Biology subjects

Laforest, M.

Publications and source records attributed to Laforest, M..

3 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↗

bioRxiv2021

Insights from the genomes of four diploid Camelina spp.

Plant evolution has been a complex process involving hybridization and polyploidization making understanding the origin and evolution of a plants genome challenging even once a published genome is available. The oilseed crop, Camelina sativa (Brassicaceae), has a fully sequenced allohexaploid genome with three unknown ancestors. To better understand which extant species best represent the ancestral genomes that contributed to C. sativas formation, we sequenced and assembled chromosome level draft genomes for four diploid members of Camelina: C. neglecta C. hispida var. hispida, C. hispida var. grandiflora and C. laxa using long and short read data scaffolded with proximity data. We then conducted phylogenetic analyses on regions of synteny and on genes described for Arabidopsis thaliana, from across each nuclear genome and the chloroplasts to examine evolutionary relationships within Camelina and Camelineae. We conclude that C. neglecta is closely related to C. sativas sub-genome 1 and that C. hispida var. hispida and C. hispida var. grandiflora are most closely related to C. sativas sub-genome 3. Further, the abundance and density of transposable elements, specifically Helitrons, suggest that the progenitor genome that contributed C. sativas sub-genome 3 maybe more similar to the genome of C. hispida var. hispida than that of C. hispida var. grandiflora. These diploid genomes show few structural differences when compared to C. sativas genome indicating little change to chromosome structure following allopolyploidization. This work also indicates that C. neglecta and C. hispida are important resources for understanding the genetics of C. sativa and potential resources for crop improvement.

genomics↗

bioRxiv2021

Winter rye cover cropping changes squash (Cucurbita pepo) phyllosphere microbiota and reduces Pseudomonas syringae symptoms

Cover cropping is a soil conservation practice that may reduce the impacts of the economically important pathogen Pseudomonas syringae on crops including squash (Cucurbita pepo). To date, no studies have directly quantified the effect of rye cover crops on P. syringae populations, nor on the bacterial community of squash leaves. In this work, we tested the hypothesis that the protective effects of cover cropping on squash may be mediated by cover cropping effects on the plants microbiota that in turn protects against P. syringae. Using combined 16S sequencing and culture-based approaches, we showed that rye cover cropping protects squash against P. syringae, by decreasing pathogen population size on squash leaves and increasing fruit health and marketability at harvest. We also found evidence of a strong effect of rye cover crops on bacterial communities of the squash phyllosphere. Those findings were more striking early in the growing season. Finally, we identified numerous phyllosphere bacteria belonging to the genera Sphingomonas, Methylobacterium and Pseudomonas that were promoted by rye cover crops. Overall, our findings suggest cover cropping is effective for the sustainable management of P. syringae on squash and may provide a reservoir of potential microbial biocontrol agents colonizing the phyllosphere.

ecology↗