Biology subjects

Jugulam, M.

Publications and source records attributed to Jugulam, M..

4 recordsLinked to original sources

bioRxiv2025

Determination of the mechanisms of MCPA resistance in Amaranthus powellii

Resistance to 2-methyl-4-chloro-phenoxyacetic acid (MCPA) was recently confirmed in a population of green pigweed (Amaranthus powellii) from Dresden, Ontario, Canada, with a resistance factor of 4.4. Resistance to synthetic auxin herbicides in Amaranthus species has previously been linked to non-target site resistance mechanisms with low-level resistance factors (<10). Based on this information an investigation into the mechanism of resistance to MCPA was conducted in this population of green pigweed. No significant differences in absorption, translocation, and metabolism of 14C-MCPA existed between the resistant and a susceptible population of green pigweed. An RNA-Sequencing experiment to identify differentially expressed genes also confirmed this result. Genes that were differentially expressed in the resistant population were linked to target site modifications. A single nucleotide polymorphism (SNP) conferring a leucine to phenylalanine substitution was identified in auxin response factor (ARF) 9. This mutation may be in the Phox and Bem1p (PB1) domain in ARF9 which facilitates the interaction between ARFs and Aux/IAA repressor proteins. The results demonstrate that the mechanism of resistance to MCPA is not a non-target site mechanism and may be linked to a target site modification. Specifically, a SNP in ARF9 could disrupt the interaction between ARF9 and other Aux/IAAs which could prevent ubiquitination of Aux/IAAs and subsequent lethal action of MCPA.

plant biology↗

bioRxiv2023

The International Weed Genomics Consortium: Community Resources for Weed Genomics Research

The International Weed Genomics Consortium is a collaborative group of researchers focused on developing genomic resources for the study of weedy plants. Weeds are attractive systems for basic and applied research due to their impacts on agricultural systems and capacity to swiftly adapt in response to anthropogenic selection pressures. Our goal is to use genomic information to develop sustainable and effective weed control methods and to provide insights about biotic and abiotic stress tolerance to assist crop breeding. Here, we outline resources under development by the consortium and highlight areas of research that will be impacted by these enabling resources.

genomics↗

bioRxiv2023

The eccDNA mediated spread and rapid evolution of herbicide resistance in pigweed interspecific hybrids

Extrachromosomal circular DNAs (eccDNAs) are found in many eukaryotic organisms. The eccDNA-powered copy number variation plays diverse roles from oncogenesis in humans to herbicide resistance in crop weeds. Here we report interspecific eccDNA flow and its dynamic behavior in soma cells of natural populations and F1 hybrids of Amaranthus sp. The glyphosate resistance (GR) trait is controlled by eccDNA-based amplification harboring the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene (EPSPS-eccDNA), the molecular target of glyphosate. We documented pollen-mediated transfer of eccDNA in experimental hybrids between GS A. tuberculatus x GR A. palmeri. Experimental hybridization and fluorescence in situ hybridization (FISH) analysis revealed that the EPSPS-eccDNA present in A. spinosus was derived from GR A. palmeri by natural hybridization. FISH analysis also revealed random chromosome anchoring and massive EPSPS-eccDNA copy number variation in soma cells of weedy hybrids. The results suggest that eccDNAs are inheritable across compatible species contributing to genome plasticity and rapid adaptive evolution.

genetics↗

bioRxiv2020

Resistance to tembotrione, a 4-hydroxyphenylpyruvate dioxygenase-inhibitor, in Sorghum bicolor

Postemergence grass weed control continues to be a big challenge in grain sorghum (Sorghum bicolor L. Moench), primarily due to a lack of herbicide options registered for use in this crop. The development of herbicide-resistant sorghum technology to facilitate broad-spectrum postemergence weed control is an economical and viable solution. The 4-hydroxyphenylpyruvate dioxygenase-inhibitor herbicides (e.g. mesotrione or tembotrione) can control broad-spectrum of weeds including grasses, which, however, is not registered for postemergence application in sorghum due to crop injury. In this study we identified two tembotrione-resistant sorghum genotypes (G-200, G-350) and one highly susceptible genotype (S-1) through screening 317 sorghum lines from the sorghum association panel (SAP). Compared to S-1, G-200 and G-350 exhibited 10- and 7-fold more resistance to tembotrione, respectively. Genetic analyses of the F1 and F2 progeny generated from a cross between tembotrione-resistant and -susceptible genotypes demonstrated that the resistance is a semi-dominant polygenic trait. Furthermore, cytochrome P450 (CYP)-inhibitor assay using malathion and piperonyl butoxide suggested possible CYP-mediated metabolism of tembotrione in G-200 and G-350. Genotype-by-sequencing based quantitative trait loci (QTL) mapping revealed eight QTLs associated with tembotrione resistance in grain sorghum. Sorghum genotypes G-200 and G-350 confer a high level of metabolic resistance to tembotrione and controlled by a polygenic trait. There is an enormous potential to introgress the tembotrione resistance into breeding lines to develop agronomically desirable sorghum hybrids. One-sentence summaryThis research focuses on characterization, genetic analyses, identification of QTLs-linked to metabolic resistance to tembotrione in Sorghum bicolor, for improved weed control and increased yield

plant biology↗