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TECHNICAL SESSION: Characterization of crop-associated microbiome

Cultivar and environment influence on epiphytic bacterial diversity on wheat seeds.
Marilen Nampijja - South Dakota State University. Emmanuel Byamukama- South Dakota State Univ, Bruce Bleakley- South Dakota State University, Trinity Hamilton- University of Minnesota

Seeds are sources of inocula and can facilitate introduction of pathogens into the field. Therefore,it is important to determine seed microbiota to limit spread of plant pathogens. This study aimed to determine the bacterial diversity on wheat seeds as influenced by variety and location in South Dakota. Twenty grams of seed from three replicates of eight wheat varieties from Aurora and Volga were vortexed twice, sonicated for four minutes in a phosphate buffer suspension at pH of 7.4. Fifteen ml of the seed wash were used for DNA extraction and sequencing, while 5 ml were stored for biochemical tests. Sequencing was done at the University of Minnesota genomics laboratory using 16 S rRNA. The resultant sequences were analyzed using Mothur software. Alpha diversity indices such as Chao1, Simpsom, and Shannon determined species richness and evenness, while beta diversity determined diversity between locations and varieties. The taxa identified were Xylophilus, Sphingomonas, Pseudomonas, Plantibacter, Pedobcater, Neorrhizobium, Microbacterium, Methylobacterium, Massilia, Hymenobacter, Kinecoccus, muciliginabacter, Enterobacteriaceae, Curtobacterium and Chrysobacterium. Sphingomonas had a higher relative abundance compared to other genera in both locations while the genus that could harbor potential wheat pathogens was Pseudomonas. The varieties differed from each other in genera relative abundance while there was no significant location effect on relative abundance of the genera. Results indicate limited evidence that cultivar and environment influence bacteria diversity.