22 research outputs found

    Defensive properties of pyrrolizidine alkaloids against microorganisms

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    The understanding of the selection factors that drive chemical diversification of secondary metabolites of constitutive defence systems in plants, such as pyrrolizidine alkaloids (PAs), is still incomplete. Historically, plants always have been confronted with microorganisms. Long before herbivores existed on this planet, plants had to cope with microbial pathogens. Therefore, plant pathogenic microorganisms may have played an important role in the early evolution of the secondary metabolite diversity. In this review, we discuss the impact that plant-produced PAs have on plant-associated microorganisms. The objective of the review is to present the current knowledge on PAs with respect to anti-microbial activities, adaptation and detoxification by microorganisms, pathogenic fungi, root protection and PA induction. Many in vitro experiments showed effects of PAs on microorganisms. These results point to the potential of microorganisms to be important for the evolution of PAs. However, only a few in vivo studies have been published and support the results of the in vitro studies. In conclusion, the topics pointed out in this review need further exploration by carrying out ecological experiments and field studies

    The "People" Factor in Cooperatives: An Analysis of Members' Attitudes and Behavior

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    "Members' attitudes and perceptions play a significant role in their behavior toward their organization and the performance of such organizations. This study examines the role of these "people" factors in a sample of fruit and vegetable growers' cooperatives in the Mid-Atlantic United States. Although the Theory of Planned Behavior is used as the framework of analysis, the objective of this study was not to test the theory. Study findings provide additional insights into how cooperative members' beliefs and knowledge may shape their attitudes and the consequent behavior. Given the gradual decline of both cooperative memberships and the number of cooperatives in the United States and other countries, a good understanding of members' attitudes and behaviors is necessary because a cooperative's success may depend on it." Copyright 2007 Canadian Agricultural Economics Society.
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