Agriculture and Agri-Food Canada

About: Agriculture and Agri-Food Canada is a facility organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Soil water. The organization has 10921 authors who have published 21332 publications receiving 748193 citations. The organization is also known as: Department of Agriculture and Agri-Food.

ROS accumulation and antiviral defence control by microRNA528 in rice.

Abstract: MicroRNAs (miRNAs) are key regulators of plant-pathogen interactions. Modulating miRNA function has emerged as a new strategy to produce virus resistance traits1-5. However, the miRNAs involved in antiviral defence and the underlying mechanisms remain largely elusive. We previously demonstrated that sequestration by Argonaute (AGO) proteins plays an important role in regulating miRNA function in antiviral defence pathways6. Here we reveal that cleavage-defective AGO18 complexes sequester microRNA528 (miR528) upon viral infection. We show that miR528 negatively regulates viral resistance in rice by cleaving L-ascorbate oxidase (AO) messenger RNA, thereby reducing AO-mediated accumulation of reactive oxygen species. Upon viral infection, miR528 becomes preferentially associated with AGO18, leading to elevated AO activity, higher basal reactive oxygen species accumulation and enhanced antiviral defence. Our findings reveal a mechanism in which antiviral defence is boosted through suppression of an miRNA that negatively regulates viral resistance. This mechanism could be manipulated to engineer virus-resistant crop plants.

Fungal and Bacterial Abundance in Long-Term No-Till and Intensive-Till Soils of the Northern Great Plains

Abstract: Abundance of fungi and bacteria in long-term no-till (NT) and intensively tilled (IT) soils in the Northern Great Plains were measured using phospholipid fatty acid analysis (PLFA) to determine if a shift in the relative abundance of fungi and bacteria occurs as the result of conversion to NT. Four tillage trials located in four different soil zones were sampled in spring of 2005 and 2006 before the crop was seeded to evaluate the long-term effect of tillage on the microbial community. With the exception of one site-year, total, bacterial, and fungal PLFA were greater in NT than IT soils at the soil surface (0- to 5-cm depth) (p < 0.05). Increases ranged from 8 to 202% for total biomass, 26 to 58% for bacterial biomass, and 0 to 120% for fungal biomass. At one site (Ellerslie) all biomass measurements were greater in IT than NT in 2005 and bacterial biomass was also greater under IT in 2006. The influence of tillage on microbial biomass was less pronounced with depth. Fungal dominance is commonly assumed under NT; however, our results demonstrate that although biomass of both fungi and bacteria increase in NT, the abundance of fungi vs. bacteria was not consistently greater under NT in the soils studied. Further research is needed to determine if fungi may be able to exert a more functionally dominant role in NT soils without an increase in relative abundance.