION STIMULANT 1) locus. Yet, the effects of the lgs1 mutation as well as the consequences of the vast genetic diversity between SQR and SRN39 have not been addressed in terms of growth and development. Here, we demonstrate additional consequences of LGS1 loss-of-function by phenotypic and molecular characterization. A suite of genes related to metabolism was differentially expressed between SQR and SRN39. Increased levels of gibberellin precursors in SRN39 were accompanied with its slower growth rate and developmental delay and we observed an overall increased SRN39 biomass. The slow-down in growth and differences in transcriptome profiles of SRN39 were strongly associated with plant age. Additionally, analyses of multiple LGS1 loss-of-function genotypes indicated that strigolactone stereochemistry influences root system architecture. In summary, we demonstrate that the consequences of the lgs1 mutation reach further than the changes in strigolactone profile in the root exudate and translate into alterations in growth and development. HighlightSRN39 and Shanqui Red are models for sorghum genotypes that are resistant and susceptible, respectively, to Striga hermonthica. Additional differences in plant growth, development, and hormone abundance should be considered when assessing Striga tolerance.

plant biology↗

bioRxiv2020

Innovation, conservation and repurposing of gene function in plant root cell type development

Plant species have evolved myriads of solutions to adapt to dynamic environments, including complex cell type development and regulation. To understand this diversity, we profiled tomato root cell type translatomes and chromatin accessibility. Using xylem differentiation in tomato, relative to Arabidopsis, examples of functional innovation, repurposing and conservation of transcription factors are described. Repurposing and innovation of genes are further observed within an exodermis regulatory network and illustrate its function. Translatome analyses of rice, tomato and Arabidopsis tissues suggest that root meristems are more conserved, and that the functions of constitutively expressed genes are more conserved than those of cell type/tissue-enriched genes. These observations suggest that higher-order properties of cell type and pan-cell type regulation are conserved between plants and animals. One Sentence SummaryPan-species cell type translatome and chromatin accessibility data reveal novelty, conservation and repurposing of gene function.

genomics↗