Glucosinolates, a class of secondary metabolites, mainly found in Brassicaceae, are affected by the changing environment. This review is focusing on the physiological significance of glucosinolates and their hydrolysis products in the plant response to different abiotic stresses. Special attention is paid to the crosstalk between some of the physiological processes involved in stress response and glucosinolate metabolism, with the resulting connection between both pathways in which signaling mechanisms glucosinolate may act as signals themselves. The function of glucosinolates, further than in defense switching, is discussed in terms of alleviating pathogen attack under abiotic stress. The fact that the exogenous addition of glucosinolate hydrolysis products may alleviate certain stress conditions through its effect on specific proteins is described in light of the recent reports, but the molecular mechanisms involved in this response merit further research. Finally, the transient allocation and re-distribution of glucosinolates as a response to environmental changes is summarized.

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The physiological importance of glucosinolates on plant response to abiotic stress in Brassica.

The conventional understanding of the role of the seed coat is that it provides a protective layer for the developing zygote. Recent data show that the picture is more nuanced. The seed coat certainly represents a first line of defense against adverse external factors, but it also acts as channel for transmitting environmental cues to the interior of the seed. The latter function primes the seed to adjust its metabolism in response to changes in its external environment. The purpose of this review is to provide the reader with a comprehensive view of the structure and functionality of the seed coat, and to expose its hidden interaction with both the endosperm and embryo. Any breeding and/or biotechnology intervention seeking to increase seed size or modify seed features will have to consider the implications on this tripartite interaction.

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Physical, metabolic and developmental functions of the seed coat

Globally increasing temperatures may strongly affect insect herbivore performance, as their growth and development is directly linked to ambient temperature as well as host-plant quality. In contrast to direct effects of temperature on herbivores, indirect effects mediated via thermal effects on host-plant quality are only poorly understood, despite having the potential to substantially impact performance and thereby to alter responses to the changing climatic conditions. We here use a full-factorial design to explore the direct (larvae were reared at 17 °C or 25 °C) and indirect effects (host plants were reared at 17 °C or 25 °C) of temperature on larval growth and life-history traits in the temperate-zone butterfly Pieris napi. Direct temperature effects reflected the common pattern of prolonged development and increased body mass at lower temperatures. At the higher temperature, efficiency of converting food into body matter was much reduced being accompanied by an increased food intake, suggesting compensatory feeding. Indirect temperature effects were apparent as reduced body mass, longer development time, an increased food intake, and a reduced efficiency of converting food into body matter in larvae feeding on plants grown at the higher temperature, thus indicating poor host-plant quality. The effects of host-plant quality were more pronounced at the higher temperature, at which compensatory feeding was much less efficient. Our results highlight that temperature-mediated changes in host-plant quality are a significant, but largely overlooked source of variation in herbivore performance. Such effects may exaggerate negative effects of global warming, which should be considered when trying to forecast species' responses to climate change.

Increased temperature reduces herbivore host-plant quality.

White cabbage (Brassica oleraceae var. capitata f. alba) is a cruciferous vegetable used worldwide as a food and in traditional medicine. Due to its common availability in local markets, affordability, and consumer preference, it represents a significant source of phytonutrients in the human diet. This review provides an overview of white cabbage origin, taxonomy, geographical distribution, botanical characteristics, and contemporary and traditional uses, as well as its phytochemicals and pharmacology. Special emphasis is placed on a health-promoting phytochemicals such as glucosinolates, polyphenols, and vitamins, as well as anticancerogenic, antioxidant, anti-inflamantory and cardioprotective effects. The majority of so far published research on white cabbage was focused on qualitative determination of phytochemicals (targeted analysis), while only few recent papers published data based on untargeted metabolomic profiling. Hence, this review discusses and emphasizes a further need of studying the white cabbage phytochemicals using modern metabolomics platforms which will enable scientists to pinpoint the exact bioactive metabolites which are responsible for certain bioactivity.

White cabbage (Brassica oleracea var. capitata f. alba): botanical, phytochemical and pharmacological overview

Over-reliance on pesticides for pest control is inflicting serious damage to the environmental services that underpin agricultural productivity. The widespread use of systemic insecticides, neonicotinoids, and the phenylpyrazole fipronil in particular is assessed here in terms of their actual use in pest management, effects on crop yields, and the development of pest resistance to these compounds in many crops after two decades of usage. Resistance can only be overcome in the longterm by implementing methods that are not exclusively based on synthetic pesticides. A diverse range of pest management tactics is already available, all of which can achieve efficient pest control below the economic injury level while maintaining the productivity of the crops. A novel insurance method against crop failure is shown here as an example of alternative methods that can protect farmer’s crops and their livelihoods without having to use insecticides. Finally, some concluding remarks about the need for a new framework for a truly sustainable agriculture that relies mainly on natural ecosystem services instead of chemicals are included; this reinforcing the previous WIA conclusions (van der Sluijs et al. Environ Sci Pollut Res 22:148-154, 2015).

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An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 3: alternatives to systemic insecticides.

This review discusses the importance of glucosinolates in plant protection. The Brassicaceae, which are culti- vated worldwide, use glucosinolates and their decomposition products to defend themselves against attacks by harmful organisms. The glucosinolate content varies among individual plant species, plant organs and developmental stages. The glucosinolate content in plants is also affected by biotic and abiotic factors, while the type or quantity of glucosinolate de- termines the susceptibility of the plants to insect pests. These facts can pose a problem when implementing this knowledge in cultivation of the Brassicaceae, especially in regions with moderate climates where Brassicaceae crops are exposed to attacks by a large number of harmful organisms. Under these circumstances, it is essential to research new, or to improve the existing environmentally acceptable methods of protecting Brassicaceae plants against economically important pests.

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Glucosinolates in plant protection strategies: a review

Slovenia is a small country of Central Europe. Until recently, only limited surveys had been carried out of the Phytoseiidae fauna. The occurrence of 14 species had been documented in two international papers: 6 belonging to the subfamily Amblyseiinae, 1 to the subfamily Phytoseiinae and 7 to the subfamily Typhlodrominae. Four additional species (3 Amblyseiinae and 1 Phytoseiinae) were recorded and published recently but in a national journal and not mentioned in the world online database of Phytoseiidae. Here, we present results from 2018 and 2019 field surveys and add a total of 22 new records (18 if we consider national published records): 14 Amblyseiinae, 3 Phytoseiinae and 5 Typhlodrominae. The Phytoseiidae fauna of Slovenia contains after our study 36 species: 20 Amblyseiinae, 4 Phytoseiinae and 12 Typhlodrominae. Among the 22 new record species, at least 8 species are well-known biological control agents (BCA). In addition to the intrinsic value of phytoseiid mite biodiversity in temperate environments, demonstration of the natural occurrence of efficient BCAs is of great agricultural, commercial and strategic interests.

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Phytoseiid mites of Slovenia (Acari: Mesostigmata): new records and first description of the male of Amblyseius microorientalis

In 2009 and 2010, a field experiment was carried out to determine the effect of three trap crops (oil radish, oil rape and white mustard) as a protection method against cabbage stink bugs (Eurydema spp.) and flea beetles (Phyllotreta spp.) attack on two hybrids of white cabbage. The experiment was designed as randomized complete block with four treatments. The damage caused by cabbage stink bugs and flea beetles on the main crop and the trap crops was estimated in 10-day intervals. Oil rape was the most attractive trap crop for cabbage stink bugs, while flea beetles displayed specific preference to oil radish as a trap crop in 2010. Flea beetles displayed specific preference for oil radish as a trap crop in 2010, while they did not display specific preference to any of trap crops tested in 2009. The damage caused by cabbage stink bugs on cabbage started increasing in the beginning of July. The damage caused by flea beetles, on the other hand, started increasing at the end of May. Cabbage hybrid ‘Hinova’ was more heavily attacked by both groups of the pests, mostly due to its longer growth period. The extent of damage on cabbage and trap crops was higher in the second year, since before 2009 no Brassica crops were grown in the near vicinity of the experimental plot. The trap crop species has no important effect on the yield of cabbage, since the pests on trap crop plants were not control with insecticides.

Trap crops for reducing damage caused by cabbage stink bugs (Eurydema spp.) and flea beetles (Phyllotreta spp.) on white cabbage: fact or fantasy?

We studied the extent of damage by cabbage flea beetles on four different Brassica species in a two-year field experiment (2009–2010) at two locations in Slovenia. The entire experiment was based on testing oilseed rape, white mustard and oil radish as potential trap crops to protect cabbage from cabbage flea beetles. A significant influence of the Brassica species on the feeding by the flea beetles was confirmed at both locations. The damage index on oil radish was the highest throughout most of the growth period, whereas oilseed rape and white mustard were preferred only during a certain growth period. The initial damage by the cabbage flea beetles occurred in the first half of May, whereas the greatest damage occurred at the beginning of July. The research shows that the onset of cabbage flea beetle feeding can be controlled in a medium-late cabbage cultivar using trap cropping. However, because none of the tested trap crops strongly attracted the flea beetles throughout the entire growing per...

Sowing mixtures of Brassica trap crops is recommended to reduce Phyllotreta beetles injury to cabbage

This study describes the effects of environmental factors: the average and highest daily temperature, average relative air humidity, and the duration of the daily solar radiation, on the glucosinolate content in Brassicaceae. The results of our study indicate that the content of indole glucosinolate, glucobrassicin, is influenced by the average daily and the highest air temperature. Indole glucosinolates were much more susceptible to environmental factors than aliphatic or aromatic glucosinolates. Although the impact of the environment on the groups of aliphatic and aromatic glucosinolates was variable, there was a significant impact of the environment on specific aliphatic or aromatic glucosinolates. We conclude that climatic conditions cannot be neglected in the future planning of cropping systems, as the results of our investigation showed the important effect of environmental factors on the glucosinolate content in Brassicaceae.

Tanja Bohinc

Papers

Glucosinolates in plant protection strategies: a review

Phytoseiid mites of Slovenia (Acari: Mesostigmata): new records and first description of the male of Amblyseius microorientalis

Trap crops for reducing damage caused by cabbage stink bugs (Eurydema spp.) and flea beetles (Phyllotreta spp.) on white cabbage: fact or fantasy?

Sowing mixtures of Brassica trap crops is recommended to reduce Phyllotreta beetles injury to cabbage

Environmental factors affecting the glucosinolate content in Brassicaceae