Search

Plants are constantly defending themselves against an array of assaults by pathogenic organisms. This has led to the evolution of precise and elaborate chemical defense systems involving glucosinolates (GSLs) in cruciferous plants. These GSLs and their hydrolysis products are biologically active and are implicated as enabling formidable plant defense processes in certain economically important members of Brassicaceae like broccoli, cabbage and mustard seed. This review provides a comprehensive report of how indole and aliphatic GSLs mitigate incidents of plant pathogenesis. By evaluating the roles of GSLs in plant-pathogen interaction of some brassica plants, this review highlights the associated mechanism that culminates in disease suppression. Moreover, seven economically important brassica pathogens were reviewed in terms of their ability to disrupt proper plant functioning as well as the mechanisms by which GSLs and their hydrolysis products in Brassica lower the susceptibility to them. Future perspectives of the application of GSLs in plant pathogen resistance using advanced molecular techniques are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Glucosinolates, a class of specialized metabolites specific to the order Brassicales, have diverse bioactivities that are largely dependent on the structures of their side chains. Flavin‐containing monooxygenases (FMOs) encoded by the FMOGS‐OX genes have been found to catalyze side‐chain modifications during the synthesis of methionine‐derived aliphatic glucosinolates. Seven FMOGS‐OX genes have been identified in Arabidopsis Heynh., but the evolution of these genes in the Brassicaceae, a family including many economically important vegetables, is poorly understood. In this study, the phylogenetic and syntenic relationships of the FMOGS‐OX genes belonging to 12 sequenced Brassicaceae species were analyzed. Our results showed that the FMOGS‐OX genes included two tandem arrays, the FMOGS‐OX2‐4 group (group A) and the FMOGS‐OX5‐7 group (group B). The evolutionary histories of the FMOGS‐OX groups A and B were similar across the Brassicaceae, but two lineage‐specific evolutionary routes developed after these two separate species lineages diverged from Aethionema arabicum (L.) Andrz. ex DC. In the lineage I route, FMOGS‐OX gene copies tended to increase due to frequent tandem duplication events in most species and a whole genome triplication in Camelina sativa (L.) Crantz. In the lineage II route, gene copies decreased due to deletion events. Combining these results with those of previous studies, we speculated that the FMOGS‐OX genes were derived from an ancestral gene with a broad expression distribution and a broad range of substrates, which then underwent subfunctionalization to generate progeny limited in either spatial expression or substrate structure. Furthermore, the absence of FMOGS‐OX5 substrates in some FMOGS‐OX5‐containing species may suggest neofunctionalization of these genes. [ABSTRACT FROM AUTHOR]

Glucosinolates are a class of amino acid-derived specialized metabolites characteristic of the Brassicales order. Trp derived indolic glucosinolates are essential for the effective plant defense responses to a wide range of pathogens and herbivores. In Arabidopsis, MYB51 is the key transcription factor positively regulates indolic glucosinolate production by activating certain biosynthetic genes. In this study, we report the isolation and identification of a MYB51 from broccoli designated as BoMYB51 . Overexpression of BoMYB51 in Arabidopsis increased indolic glucosinolate production by upregulating biosynthetic genes and resulted in enhanced flagellin22 (Flg22) induced callose deposition. The spatial expression pattern and responsive expression of BoMYB51 to several hormones and stress treatments were investigated by expressing the β-glucuronidase ( GUS ) reporter gene driven by BoMYB51 promotor in Arabidopsis and quantitative real-time PCR analysis in broccoli. Our study provides information on molecular characteristics of BoMYB51 and possible physiological process BoMYB51 may involve. [ABSTRACT FROM AUTHOR]