This is the report from a BSPP Undergraduate ‘Vacation’ Bursary.
Click here to read more/apply for one yourself.
Cover crops have been shown to have numerous benefits for soil health and the success of subsequent crops. Previous research has demonstrated benefits to soil nutrition and retention, soil structure and a reduction in soil erosion. Recent studies have also indicated that cover crops may also play an important role in disease suppression, both directly and indirectly. This project will contribute to a wider study by Scotland’s Rural College (SRUC) investigating the interactions between various cover crop species and soil-borne pathogens in a field trial of spring barley. Barley is Scotland’s predominant cereal crop, with a significant proportion of the crop used in the production of malt for the whisky distilling industry. The yield and quality of barley can be affected by diseases such as Fusarium Head Blight (FHB), caused by soil-borne pathogens Fusarium spp. and Microdochium spp. This project aims to investigate whether cover crop species and associated tillage regime have an effect on the species of Fusarium found on a subsequent spring barley crop or in the local soil microbiome.
Thirty-two plots of untreated spring barley (cv Laureate) were selected from a larger field trial, each having previously been planted with a cover crop of either hairy vetch, oil radish, mustard, or left fallow. Weather conditions during the early phase of the project were unusually hot and dry (generally poor conditions for soil-borne pathogens) and no visual symptoms of Fusarium were observed on stem bases. The planned visual disease assessments were therefore cancelled, and plant sampling for molecular identification of fungal species was carried out instead. Plant stem base samples and soil samples were collected from the trial field plots and taken to the lab for processing and DNA extraction.
The plant stem bases were cut to 2 cm long and freeze dried for 48 hours, before being macerated and ground with liquid nitrogen. Following DNA extraction a multiplex conventional PCR with primers for Fusarium avenaceum, F. culmorum, F. graminearum, and F. poae was carried out. Gel-electrophoresis was then used to determine if any of the Fusarium species were detected in the samples. The plant stem base PCR runs were successful and provided interesting results. Fifty percent of the asymptomatic plant samples from conventionally tilled plots, and fifty six percent from minimum tillage plots contained Fusarium, with F. culmorum being by far the most prevalent. F. avenaceum was only found in minimum tillage plots and was not detected in conventionally ploughed plots. The results indicated some potential differences between Fusarium prevalence between cover crop species, although not enough to be statistically significant.
The collected soil samples were oven dried at 30⁰C for 96 hours before being blended. A commercially available DNA extraction kit for soils, followed by a DNA cleaning and concentrating protocol were used before the same Fusarium multiplex PCR to see if the same species could be identified in the surrounding soil. Unfortunately, none of the soil samples returned positive results for the four Fusarium species, potentially due to an excess of other DNA or degradation. Soil samples will instead be sent away for next-generation sequencing (NGS) to build a better profile of the soil microbial communities.
This undergraduate vacation bursary project has been an extremely useful and enjoyable experience for me, and I’m extremely grateful to the BSPP for funding the project. I’m thankful to my supervisors Dr Helen Rees and Dr Maciej Kaczmarek for helping me conduct the research and develop my lab skills, as well as providing their insight into what working in academia is like. I’d also like to thank the technicians and staff at SRUC who have helped me with sample collection and processing, DNA extraction, PCR, isolation, culturing and sub-culturing, and more. This experience has really spurred me on to continue research in plant pathology for my honours project and hopefully onto post-graduate research in the future.
James Douglass
Scotland’s Rural College and The Royal Botanic Garden Edinburgh
This is the report from a BSPP Undergraduate ‘Vacation’ Bursary.
Click here to read more/apply for one yourself.
