Genome Analysis Of Endophytic Escherichia Coli USML2 And Its In Planta Ascending Migration With Growth Promoting Effect

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Date
2018-01
Authors
Tharek, Munirah
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Publisher
Universiti Sains Malaysia
Abstract
The discovery of E. coli USML2 from inner leaf tissues of healthy oil palm (Elaeis guineensis Jacq.) raised several questions regarding its presence in planta and benefits to the host plant. Therefore, the ability of E. coli USML2 to migrate from roots into internal leaf tissues of rice seedlings and promote growth of its host plant was investigated. Subsequently, analysis of E. coli USML2 genome was performed to elucidate genes related to in planta ascending migration and plant growth promotion. Finally, importance of in planta migration towards plant growth promotion was also studied. Based on the results, E. coli USML2 colonized the root surface and internal tissues of root, stem and leaf within 24 h of inoculation. Results also indicated an infection pattern initiated from root surface colonization, invasion of the internal root system followed by bacteria migration into the stem and leaf tissues. Interestingly, E. coli USML2 inoculation exhibited significant increase of leaf numbers (33.3%), chlorophyll content (33.3%), shoot height (34.8%) and plant dry weight (90.4%) of 42-days-old rice seedlings as compared to the negative control. Furthermore, analysis of E. coli USML2 genome revealed genes encoding for bacteria movement towards the root (flagella, chemotaxis), root adhesion (pili, quorum sensing, extracellular polymeric substances), invasion (cellulose and pectin degradation enzymes) and plant growth promotion (nitrogen, phosphorus, potassium, IAA, ACC, acetoin, siderophore, trehalose, sulphur, magnesium transporter, chorismate, choline, taurine, riboflavin, pyridoxine, phenylpropanoids, membrane transporters). Interestingly, genomic island predicted several in planta ascending migration (pili, EPS) and plant growth promotion (magnesium transporter, mgtC) genes. Additionally, genes involved in adhesion (uncharacterized protein YdeU and an outer membrane autotransporter barrel-domain containing protein) were among 24 unique genes in E. coli USML2.
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Escherichia coli USML2 in planta ascending migration , with growth promoting effect
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