Biology subjects

Ahmed, H. I.

Publications and source records attributed to Ahmed, H. I..

4 recordsLinked to original sources

bioRxiv2023

Origin and evolution of the bread wheat D genome

Bread wheat (Triticum aestivum) is a globally dominant crop and major source of calories and proteins for the human diet. Compared to its wild ancestors, modern bread wheat shows lower genetic diversity caused by polyploidisation, domestication, and breeding bottlenecks1,2. Wild wheat relatives represent genetic reservoirs, harbouring diversity and beneficial alleles that have not been incorporated into bread wheat. Here, we establish and analyse pangenome resources for Tauschs goatgrass, Aegilops tauschii, the donor of the bread wheat D genome. This new pangenome facilitated the cloning of a disease resistance gene and haplotype analysis across a complex disease resistance locus, allowing us to discern alleles from paralogous gene copies. We also reveal the complex genetic composition and history of the bread wheat D genome, involving previously unreported contributions from genetically and geographically discrete Ae. tauschii subpopulations. Together, our results reveal the complex history of the bread wheat D genome and demonstrate the potential of wild relatives in crop improvement.

genomics↗

bioRxiv2023

Deciphering Salt Stress Responses in Solanum pimpinellifolium through High-Throughput Phenotyping.

Soil salinity is a major environmental stressor affecting agricultural productivity worldwide. Understanding plant responses to salt stress is crucial for developing resilient crop varieties. Wild relatives of cultivated crops, such as wild tomato, Solanum pimpinellifolium, can serve as a useful resource to further expand the resilience potential of the cultivated germplasm, S. lycopersicum. In this study, we employed high-throughput phenotyping in the greenhouse and field conditions to explore salt stress responses of a S. pimpinellifolium diversity panel. Our study revealed extensive phenotypic variations in response to salt stress, with traits such as transpiration rate, shoot mass, and ion accumulation showing significant correlations with plant performance. We found that while transpiration was a key determinant of plant performance in the greenhouse, shoot mass strongly correlated with yield under field conditions. Conversely, ion accumulation was the least influential factor under greenhouse conditions. Through a Genome Wide Association Study, we identified candidate genes not previously associated with salt stress, highlighting the power of high-throughput phenotyping in uncovering novel aspects of plant stress responses. This study contributes to our understanding of salt stress tolerance in S. pimpinellifolium and lays the groundwork for further investigations into the genetic basis of these traits, ultimately informing breeding efforts for salinity tolerance in tomato and other crops.

plant biology↗

bioRxiv2020

Fonio millet genome unlocks African orphan crop diversity for agriculture in a changing climate

Sustainable food production in the context of climate change necessitates diversification of agriculture and a more efficient utilization of plant genetic resources. Fonio millet (Digitaria exilis) is an orphan African cereal crop with a great potential for dryland agriculture. Here, we established high-quality genomic resources to facilitate fonio improvement through molecular breeding. These include a chromosome-scale reference assembly and deep re-sequencing of 183 cultivated and wild Digitaria accessions, enabling insights into genetic diversity, population structure, and domestication. Fonio diversity is shaped by climatic, geographic, and ethnolinguistic factors. Two genes associated with seed size and shattering showed signatures of selection. Most known domestication genes from other cereal models however have not experienced strong selection in fonio, providing direct targets to rapidly improve this crop for agriculture in hot and dry environments.

plant biology↗

bioRxiv2018

Evidence for the Modulation of the Immune Response in Peripheral Blood Mononuclear Cells after Stimulation with a High Molecular Weight β-glucan Isolated from Lactobacillus fermentum Lf2

Lactobacillus fermentum Lf 2 produces large amounts of exopolysaccharides under optimized conditions ([~]2 g/L, EPS) which have been shown to possess immunomodulatory activity. In this study, the crude EPS was fractionated to give a high molecular weight (HMw) homoglycan and a mixture of medium molecular weight heteroglycans. The HMw EPS was isolated and identified as a {beta}-glucan.\n\nPeripheral blood mononuclear cells (PBMC) were pre-treated with purified polysaccharide to determine if the HMw {beta}-glucan is responsible for the immunomodulatory activity. Cells were also stimulated with either lipopolysaccharide (LPS) or phytohemagglutinin (PHA) and their effects, both with and without {beta}-glucan pre-treatment, compared.\n\nExposure of the cells to {beta}-glucan increased their metabolic activity and whilst a small but statistically significant drop in CD14 expression was observed at Day 1, the levels were significantly elevated at Day 2. High levels of CD14 expression were observed in cells initially exposed to the {beta}-glucan and subsequently stimulated with either LPS or PHA. In contrast, reduced levels of TLR-2 expression were observed for cells initially exposed to the {beta}-glucan and subsequently stimulated with LPS.\n\nTNF- levels were elevated in {beta}-glucan treated cells (Day1) with the levels dropping back once the {beta}-glucan had been removed (Day 2). The stimulants LPS and PHA both induced significant rises in TNF- levels, however, this induction was completely (LPS) or partially blocked (PHA) in {beta}-glucan pre-treated cells.\n\nThe results indicate a role for the bacterial {beta}-glucan in modulating the immune response following exposure to agonists such as bacterial LPS.

microbiology↗