Dataset Information

Defensive Traits in Young Pine Trees Cluster into Two Divergent Syndromes Related to Early Growth Rate.

ABSTRACT: The combination of defensive traits leads to the evolution of 'plant defense syndromes' which should provide better protection against herbivores than individual traits on their own. Defense syndromes can be generally driven by plant phylogeny and/or biotic and abiotic factors. However, we lack a solid understanding of (i) the relative importance of shared evolution vs. convergence due to similar ecological conditions and (ii) the role of induced defense strategies in shaping defense syndromes. We investigate the relative roles of evolutionary and ecological factors shaping the deployment of pine defense syndromes including multiple constitutive and induced chemical defense traits. We performed a greenhouse experiment with seedlings of eighteen species of Pinaceae family, and measured plant growth rate, constitutive chemical defenses and their inducibility. Plant growth rate, but not phylogenetic relatedness, determined the deployment of two divergent syndromes. Slow-growing pine species living in harsh environments where tissue replacement is costly allocated more to constitutive defenses (energetically more costly to produce than induced). In contrast, fast-growing species living in resource-rich habitats had greater inducibility of their defenses, consistent with the theory of constitutive-induced defense trade-offs. This study contributes to a better understanding of evolutionary and ecological factors driving the deployment of defense syndromes.

SUBMITTER: Moreira X

PROVIDER: S-EPMC4814073 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Defensive Traits in Young Pine Trees Cluster into Two Divergent Syndromes Related to Early Growth Rate.

Moreira Xoaquín X Sampedro Luis L Zas Rafael R Pearse Ian S IS

PloS one 20160330 3

The combination of defensive traits leads to the evolution of 'plant defense syndromes' which should provide better protection against herbivores than individual traits on their own. Defense syndromes can be generally driven by plant phylogeny and/or biotic and abiotic factors. However, we lack a solid understanding of (i) the relative importance of shared evolution vs. convergence due to similar ecological conditions and (ii) the role of induced defense strategies in shaping defense syndromes. ...[more]

PMID: 27028433

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Project description:Plant growth rates drive ecosystem productivity and are a central element of plant ecological strategies. For seedlings grown under controlled conditions, a large literature has firmly identified the functional traits that drive interspecific variation in growth rate. For adult plants, the corresponding knowledge is surprisingly poorly understood. Until recently it was widely assumed that the key trait drivers would be the same (e.g. specific leaf area, or SLA), but an increasing number of papers has demonstrated this not to be the case, or not generally so. New theory has provided a prospective basis for understanding these discrepancies. Here we quantified relationships between stem diameter growth rates and functional traits of adult woody plants for 41 species in an Australian tropical rainforest. From various cost-benefit considerations, core predictions included that: (i) photosynthetic rate would be positively related to growth rate; (ii) SLA would be unrelated to growth rate (unlike in seedlings where it is positively related to growth); (iii) wood density would be negatively related to growth rate; and (iv) leaf mass:sapwood mass ratio (LM:SM) in branches (analogous to a benefit:cost ratio) would be positively related to growth rate. All our predictions found support, particularly those for LM:SM and wood density; photosynthetic rate was more weakly related to stem diameter growth rates. Specific leaf area was convincingly correlated to growth rate, in fact negatively. Together, SLA, wood density and LM:SM accounted for 52 % of variation in growth rate among these 41 species, with each trait contributing roughly similar explanatory power. That low SLA species can achieve faster growth rates than high SLA species was an unexpected result but, as it turns out, not without precedent, and easily understood via cost-benefit theory that considers whole-plant allocation to different tissue types. Branch-scale leaf:sapwood ratio holds promise as an easily measurable variable that may help to understand growth rate variation. Using cost-benefit approaches teamed with combinations of leaf, wood and allometric variables may provide a path towards a more complete understanding of growth rates under field conditions.

Project description:BackgroundThere is growing evidence that some devastating biotic invasions are facilitated by microbial symbionts. The red turpentine beetle (RTB), an innocuous secondary insect attacking weakened trees in North America, has formed an invasive complex with the fungus Leptographium procerum in China, and this invasive beetle-fungus symbiotic complex is capable of attacking and killing healthy pines. A previous study demonstrated that three Chinese-resident fungi, newly acquired by RTB in China, induce high levels of a phenolic defensive chemical, naringenin, in pines and this invasive beetle-fungus complex is suppressed by elevated levels of naringenin while the beetle uses its gallery as an external detoxification system in which particular yeast-like fungi and bacterial species biodegrade naringenin. However, the functional roles of key microbial players in the symbiosis, contained within the microbiome of the bark beetle gallery, have not been well elucidated.ResultsIn this report, the symbiotic naringenin-degrading microbiota were found to increase RTB survivorship in the presence of induced host defenses, and potential genes associated with degradation pathways were discovered. While fungi in the gallery microbiota had little involvement in naringenin degradation, bacterial community structure within the beetle gallery was highly correlated to naringenin degrading activity. Phylotypes of the Gram-negative bacterial genus Novosphingobium, which possessed genes involved in degradation pathways, were highly correlated to naringenin degradation activities and RTB associated with an isolated species of this genus acquired protection against naringenin and gained fitness.ConclusionsOur results demonstrated that symbiotic bacterial community of RTB galleries enhances the survivorship and overall fitness of invasive beetles by degrading the host phenolic naringenin, ultimately overcoming the tree defenses and facilitating the success of the invasive beetle-fungi complex. This dynamic interplay between the invasive insect pest and multipartite microbes suggests a putative mechanism in invasion ecology for mitigating biotic resistance to symbiotic invasion.

Project description:Bacteria in the genus Pantoea (family Enterobacteriales) are metabolically diverse, cosmopolitan, and form a wide range of interactions with eukaryotic hosts including plants, fungi, insects and humans. Several Pantoea species have pathogenic interactions with plants. Strains of at least four Pantoea species (P. ananatis, P. allii, P. stewartii subsp. indologenes and P. agglomerans) are known to cause onion center rot disease. P. ananatis is very unusual among characterized bacterial plant pathogens. Virulence factors that distinguish onion-virulent and non-virulent P. ananatis have only recently been described. Most bacterial plant pathogens are dependent on specialized virulence protein secretion systems for pathogenicity. However, to cause plant cell death, P. ananatis instead requires the HiVir (High Virulence) proposed secondary metabolite synthetic cluster for an as of yet undescribed phosphonate compound. P. allii is also pathogenic on onion but, surprisingly, lacks the HiVir gene cluster associated with onion-virulent P. ananatis. P. allii carries a completely distinct predicted phosphonate compound synthetic cluster which has, interestingly, also been identified in P. stewartiii subsp indologenes that have expanded their host range from millet onto onions. We obtained the cell pellet metabolite profiles of P. ananatis PNA 97-1, the P. allii type strain LMG 24248, and the two corresponding biosynthetic mutant strains lacking a key gene (pepM) for the synthesis of phosphonate compounds. Understanding the unique chemistry of onion-virulent Pantoea will yield important insights into novel frameworks for plant- pathogen interactions. The work (proposal:https://doi.org/10.46936/10.25585/60001193) conducted by the U.S. Department of Energy Joint Genome Institute (https://ror.org/04xm1d337), a DOE Office of Science User Facility, is supported by the Office of Science of the U.S. Department of Energy operated under Contract No. DE-AC02-05CH11231.

Dataset Information

Defensive Traits in Young Pine Trees Cluster into Two Divergent Syndromes Related to Early Growth Rate.

Publications

Defensive Traits in Young Pine Trees Cluster into Two Divergent Syndromes Related to Early Growth Rate.

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