Allelopathy and Self-Defense in Barley

Lovett, J. V.; Hoult, A. H. C.

doi:10.1021/bk-1995-0582.ch013

Cited by 38 publications

(26 citation statements)

References 24 publications

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“…Others have found dual antiherbivore-allelopathic roles in inducible plant metabolites (Lovett and Holt 1995), and increased allelopathic productivity under stress (Tang et al 1995). Others have found dual antiherbivore-allelopathic roles in inducible plant metabolites (Lovett and Holt 1995), and increased allelopathic productivity under stress (Tang et al 1995).…”

Section: Discussionmentioning

confidence: 99%

Biological-Control Herbivores May Increase Competitive Ability of the Noxious Weed Centaurea maculosa

Callaway¹,

DeLuca²,

Belliveau³

1999

Ecology

110

117

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Biocontrol organisms are generally applied in an attempt to reduce the vigor of target species and provide native species with an competitive advantage. We tested the effectiveness of a widely used biocontrol moth, Agapeta zoegana (knapweed root moth) for two years in the field and found that it had no significant direct effect on the biomass of Centaurea maculosa (spotted knapweed), one of the most destructive invasive plants in North America. Instead of releasing a native grass from competition, the reproductive output of Festuca idahoensis planted with Centaurea was significantly lower when neighboring Centaurea had been attacked by Agapeta. In a greenhouse experiment, we found that Festuca planted in pots with Centaurea that had been attacked by Trichoplusia ni (another nonnative herbivore) had significantly smaller root systems than when they were planted with Centaurea that were protected from herbivory. Root systems of Centaurea that had been attacked by Trichoplusia exuded higher levels of total sugars, but not total phenols. We hypothesize that moderate herbivory stimulated compensatory growth, induced the production of defense chemicals that also had allelopathic effects, or stimulated root exudates that altered the relationship between Centaurea and Festuca via soil microbes. Our data suggest that herbivory may increase the negative effects of C. maculosa on neighboring plants, and that some biocontrols may have indirect negative effects on native species that are not currently recognized.

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Section: Discussionmentioning

confidence: 99%

Biological-Control Herbivores May Increase Competitive Ability of the Noxious Weed Centaurea maculosa

Callaway¹,

DeLuca²,

Belliveau³

1999

Ecology

110

117

View full text Add to dashboard Cite

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“…Artificial mixtures of gramine and hordenine at levels quantified in root exudates are phytotoxic, suggesting that these alkaloids play a role in allelopathy of barley. Selection for agronomic traits in barley appears to have unintentionally favoured hordenine biosynthesis, whereas the ability to synthesize gramine seems to be reduced or even lost in modern cultivars, just as observed for benzoxazinoid biosynthesis in cultivated barley 57, 77…”

Section: Crop Allelopathy—a Short Historymentioning

confidence: 94%

Allelopathy in crop/weed interactions — an update

Belz

2006

Pest Management Science

278

277

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Since varietal differences in allelopathy of crops against weeds were discovered in the 1970s, much research has documented the potential that allelopathic crops offer for integrated weed management with substantially reduced herbicide rates. Research groups worldwide have identified several crop species possessing potent allelopathic interference mediated by root exudation of allelochemicals. Rice, wheat, barley and sorghum have attracted most attention. Past research focused on germplasm screening for elite allelopathic cultivars and the identification of the allelochemicals involved. Based on this, traditional breeding efforts were initiated in rice and wheat to breed agronomically acceptable, weed-suppressive cultivars with improved allelopathic interference. Promising suppressive crosses are under investigation. Molecular approaches have elucidated the genetics of allelopathy by QTL mapping which associated the trait in rice and wheat with several chromosomes and suggested the involvement of several allelochemicals. Potentially important compounds that are constitutively secreted from roots have been identified in all crop species under investigation. Biosynthesis and exudation of these metabolites follow a distinct temporal pattern and can be induced by biotic and abiotic factors. The current state of knowledge suggests that allelopathy involves fluctuating mixtures of allelochemicals and their metabolites as regulated by genotype and developmental stage of the producing plant, environment, cultivation and signalling effects, as well as the chemical or microbial turnover of compounds in the rhizosphere. Functional genomics is being applied to identify genes involved in biosynthesis of several identified allelochemicals, providing the potential to improve allelopathy by molecular breeding. The dynamics of crop allelopathy, inducible processes and plant signalling is gaining growing attention; however, future research should also consider allelochemical release mechanisms, persistence, selectivity and modes of action, as well as consequences of improved crop allelopathy on plant physiology, the environment and management strategies. Creation of weed-suppressive cultivars with improved allelopathic interference is still a challenge, but traditional breeding or biotechnology should pave the way.

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“…In contrast, Cipollini (2002) found no effect of competition on costs of induced defenses in Arabadopsis, probably because plants experiencing competition did not increase their defenses to the same degree as did control plants. Others have found evidence for dual antiherbivore/allelopathic roles in inducible plant metabolites (Lovett and Hoult 1995, Tang et al 1995 found that exudation of some compounds from the roots of Centaurea maculosa increased after moderate leaf herbivory. They used artificial selection and herbivore-induction treatments to produce genetic and environmental variation in concentrations of the defense chemicals myrosinase and glucosinolate in different genetic lines of B. rapa.…”

Section: Plasticity In Response To Herbivorymentioning

confidence: 99%

Phenotypic Plasticity and Interactions Among Plants

Callaway

Pennings

Richards

2003

Ecology

646

394

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We know a great deal about the plastic responses of plant phenotypes to the abiotic and biotic environment, but very little about the consequences of phenotypic plasticity for plant communities. In other words, we know that plant traits can vary widely for a given genotype, but we know little about the importance of trait-mediated interactions (TMI) among plants. Here, we discuss three major factors that affect the expression of phenotypic plasticity: variation in the abiotic environment, variation in the presence or identity of neighbors, and variation in herbivory. We consider how plastic responses to these factors might affect interactions among plants. Plastic responses to the abiotic environment have important consequences for conditionality in competitive effects, to the point of causing shifts from competitive to facilitative interactions. Because plants show a high degree of plasticity in response to neighbors, and even to the specific identify of neighbors, phenotypic plasticity may allow species to adjust to the composition of their communities, promoting coexistence and community diversity. Likewise, plastic responses to consumers may have various and counterintuitive consequences: induction of plant resistance, compensatory growth, and increased resource uptake may affect interactions among plants in ways that cannot be predicted simply by considering biomass lost to consumers. What little we know about TMI among plants suggests that they should not be ignored in plant community theory. Although work to date on the community consequences of phenotypic plasticity has been hampered by experimental constraints, new approaches such as manipulating phenotypes by using signals instead of actual environmental conditions and the use of transgenic plants should allow us to rapidly expand our understanding of the community consequences of plant plasticity.

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Allelopathy and Self-Defense in Barley

Cited by 38 publications

References 24 publications

Biological-Control Herbivores May Increase Competitive Ability of the Noxious Weed Centaurea maculosa

Biological-Control Herbivores May Increase Competitive Ability of the Noxious Weed Centaurea maculosa

Allelopathy in crop/weed interactions — an update

Phenotypic Plasticity and Interactions Among Plants

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