Comparison of the Bacterial Community Naturally Occurring On Spinach Seeds and the Plants Produced From Those Seeds.

Seeds planted for crop production are known to be populated with bacteria, yeast, fungi, and viruses.  Some seed-borne microorganisms are pathogenic, while others are harmless and some actually benefit plants by competing with plant pathogens for space and nutrients.  To date, the role the seed microbiota plays in the establishment of the microbial community on the plant leaves at different stages of plant development is largely unexplored.  The microbial communities from spinach seeds and the plants produced from those seeds were compared to determine the importance of the seed microflora on the development of the phyllosphere microflora at various stages of spinach development. Spinach was grown in a greenhouse.  Microbial communities from seed, cotyledon, 2-3 leaf stage and 6-8 leaf stages of development were extracted using commercial kits.  The bacterial members were amplified using 16s rDNA primers for Denaturing Gel Electrophoresis (DGGE).  The microbial communities were compared based on similarity between DGGE profiles. The majority of the spinach microbial community was conserved throughout the stages of plant development.  However, at each stage of plant development unique bands, corresponding to a species were present.  The least diverse microbial community was seen on the cotyledons, as several bands were absent that were present in the seed and 2-3 leaf stage communities.  The community profiles were most diverse for 6-8 and 2-3 leaf stage plants. The stage of plant development does affect richness of the microbial community of the spinach phyllosphere as determined by DGGE.