Cyanide in the Chemical Arsenal of Garlic Mustard, Alliaria petiolata

Department of Biological Sciences, Wright State University, Dayton, Ohio, United States
Journal of Chemical Ecology (Impact Factor: 2.75). 02/2007; 33(1):85-94. DOI: 10.1007/s10886-006-9205-x
Source: PubMed


Cyanide production has been reported from over 2500 plant species, including some members of the Brassicaceae. We report that the important invasive plant, Alliaria petiolata, produces levels of cyanide in its tissues that can reach 100 ppm fresh weight (FW), a level considered toxic to many vertebrates. In a comparative study, levels of cyanide in leaves of young first-year plants were 25 times higher than in leaves of young Arabidopsis thaliana plants and over 150 times higher than in leaves of young Brassica kaber, B. rapa, and B. napus. In first-year plants, cyanide levels were highest in young leaves of seedlings and declined with leaf age on individual plants. Leaves of young plants infested with green peach aphids (Myzus persicae) produced just over half as much cyanide as leaves of healthy plants, suggesting that aphid feeding led to loss of cyanide from intact tissues before analysis, or that aphid feeding inhibited cyanide precursor production. In a developmental study, levels of cyanide in the youngest and oldest leaf of young garlic mustard plants were four times lower than in the youngest and oldest leaf of young Sorghum sudanense (cv. Cadan 97) plants, but cyanide levels did not decline in these leaves with plant age as in S. sudanense. Different populations of garlic mustard varied moderately in the constitutive and inducible expression of cyanide in leaves, but no populations studied were acyanogenic. Although cyanide production could result from breakdown products of glucosinolates, no cyanide was detected in vitro from decomposition of sinigrin, the major glucosinolate of garlic mustard. These studies indicate that cyanide produced from an as yet unidentified cyanogenic compound is a part of the battery of chemical defenses expressed by garlic mustard.

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    • "Both alliarinoside and sinigrin tend to be concentrated in new leaves, and alliarinoside peaks during mid­summer in rosette leaves (Frisch et al. 2014 ; Haribal and Renwick 2001 ). Finally, A. petiolata is unique in its production of other compounds that may be involved in insect resistance, such as cyanide (Cipollini and Gruner 2007 ). Davis and Cipollini ( 2014 ) "
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    ABSTRACT: As it pertains to insect herbivores, the preference-performance hypothesis posits that females will choose oviposition sites that maximize their offspring's fitness. However, both genetic and environmental cues contribute to oviposition preference, and occasionally "oviposition mistakes" occur, where insects oviposit on hosts unsuitable for larval development. Pieris virginiensis is a pierine butterfly native to North America that regularly oviposits on an invasive plant, Alliaria petiolata, but the caterpillars are unable to survive. Alliaria petiolata has high concentrations of the glucosinolate sinigrin in its tissues, as well as a hydroxynitrile glucoside, alliarinoside. We investigated sinigrin as a possible cause of mistake oviposition, and sinigrin and alliarinoside as possible causes of larval mortality. We found that sinigrin applied to leaves of Cardamine diphylla, a major host of P. virginiensis that does not produce sinigrin, had no effect on oviposition rates. We tested the effect of sinigrin on larval performance using two host plants, one lacking sinigrin (C. diphylla) and one with sinigrin naturally present (Brassica juncea). We found no effect of sinigrin application on survival of caterpillars fed C. diphylla, but sinigrin delayed pupation and decreased pupal weight. On B. juncea, sinigrin decreased survival, consumption, and caterpillar growth. We also tested the response of P. virginiensis caterpillars to alliarinoside, a compound unique to A. petiolata, which was applied to B. oleracea. We found a significant reduction in survival, leaf consumption, and caterpillar size when alliarinoside was consumed. The 'novel weapon' alliarinoside likely is largely responsible for larval failure on the novel host A. petiolata. Sinigrin most likely contributes to the larval mortality observed, however, we did not observe any effect of sinigrin on oviposition by P. virginiensis females. Further research needs to be done on non-glucosinolate contact cues, and volatile signals that may induce P. virginiensis oviposition.
    Journal of Chemical Ecology 09/2015; 41(10). DOI:10.1007/s10886-015-0633-3 · 2.75 Impact Factor
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    • "While it exists in small populations throughout its native range (Blossey et al. 2001), in its invasive range A. petiolata spreads quickly and can form persistent, dense stands (Nuzzo 1999; Rodgers et al. 2008a) and reduces native biodiversity (Anderson et al. 1996; McCarthy 1997; Lankau et al. 2009). A. petiolata produces allelopathic chemicals that harm native plants and soil biota (Cipollini and Gruner 2007; Callaway et al. 2008). Two of its most studied allelochemicals are allyl isothiocyanate (AITC) and benzyl isothiocyanate (BITC) (Vaughn and Berhow 1999). "
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    ABSTRACT: Some introduced species become invasive by releasing novel allelochemicals into the soil, directly harming nearby plants and soil microbes. Alliaria petiolata (garlic mustard) is an invasive plant, well known to excrete a suite of phytotoxic and anti-microbial allelochemicals, including allyl isothio-cyanate (AITC) and benzyl isothiocyanate (BITC). While the effects of these chemicals on plant-mycor-rhizae mutualisms are well documented, the effects on other plant-soil microbe interactions, such as the legume-rhizobia mutualism, have not yet been tested. Here, we performed laboratory and greenhouse experiments with both synthetic chemicals and leaf extracts to investigate the effects of allelochemicals in A. petiolata on a native leguminous plant, Amphicarpaea bracteata, and its rhizobia mutualists. We found that BITC reduced rhizobia growth rate in the lab, but had no effect on nodulation in the greenhouse when rhizobia were grown in the presence of plants. AITC did not directly harm either plants or rhizobia, though plants and rhizobia grown in the presence of AITC showed reduced nodulation, indicating that it disrupted the formation of the mutualism itself. We found no effects of A. petiolata allelochemical leaf extracts on plant performance or nodulation. Our data suggest that AITC causes mutualism disruption in this system by preventing the formation of nodules, which reduces plant growth and could threaten the long-term performance of rhizobia. Our study shows that the allelo-chemicals in A. petiolata disrupt the legume-rhizobia resource mutualism, adding another impact of these novel weapons in addition to their well-documented role in disrupting plant-mycorrhizae symbioses.
    Biological Invasions 09/2015; 17(9):2779-2791. DOI:10.1007/s10530-015-0913-4 · 2.59 Impact Factor
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    • "The European biennial garlic mustard (Alliaria petiolata) is one of the most invasive and abundant non-native plants in the forests of southern Wisconsin (Rogers et al., 2008). Garlic mustard reduces native plant germination, growth, and diversity by releasing secondary compounds (allelopathy) that diminish and disrupt mycorrhizal associations, altering soil chemistry, and outcompeting natives for space and resources (Rodgers et al., 2008; Meekins and McCarthy, 1999; Stinson et al. 2006; Roberts and Anderson, 2001; Prati and Bossdorf, 2004; Murphy 2005; Barto et al., 2010; Cipollini and Gruner, 2007; Stinson et al., 2006; Wolfe et al., 2008; Wixted and McGraw, 2010; Lankau, 2011). Deer could accentuate these impacts to native plants via ''apparent competition'' if deer and other herbivores avoid Alliaria to feed preferentially on native species. "
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    ABSTRACT: Herbivores and invasive plants strongly affect the persistence of individual species and the overall com- position of forest plant communities. Although their impacts are usually studied separately, they often co-occur with potential synergistic effects on native plants. We used a 2 􏰁 2 experimental design repli- cated across five locations in southern Wisconsin to assess the separate and combined effects of herbiv- ory by white-tailed deer (Odocoileus virginianus) and competition from the weedy invader Alliaria petiolata (garlic mustard) on five native species. Deer and Alliaria often reduce the growth and survival of native plants in these forests. A fenced exclosure erected at each site surrounded one of two pairs of adjacent plots densely occupied by Alliaria. We cleared one plot (in- and outside each exclosure) of Alliaria and then planted seedlings of the native species into all four plots. Species were chosen to display differ- ent functional traits (Aster lateriflorus/Symphyotrichum lateriflorum, Carex blanda, Geranium maculatum, Quercus rubra, and Uvularia grandiflora). We then monitored native seedling growth and survival for 13 months. Deer access depressed survival and branching in Uvularia, growth in Geranium and Quercus, and tillering in Carex. The presence of Alliaria reduced height and tillering in Carex and Geranium but increased branching, reproduction, and survival in Uvularia. Thus, Alliaria may sometimes act to protect taxa like Uvularia sensitive to deer herbivory. Alliaria reduced the growth of Carex, Geranium, and Quercus significantly more in the absence of deer. Such interactive effects suggest that when deer do not restrict growth, plants grow larger to a point where Alliaria’s competitive effects increase. The impacts of both deer and Alliaria varied by species and trait. Species experiencing regional declines (e.g., oak seedlings and the lily, Uvularia) were more affected by deer than by Alliaria. Oak seedlings suffer particularly from Alliaria competition when deer are absent. Managers seeking to sustain deer-sensitive species should first work to reduce deer densities before seeking to control weedy plant invasions. Alliaria reduced growth more in species that tolerate deer browsing (Carex and Geranium). These differential responses argue for tailoring local deer and weedy plant control efforts to the taxa of concern. Deer and weedy plants have cumulative effects on native plant species. Interactions between their effects will become more impor- tant as their populations and impacts increase. 
    Forest Ecology and Management 06/2013; 304:296-302. DOI:10.1016/j.foreco.2013.05.011 · 2.66 Impact Factor
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