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Conservation and diversity of seed associated endophytes in Zea across boundaries of evolution, ethnography and ecology.

Johnston-Monje D, Raizada MN - PLoS ONE (2011)

Bottom Line: Of these traits, phosphate solubilization and production of acetoin/butanediol were the most commonly observed.An isolate from the giant Mexican landrace Mixteco, with 100% identity to Burkholderia phytofirmans, significantly promoted shoot potato biomass.Conservation and diversity in Zea-microbe relationships are discussed in the context of ecology, crop domestication, selection and migration.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada.

ABSTRACT
Endophytes are non-pathogenic microbes living inside plants. We asked whether endophytic species were conserved in the agriculturally important plant genus Zea as it became domesticated from its wild ancestors (teosinte) to modern maize (corn) and moved from Mexico to Canada. Kernels from populations of four different teosintes and 10 different maize varieties were screened for endophytic bacteria by culturing, cloning and DNA fingerprinting using terminal restriction fragment length polymorphism (TRFLP) of 16S rDNA. Principle component analysis of TRFLP data showed that seed endophyte community composition varied in relation to plant host phylogeny. However, there was a core microbiota of endophytes that was conserved in Zea seeds across boundaries of evolution, ethnography and ecology. The majority of seed endophytes in the wild ancestor persist today in domesticated maize, though ancient selection against the hard fruitcase surrounding seeds may have altered the abundance of endophytes. Four TRFLP signals including two predicted to represent Clostridium and Paenibacillus species were conserved across all Zea genotypes, while culturing showed that Enterobacter, Methylobacteria, Pantoea and Pseudomonas species were widespread, with γ-proteobacteria being the prevalent class. Twenty-six different genera were cultured, and these were evaluated for their ability to stimulate plant growth, grow on nitrogen-free media, solubilize phosphate, sequester iron, secrete RNAse, antagonize pathogens, catabolize the precursor of ethylene, produce auxin and acetoin/butanediol. Of these traits, phosphate solubilization and production of acetoin/butanediol were the most commonly observed. An isolate from the giant Mexican landrace Mixteco, with 100% identity to Burkholderia phytofirmans, significantly promoted shoot potato biomass. GFP tagging and maize stem injection confirmed that several seed endophytes could spread systemically through the plant. One seed isolate, Enterobacter asburiae, was able to exit the root and colonize the rhizosphere. Conservation and diversity in Zea-microbe relationships are discussed in the context of ecology, crop domestication, selection and migration.

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Summary of functional traits exhibited by cultured seed endophytes grouped by bacterial genus.Light yellow shading indicates that <25% of isolates from the Zea genotype indicated exhibited the trait, deep yellow indicates 25–50%, orange indicates 50–75%, and red indicates 75–100%. A more detailed listing by isolate is included in Table S4.
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pone-0020396-g009: Summary of functional traits exhibited by cultured seed endophytes grouped by bacterial genus.Light yellow shading indicates that <25% of isolates from the Zea genotype indicated exhibited the trait, deep yellow indicates 25–50%, orange indicates 50–75%, and red indicates 75–100%. A more detailed listing by isolate is included in Table S4.

Mentions: Interestingly three genera of microbes which were widely culturable across Zea (Figure 7), Enterobacter, Pantoea and Pseudomonas, were found to significantly contribute to the most conserved endophytic traits (Figure 9). Of 63 isolates that solubilised phosphate, 51 belonged to these genera. Similarly, 28/49 acetoin producers belonged to Enterobacter and Pantoea. Finally, 18/27 bacteria that could grow on nitrogen-free media belonged to Enterobacter and Pseudomonas.


Conservation and diversity of seed associated endophytes in Zea across boundaries of evolution, ethnography and ecology.

Johnston-Monje D, Raizada MN - PLoS ONE (2011)

Summary of functional traits exhibited by cultured seed endophytes grouped by bacterial genus.Light yellow shading indicates that <25% of isolates from the Zea genotype indicated exhibited the trait, deep yellow indicates 25–50%, orange indicates 50–75%, and red indicates 75–100%. A more detailed listing by isolate is included in Table S4.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3108599&req=5

pone-0020396-g009: Summary of functional traits exhibited by cultured seed endophytes grouped by bacterial genus.Light yellow shading indicates that <25% of isolates from the Zea genotype indicated exhibited the trait, deep yellow indicates 25–50%, orange indicates 50–75%, and red indicates 75–100%. A more detailed listing by isolate is included in Table S4.
Mentions: Interestingly three genera of microbes which were widely culturable across Zea (Figure 7), Enterobacter, Pantoea and Pseudomonas, were found to significantly contribute to the most conserved endophytic traits (Figure 9). Of 63 isolates that solubilised phosphate, 51 belonged to these genera. Similarly, 28/49 acetoin producers belonged to Enterobacter and Pantoea. Finally, 18/27 bacteria that could grow on nitrogen-free media belonged to Enterobacter and Pseudomonas.

Bottom Line: Of these traits, phosphate solubilization and production of acetoin/butanediol were the most commonly observed.An isolate from the giant Mexican landrace Mixteco, with 100% identity to Burkholderia phytofirmans, significantly promoted shoot potato biomass.Conservation and diversity in Zea-microbe relationships are discussed in the context of ecology, crop domestication, selection and migration.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada.

ABSTRACT
Endophytes are non-pathogenic microbes living inside plants. We asked whether endophytic species were conserved in the agriculturally important plant genus Zea as it became domesticated from its wild ancestors (teosinte) to modern maize (corn) and moved from Mexico to Canada. Kernels from populations of four different teosintes and 10 different maize varieties were screened for endophytic bacteria by culturing, cloning and DNA fingerprinting using terminal restriction fragment length polymorphism (TRFLP) of 16S rDNA. Principle component analysis of TRFLP data showed that seed endophyte community composition varied in relation to plant host phylogeny. However, there was a core microbiota of endophytes that was conserved in Zea seeds across boundaries of evolution, ethnography and ecology. The majority of seed endophytes in the wild ancestor persist today in domesticated maize, though ancient selection against the hard fruitcase surrounding seeds may have altered the abundance of endophytes. Four TRFLP signals including two predicted to represent Clostridium and Paenibacillus species were conserved across all Zea genotypes, while culturing showed that Enterobacter, Methylobacteria, Pantoea and Pseudomonas species were widespread, with γ-proteobacteria being the prevalent class. Twenty-six different genera were cultured, and these were evaluated for their ability to stimulate plant growth, grow on nitrogen-free media, solubilize phosphate, sequester iron, secrete RNAse, antagonize pathogens, catabolize the precursor of ethylene, produce auxin and acetoin/butanediol. Of these traits, phosphate solubilization and production of acetoin/butanediol were the most commonly observed. An isolate from the giant Mexican landrace Mixteco, with 100% identity to Burkholderia phytofirmans, significantly promoted shoot potato biomass. GFP tagging and maize stem injection confirmed that several seed endophytes could spread systemically through the plant. One seed isolate, Enterobacter asburiae, was able to exit the root and colonize the rhizosphere. Conservation and diversity in Zea-microbe relationships are discussed in the context of ecology, crop domestication, selection and migration.

Show MeSH
Related in: MedlinePlus