ISHS Acta Horticulturae 917: XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Plant Protection
ALTERATIONS TO THE PHYLLOEPIPHYTIC BACTERIAL COMMUNITY OF SPINACH WITH LEAF AGE |
| Authors: | H. Tydings, G. Lopez-Velasco, M. Ponder, G. Welbaum |
| Keywords: | phyllosphere, epiphytic bacteria, microbial community |
| DOI: | 10.17660/ActaHortic.2011.917.27 |
| Abstract:
There is a numerous and diverse bacterial community residing on the phyllo¬epiphytic surface of plants. Some of these bacteria are pathogenic, while others benefit plants by providing additional nutrients and competing with plant pathogens for space and nutrients. The members of these communities are likely to be established early in plant development, likely just after leaf emergence. It is currently unknown how the age of the leaf affects the numbers and diversity of bacteria residing on the phylloepiphytic surface. Three cultivars of spinach were grown within growth chambers to minimize the numbers of transient bacteria acquired from air. Each leaf was numbered after emerging from six plants per cultivar, grown until the six-leaf development stage. Microbial communities from the leaves of each emergence stage from the six plants were removed by stomaching of the leaves in sterile saline. Microbial counts were performed by serial dilution and plated onto R2A media. The bacterial members were amplified from extracted DNA using 16s rDNA primers containing a GC clamp to allow for subsequent analysis by denaturing gradient gel electrophoresis (DGGE). The bacterial communities were compared based on simi¬larity between DGGE profiles. Numbers of culturable bacteria varied from 103-106 colony forming units (CFU)/g of spinach leaf. The largest numbers of bacteria were present on newly emerged leaves; however, comparable numbers of bacteria were present on the oldest three leaves. The community profiles of bacteria from each cultivar were 60% similar. Profiles of newly emerged leaves were most similar to each other. Profiles of communities were most similar between older leaves of the same cultivar (70-90%). The richness and abundance of the spinach phyllosphere bacterial community decreases as the plant leaf matures, likely due to decreased nutrient availability of the leaf surface. | |
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