Benzoxazinoids (BXs) are secondary metabolites present in many Poaceae including the major crops maize, wheat, and rye. In contrast to other potentially toxic secondary metabolites, BXs have not been targets of counter selection during breeding and the effect of BXs on insects, microbes, and neighbouring plants has been recognised. A broad knowledge about the mode of action and metabolisation in target organisms including herbivorous insects, aphids, and plants has been gathered in the last decades. BX biosynthesis has been elucidated on a molecular level in crop cereals. Recent advances, mainly made by investigations in maize, uncovered a significant diversity in the composition of BXs within one species. The pattern can be specific for single plant lines and dynamic changes triggered by biotic and abiotic stresses were observed. Single BXs might be toxic, repelling, attractive, and even growth-promoting for insects, depending on the particular species. BXs delivered into the soil influence plant and microbial communities. Furthermore, BXs can possibly be used as signalling molecules within the plant. In this review we intend to give an overview of the current data on the biosynthesis, structure, and function of BXs, beyond their characterisation as mere phytotoxins.2 of 24 by the producing plant. In the so-called two-component defence systems, reactivity is reduced by chemical modification, mostly glycosylation, and simultaneously a reactivating enzyme, e.g., a glycosidase, is provided. The stabilised metabolite (component one) and activating enzyme (component two) are physically separated in different organelles or tissues but meet in case of cell damage, thereby liberating the toxin. Examples are alkaloid glucosides, benzoxazinoid glucosides, cyanogenic glucosides, glucosinolates, iridoid glucosides, and salicinoids (see [7] for review).Advances in chemical analysis and well-developed genetic resources, especially in maize, have revealed distinct functions for different BXs in defence. Furthermore, in planta signalling is a matter of debate [8]. Within maize populations, diversity in the quality and quantity of different BXs has been revealed. Recent reviews summarise the role of BXs on plant-plant allelopathy [9], deal with the interaction between BXs and insects [10], and describe the BX structure diversity and function in maize [8]. Here we aim to give an overview on the present knowledge of the biosynthesis, distribution, and biological function of different BXs. The available data on BX-mediated interactions are summarised in Table 1, providing a guide through the literature.

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Aim Extreme heat events caused by climate change continue to increase in frequency, duration, and intensity. People living in cities in particular are exposed to heat as a result of the urban heat island effect. Although negative effects can be mitigated by heat health action plans (HHAPs), it remains unknown how many German cities have implemented such plans or other measures to reduce the health risks from heat. Therefore, this study surveyed the status of planned or published HHAPs and measures in German cities. Subject and methods Approximately 10% of German cities with the greatest population density were sampled for the study (n = 70 cities). A frequency analysis of city concepts and city webpages was conducted to determine whether cities have already introduced concepts for climate adaptation, climate protection or an HHAP, and which measures are planned in detail. Results Fifty-one cities have implemented measures to protect health from heat events. Forty-one cities integrated such measures into concepts, and only one city formulated an HHAP. Large cities in particular published measures. Long-term measures proved most common, for example, improved building envelope insulation and urban greening. Other than advice on individual behavior, hardly any acute heat health measures are being taken. Conclusion Public health authorities can play an active role in communicating the health risks of heat and implementing HHAPs. To this end, the health risks of climate change need to be addressed consistently by all policy fields in Germany. There is also a need for further research in the evaluation of measures and HHAPs.