USF Scholarship: a digital repository @ Gleeson Library | Geschke Center
Abstract
As the human population continues to grow, there is an increasing realization that there is a finite amount of land available to grow enough food to feed people in the long-term. Sustainable agriculture is one key part of the solution to this issue. One technique used in sustainable agriculture is cover cropping, which involves the planting of a non-cash crop that is used to restore nutrients or structure within the soil. Although these benefits of cover cropping are well documented, the effect that this practice has on the reduction of pathogens on cash crops has yet to be fully explored. Even though endophytes (asymptomatic microbes living inside of plant tissues) live cryptically within their plant host, they have also been noted to help reduce the disease symptoms of their plant host. If the relationship between endophytes and pathogens could be better understood, these interactions could be used to aid in pathogen reduction. Our objective is thus to quantify which bacterial taxa inhabit the leaves of cover crops (purple vetch, Vicia americana; daikon radish, Raphanus sativus var. longipinnatus; and fava beans, Vicia faba) in an organic agricultural setting. In coordination with a working farm in Marin County, California (Star Route Farms), we sampled cover crop leaves prior to the start of the cash crop growing season. Leaves were surface sterilized with dilute bleach and ethanol and leaf fragments were placed into slant tubes with malt extract agar to isolate emergent foliar bacteria. Microbial slant tube growth was quantified, and bacterial isolates were identified using 16S Sanger sequencing and BLAST queries of the NCBI Genbank database. The results from this research could provide a new technique for improving agricultural sustainability and could also contribute towards a better ecological understanding of these complex and economically critical agricultural systems
