Articles
THE DEVELOPMENT OF SPINACH (SPINACIA OLERACEA) PHYLLO-EPIPHYTIC BACTERIAL COMMUNITY FROM SEED THROUGH MATURE LEAF STAGES IS INFLUENCED BY ENVIRONMENT
Article number
938_3
Pages
29 – 38
Language
English
Abstract
Recent disease outbreaks associated with vegetables, especially fresh spinach, have alarmed consumers, caused economic losses for vegetable producers, and raised questions about how pathogens are transmitted.
Little is known about bacteria associated with seeds and the contributions of the seed to the endophytic and epiphytic communities of the leaves (phyllosphere). The bacterial populations of spinach seed and on leaves of seedlings after seed germination, and from developing plants were compared using DGGE, to assess bacterial community richness, and real-time PCR to compare the abundance of select phyla (total bacteria, Actinobacteria, Bacteroidetes, Firmicutes, α-Proteobacteria and β-Proteobacteria). To determine the effect of environment, the plants were grown in field and growth chambers.
Vertical transmission of bacterial community members was evident; the developmental stage of the plant affected the richness and abundance of select bacterial phyla.
The bacterial richness of plants grown in the two environments was not affected.
However, overall numbers of bacteria were higher in field-grown samples in comparison to those produced in growth chambers.
A statistically significant interaction was seen between growth stage and environment with each of the selected phyla.
Bacteria populations colonizing cotyledons were smaller than those of mature leaves, but the differences were not significant with the 3-4 leaf-stage plants.
The culturable populations of bacteria on seeds (~5 log CFU/g) were significantly smaller than determined using real time PCR (~7 log copies). This study highlights the importance of vertical trans¬mission on the bacterial community colonizing plants and suggests that plants have adapted to transfer bacteria which are beneficial to their growth through the seed, possibly within the seed coat, embryo, or layers of endosperm.
Little is known about bacteria associated with seeds and the contributions of the seed to the endophytic and epiphytic communities of the leaves (phyllosphere). The bacterial populations of spinach seed and on leaves of seedlings after seed germination, and from developing plants were compared using DGGE, to assess bacterial community richness, and real-time PCR to compare the abundance of select phyla (total bacteria, Actinobacteria, Bacteroidetes, Firmicutes, α-Proteobacteria and β-Proteobacteria). To determine the effect of environment, the plants were grown in field and growth chambers.
Vertical transmission of bacterial community members was evident; the developmental stage of the plant affected the richness and abundance of select bacterial phyla.
The bacterial richness of plants grown in the two environments was not affected.
However, overall numbers of bacteria were higher in field-grown samples in comparison to those produced in growth chambers.
A statistically significant interaction was seen between growth stage and environment with each of the selected phyla.
Bacteria populations colonizing cotyledons were smaller than those of mature leaves, but the differences were not significant with the 3-4 leaf-stage plants.
The culturable populations of bacteria on seeds (~5 log CFU/g) were significantly smaller than determined using real time PCR (~7 log copies). This study highlights the importance of vertical trans¬mission on the bacterial community colonizing plants and suggests that plants have adapted to transfer bacteria which are beneficial to their growth through the seed, possibly within the seed coat, embryo, or layers of endosperm.
Authors
M. Ponder, P. Carder, G. Lopez-Velasco, G.E. Welbaum
Keywords
phyllosphere, epiphytic bacteria, microbial community, phylloplane
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