• A critical review of integrated grass weed management in Ireland

      Byrne, Ricky; Spink, John; Freckleton, R.; Neve, Paul; Barth, Susanne; Teagasc Walsh Fellowship Programme (Teagasc (Agriculture and Food Development Authority), Ireland, 2018-04-10)
      Grass weeds affect arable crops throughout the world, inflicting yield penalties, reducing crop quality and taking available nutrients away from the growing crop. Recently in Ireland, the presence of herbicide resistance in grass weeds has been noted. In order to preserve the sustainability of crop production in Ireland, an integrated pest management approach must be implemented. How this applies to control grass weeds was the focus of this review. Here we examined the state of current research into grass weed biology and the nature of herbicide resistance, identifying gaps in research in the Irish context. We identified a number of cultural grass weed control techniques, as being relevant to the Irish mode of crop production. Crop rotation, cultivation techniques, manipulation of sowing dates and increased crop competition were recognised as useful strategies. Combining these strategies to provide effective grass weed control may be key to reduce dependence on herbicides.
    • Experimental comparison of two methods to study barley responses to partial submergence

      Miricescu, Alexandra; Byrne, Tomás; Doorly, Catherine M; Ng, Carl K Y; Barth, Susanne; Graciet, Emmanuelle; Department of Agriculture, Food and the Marine; Maynooth University Kathleen Lonsdale Institute for Human Health.; 14/S/819 (Biomed Central, 2021-04-13)
      Background Crop yield is dependent on climate conditions, which are becoming both more variable and extreme in some areas of the world as a consequence of global climate change. Increased precipitation and flooding events are the cause of important yield losses due to waterlogging or (partial) submergence of crops in the field. Our ability to screen efficiently and quickly for varieties that have increased tolerance to waterlogging or (partial) submergence is important. Barley, a staple crop worldwide, is particularly sensitive to waterlogging. Screening for waterlogging tolerant barley varieties has been ongoing for many years, but methods used to screen vary greatly, from the type of soil used to the time at which the treatment is applied. This variation makes it difficult to cross-compare results. Results Here, we have devised a scoring system to assess barley tolerance to waterlogging and compare two different methods when partial submergence is applied with either water or a starch solution at an early developmental stage, which is particularly sensitive to waterlogging or partial submergence. The use of a starch solution has been previously shown to result in more reducing soil conditions and has been used to screen for waterlogging tolerance. Conclusions Our results show that the two methods provide similar results to qualitatively rank varieties as tolerant or sensitive, while also affecting plants differently, in that application of a starch solution results in stronger and earlier symptoms than applying partial submergence with water.
    • Genome biology of the paleotetraploid perennial biomass crop Miscanthus

      Mitros, Therese; Barth, Susanne; Klaas, Manfred; U.S. Department of Energy; DE-SC0018420; DE-AC02-05CH11231.; 289461; DE-SC0006634; DE-SC0012379. (Nature, 2020-10-28)
      Miscanthus is a perennial wild grass that is of global importance for paper production, roofing, horticultural plantings, and an emerging highly productive temperate biomass crop. We report a chromosome-scale assembly of the paleotetraploid M. sinensis genome, providing a resource for Miscanthus that links its chromosomes to the related diploid Sorghum and complex polyploid sugarcanes. The asymmetric distribution of transposons across the two homoeologous subgenomes proves Miscanthus paleo-allotetraploidy and identifies several balanced reciprocal homoeologous exchanges. Analysis of M. sinensis and M. sacchariflorus populations demonstrates extensive interspecific admixture and hybridization, and documents the origin of the highly productive triploid bioenergy crop M. × giganteus. Transcriptional profiling of leaves, stem, and rhizomes over growing seasons provides insight into rhizome development and nutrient recycling, processes critical for sustainable biomass accumulation in a perennial temperate grass. The Miscanthus genome expands the power of comparative genomics to understand traits of importance to Andropogoneae grasses.
    • The occurrence of herbicide-resistant Avena fatua (wild oats) populations to ACCase-inhibiting herbicides in Ireland

      Byrne, R.; Vijaya Bhaskar, A.V.; Spink, J.; Freckleton, R.; Neve, P.; Barth, Susanne (Teagasc, 2021-06-03)
      Following growers’ reports of herbicide control problems, populations of 30 wild oats, Avena fatua, were collected from the south-east main arable counties of Ireland in 2016 and investigated for the occurrence and potential for herbicide resistance to acetyl-CoA carboxylase (ACCase) inhibitors pinoxaden, propaquizafop and cycloxydim, as well as acetolactate synthase (ALS) inhibitor mesosulfuron + iodosulfuron. Plant survival ≥20% was considered as the discriminating threshold between resistant and susceptible populations, when plants were treated with full recommended field rates of ACCase/ALS inhibitors. Glasshouse sensitivity screens revealed 2 out of 30 populations were cross-resistant to all three ACCase inhibitors. While three populations were cross-resistant to both pinoxaden and propaquizafop, and additionally, two populations were resistant to propaquizafop only. Different degree of resistance and cross-resistance between resistant populations suggest the involvement of either different point mutations or more than one resistance mechanism. Nevertheless, all populations including the seven ACCase-resistant populations were equally susceptible to ALS inhibitor. An integrated weed management (cultural/non-chemical control tactics and judicious use of herbicides) approach is strongly recommended to minimize the risk of herbicide resistance evolution.
    • Physiological and Transcriptional Response to Drought Stress Among Bioenergy Grass Miscanthus Species

      Vega, Jose J. De; Teshome, Abel; Klaas, Manfred; Grant, Jim; Finnan, John; Barth, Susanne; European Union; FP7-KBBE-2011-5-289461; CLNE/2017/364 (Biomed Central, 2020-07-28)
      Background: Miscanthus is a commercial lignocellulosic biomass crop owing to its high biomass productivity, particularly in the temperate regions. This study was conducted to elucidate physiological and molecular responses of four Miscanthus species subjected to well-watered and droughted greenhouse conditions. Results: A signicant biomass loss was observed under drought conditions for all genotypes. A sterile M. x giganteus showed a lower reduction in biomass yield under drought conditions compared to the control than the other species. Under well-watered conditions, biomass yield was as good as or better than control conditions in all species tested. M. sinensis was more tolerant than M. sacchariorus to both water stress conditions. 4,389 of the 67,789 genes (6.4%) in the reference genome were differentially expressed among four Miscanthus species. Most of the genes were differentially expressed in a single species, but the enrichment analysis of gene ontology (GO) terms revealed that the same biological processes were regulated in all the species during stress conditions. Namely, upregulated differentially expressed genes were signicantly involved in sucrose and starch metabolism, redox, and water and glycerol homeostasis and channel activity. Multiple copies of starch metabolic enzymes BAM and waxy GBSS-I were strongly up-regulated in drought stress in all Miscanthus genotypes. Twelve aquaporins (PIP1, PIP2 and NIP2) were also up-regulated in drought stress across genotypes. On the other hand, downregulated differentially expressed genes were signicantly involved in protein kinase activity, cell receptor signalling and phosphorylation. Conclusions: Findings in the present study can assist in implementing molecular breeding approaches of drought resistant Miscanthus and its domestication.