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Mining the phytomicrobiome to understand how bacterial coinoculations enhance plant growth.

Maymon M, Martínez-Hidalgo P, Tran SS, Ice T, Craemer K, Anbarchian T, Sung T, Hwang LH, Chou M, Fujishige NA, Villella W, Ventosa J, Sikorski J, Sanders ER, Faull KF, Hirsch AM - Front Plant Sci (2015)

Bottom Line: In previous work, we showed that coinoculating Rhizobium leguminosarum bv. viciae 128C53 and Bacillus simplex 30N-5 onto Pisum sativum L. roots resulted in better nodulation and increased plant growth.The exact mechanisms whereby coinoculation results in increased plant growth are incompletely understood, but the synthesis of phytohormones and siderophores, the improved solubilization of inorganic nutrients, and the production of antimicrobial compounds are likely possibilities.Because B. simplex 30N-5 is not widely recognized as a Plant Growth Promoting Bacterial (PGPB) species, after sequencing its genome, we searched for genes proposed to promote plant growth, and then compared these sequences with those from several well studied PGPB species.

View Article: PubMed Central - PubMed

Affiliation: Departments of Molecular, Cell, and Developmental Biology, University of California, Los Angeles Los Angeles, CA, USA.

ABSTRACT
In previous work, we showed that coinoculating Rhizobium leguminosarum bv. viciae 128C53 and Bacillus simplex 30N-5 onto Pisum sativum L. roots resulted in better nodulation and increased plant growth. We now expand this research to include another alpha-rhizobial species as well as a beta-rhizobium, Burkholderia tuberum STM678. We first determined whether the rhizobia were compatible with B. simplex 30N-5 by cross-streaking experiments, and then Medicago truncatula and Melilotus alba were coinoculated with B. simplex 30N-5 and Sinorhizobium (Ensifer) meliloti to determine the effects on plant growth. Similarly, B. simplex 30N-5 and Bu. tuberum STM678 were coinoculated onto Macroptilium atropurpureum. The exact mechanisms whereby coinoculation results in increased plant growth are incompletely understood, but the synthesis of phytohormones and siderophores, the improved solubilization of inorganic nutrients, and the production of antimicrobial compounds are likely possibilities. Because B. simplex 30N-5 is not widely recognized as a Plant Growth Promoting Bacterial (PGPB) species, after sequencing its genome, we searched for genes proposed to promote plant growth, and then compared these sequences with those from several well studied PGPB species. In addition to genes involved in phytohormone synthesis, we detected genes important for the production of volatiles, polyamines, and antimicrobial peptides as well as genes for such plant growth-promoting traits as phosphate solubilization and siderophore production. Experimental evidence is presented to show that some of these traits, such as polyamine synthesis, are functional in B. simplex 30N-5, whereas others, e.g., auxin production, are not.

No MeSH data available.


Biomass measurements of Melilotus alba and Macroptilium atropurpureum 35 days post inoculation. (A)Melilotus alba plants were singly or coinoculated with Bacilus simplex (B.s.) and Sinorhizobium meliloti (S.m.); Different letters represent values that differ significantly, p < 0.01. (B) Jittered boxplot. Macroptilium atropurpureum plants were singly or coinoculated with Bacillus simplex (B.s.) and Burkholderia tuberum (B.t). The first coinoculation (1) introduced both bacteria species at the same time, whereas the second (2) was inoculated with B.s. first followed by B.t. inoculation 5 days later. Harvesting was performed as described in Methods. Boxes indicate minimum, maximum, 1st and 3rd quartiles and the median value.
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Figure 3: Biomass measurements of Melilotus alba and Macroptilium atropurpureum 35 days post inoculation. (A)Melilotus alba plants were singly or coinoculated with Bacilus simplex (B.s.) and Sinorhizobium meliloti (S.m.); Different letters represent values that differ significantly, p < 0.01. (B) Jittered boxplot. Macroptilium atropurpureum plants were singly or coinoculated with Bacillus simplex (B.s.) and Burkholderia tuberum (B.t). The first coinoculation (1) introduced both bacteria species at the same time, whereas the second (2) was inoculated with B.s. first followed by B.t. inoculation 5 days later. Harvesting was performed as described in Methods. Boxes indicate minimum, maximum, 1st and 3rd quartiles and the median value.

Mentions: Because B. simplex 30N-5 demonstrated a positive effect on both plant growth and rhizobial nodulation on pea (Schwartz et al., 2013), we tested whether or not this was a general phenomenon by coinoculating B. simplex 30N-5 and S. meliloti Rm1021 onto roots of M. truncatula and M. alba. In contrast to our previous results with pea, M. alba exhibited no significant growth enhancement when inoculated with B. simplex alone over the uninoculated control (Figure 3A). Although shoot height and nodule number were measured for all the conditions examined, no statistical significance was observed when the experimental treatments were compared with their respected controls (data not shown). Moreover, when single inoculations with S. meliloti and coinoculations with both strains were compared, the treatments (measured as dry weight increase) did not differ from each other although both were statistically different from the uninoculated and B. simplex alone-inoculated plants (Figure 3A). M. truncatula exhibited a similar response (data not shown). Overall, we found that dry weight increases were a more reliable measurement of plant biomass accumulation than any other parameters (see next section).


Mining the phytomicrobiome to understand how bacterial coinoculations enhance plant growth.

Maymon M, Martínez-Hidalgo P, Tran SS, Ice T, Craemer K, Anbarchian T, Sung T, Hwang LH, Chou M, Fujishige NA, Villella W, Ventosa J, Sikorski J, Sanders ER, Faull KF, Hirsch AM - Front Plant Sci (2015)

Biomass measurements of Melilotus alba and Macroptilium atropurpureum 35 days post inoculation. (A)Melilotus alba plants were singly or coinoculated with Bacilus simplex (B.s.) and Sinorhizobium meliloti (S.m.); Different letters represent values that differ significantly, p < 0.01. (B) Jittered boxplot. Macroptilium atropurpureum plants were singly or coinoculated with Bacillus simplex (B.s.) and Burkholderia tuberum (B.t). The first coinoculation (1) introduced both bacteria species at the same time, whereas the second (2) was inoculated with B.s. first followed by B.t. inoculation 5 days later. Harvesting was performed as described in Methods. Boxes indicate minimum, maximum, 1st and 3rd quartiles and the median value.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4585168&req=5

Figure 3: Biomass measurements of Melilotus alba and Macroptilium atropurpureum 35 days post inoculation. (A)Melilotus alba plants were singly or coinoculated with Bacilus simplex (B.s.) and Sinorhizobium meliloti (S.m.); Different letters represent values that differ significantly, p < 0.01. (B) Jittered boxplot. Macroptilium atropurpureum plants were singly or coinoculated with Bacillus simplex (B.s.) and Burkholderia tuberum (B.t). The first coinoculation (1) introduced both bacteria species at the same time, whereas the second (2) was inoculated with B.s. first followed by B.t. inoculation 5 days later. Harvesting was performed as described in Methods. Boxes indicate minimum, maximum, 1st and 3rd quartiles and the median value.
Mentions: Because B. simplex 30N-5 demonstrated a positive effect on both plant growth and rhizobial nodulation on pea (Schwartz et al., 2013), we tested whether or not this was a general phenomenon by coinoculating B. simplex 30N-5 and S. meliloti Rm1021 onto roots of M. truncatula and M. alba. In contrast to our previous results with pea, M. alba exhibited no significant growth enhancement when inoculated with B. simplex alone over the uninoculated control (Figure 3A). Although shoot height and nodule number were measured for all the conditions examined, no statistical significance was observed when the experimental treatments were compared with their respected controls (data not shown). Moreover, when single inoculations with S. meliloti and coinoculations with both strains were compared, the treatments (measured as dry weight increase) did not differ from each other although both were statistically different from the uninoculated and B. simplex alone-inoculated plants (Figure 3A). M. truncatula exhibited a similar response (data not shown). Overall, we found that dry weight increases were a more reliable measurement of plant biomass accumulation than any other parameters (see next section).

Bottom Line: In previous work, we showed that coinoculating Rhizobium leguminosarum bv. viciae 128C53 and Bacillus simplex 30N-5 onto Pisum sativum L. roots resulted in better nodulation and increased plant growth.The exact mechanisms whereby coinoculation results in increased plant growth are incompletely understood, but the synthesis of phytohormones and siderophores, the improved solubilization of inorganic nutrients, and the production of antimicrobial compounds are likely possibilities.Because B. simplex 30N-5 is not widely recognized as a Plant Growth Promoting Bacterial (PGPB) species, after sequencing its genome, we searched for genes proposed to promote plant growth, and then compared these sequences with those from several well studied PGPB species.

View Article: PubMed Central - PubMed

Affiliation: Departments of Molecular, Cell, and Developmental Biology, University of California, Los Angeles Los Angeles, CA, USA.

ABSTRACT
In previous work, we showed that coinoculating Rhizobium leguminosarum bv. viciae 128C53 and Bacillus simplex 30N-5 onto Pisum sativum L. roots resulted in better nodulation and increased plant growth. We now expand this research to include another alpha-rhizobial species as well as a beta-rhizobium, Burkholderia tuberum STM678. We first determined whether the rhizobia were compatible with B. simplex 30N-5 by cross-streaking experiments, and then Medicago truncatula and Melilotus alba were coinoculated with B. simplex 30N-5 and Sinorhizobium (Ensifer) meliloti to determine the effects on plant growth. Similarly, B. simplex 30N-5 and Bu. tuberum STM678 were coinoculated onto Macroptilium atropurpureum. The exact mechanisms whereby coinoculation results in increased plant growth are incompletely understood, but the synthesis of phytohormones and siderophores, the improved solubilization of inorganic nutrients, and the production of antimicrobial compounds are likely possibilities. Because B. simplex 30N-5 is not widely recognized as a Plant Growth Promoting Bacterial (PGPB) species, after sequencing its genome, we searched for genes proposed to promote plant growth, and then compared these sequences with those from several well studied PGPB species. In addition to genes involved in phytohormone synthesis, we detected genes important for the production of volatiles, polyamines, and antimicrobial peptides as well as genes for such plant growth-promoting traits as phosphate solubilization and siderophore production. Experimental evidence is presented to show that some of these traits, such as polyamine synthesis, are functional in B. simplex 30N-5, whereas others, e.g., auxin production, are not.

No MeSH data available.