Glucosinolates are a category of secondary products present primarily in species of the order Capparales. When tissue is damaged, for example by herbivory, glucosinolates are degraded in a reaction catalyzed by thioglucosidases, denoted myrosinases, also present in these species. Thereby, toxic compounds such as nitriles, isothiocyanates, epithionitriles and thiocyanates are released. The glucosinolate-myrosinase system is generally believed to be part of the plant's defense against insects, and possibly also against pathogens. In this review, the evolution of the system and its impact on the interaction between plants and insects are discussed. Further, data suggesting additional functions in the defense against pathogens and in sulfur metabolism are reviewed.

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Glucosinolates are a category of secondary products present primarily in species of the order Capparales. When tissue is damaged, for example by herbivory, glucosinolates are degraded in a reaction catalyzed by thioglucosidases, denoted myrosinases, also present in these species. Thereby, toxic compounds such as nitriles, isothiocyanates, epithionitriles and thiocyanates are released. The glucosinolate-myrosinase system is generally believed to be part of the plant's defense against insects, and possibly also against pathogens. In this review, the evolution of the system and its impact on the interaction between plants and insects are discussed. Further, data suggesting additional functions in the defense against pathogens and in sulfur metabolism are reviewed.

The phylogenetic relationships of 17 Bacillus strains isolated from plants and soil were determined from partial sequences of genes encoding 16S rRNA, gyraseA (gyrA) and the cheA histidine kinase. Five strains were closely related to Bacillus subtilis subsp. subtilis, three strains were more closely related to B. subtilis subsp. spizizeni and two strains were identified as B. mojavensis. The remaining seven strains formed a cluster closely related to, but distinct from, Bacillus amyloliquefaciens. Some of these strains formed red-pigmented colonies. The abilities of selected strains to survive in the rhizosphere and to colonize plants were studied using oilseed rape (Brassica napus), barley (Hordeum vulgare) and thale cress (Arabidopsis thaliana) as model plants. It was shown by following the titre of bacteria in seedlings and by scanning electron microscopy that survival of Bacillus cells on the roots of seedlings during the first week after treatment of seeds with spore suspensions was crucial for colonization of the rhizosphere and for biocontrol activity. The group of strains related to B. amyloliquefaciens were generally better adapted to colonization of the rhizosphere of plants than other members of the B. subtilis group and could be considered a distinct ecotype of B. amyloliquefaciens. Bacteria in this taxon could be recognized on the basis of amplification of a PCR product with primers directed to the tetB(L) locus but no product with primers directed to the alpha-amylase gene of B.amyloliquefaciens sensu stricto.

Potato tubers naturally contain a number of defense substances, some of which are of major concern for food safety. Among these substances are the glycoalkaloids and calystegines. We have here analyzed levels of glycoalkaloids (α-chaconine and α-solanine) and calystegines (A₃, B₂, and B₄) in potato tubers subjected to mechanical wounding, light exposure, or elevated temperature: stress treatments that are known or anticipated to induce glycoalkaloid levels. Basal glycoalkaloid levels in tubers varied between potato cultivars. Wounding and light exposure, but not heat, increased tuber glycoalkaloid levels, and the relative response differed among the cultivars. Also, calystegine levels varied between cultivars, with calystegine B4 showing the most marked variation. However, the total calystegine level was not affected by wounding or light exposure. The results demonstrate a strong variation among potato cultivars with regard to postharvest glycoalkaloid increases, and they suggest that the biosynthesis of glycoalkaloids and calystegines occurs independently of each other.