Previous work suggested that the apoplastic phenol composition and its interaction with apoplastic class III peroxidases (PODs) are decisive in the development or avoidance of manganese (Mn) toxicity in cowpea (Vigna unguiculata L.). This study characterizes apoplastic PODs with particular emphasis on the activities of specific isoenzymes and their modulation by phenols in the Mn-sensitive cowpea cultivar TVu 91 as affected by Mn and silicon (Si) supply. Si reduced Mn-induced toxicity symptoms without affecting the Mn uptake. Blue Native-PAGE combined with Nano-LC-MS/MS allowed identification of a range of POD isoenzymes in the apoplastic washing fluid (AWF). In Si-treated plants Mn-mediated induction of POD activity was delayed. Four POD isoenzymes eluted from the BN gels catalysed both H2O2-consuming and H2O2-producing activity with pH optima at 6.5 and 5.5, respectively. Four phenols enhanced NADH-peroxidase activity of these isoenzymes in the presence of Mn2+ (p-coumaric=vanillic>>benzoic>ferulic acid). p-Coumaric acid-enhanced NADH-peroxidase activity was inhibited by ferulic acid (50%) and five other phenols (50–90%). An independent component analysis (ICA) of the total and apoplastic GC-MS-based metabolome profile showed that Mn, Si supply, and the AWF fraction (AWFH2O, AWFNaCl) significantly changed the metabolite composition. Extracting non-polar metabolites from the AWF allowed the identification of phenols. Predominantly NADH-peroxidase activity-inhibiting ferulic acid appeared to be down-regulated in Mn-sensitive (+Mn, –Si) and up-regulated in Mn-tolerant (+Si) leaf tissue. The results presented here support the previously hypothesized role of apoplastic NADH-peroxidase and its activity-modulating phenols in Mn toxicity and Si-enhanced Mn tolerance.
Type of publicationArticle ( AbstractPurpose: Trainers and organisations in heavily regulated industries face a number of trainingrelated HR challenges. The purpose of this paper is to examine barriers and propose solutions in such circumstances. Approach: The paper briefly outlines the results of a case study involving multi-method data collection (interview, survey, focus groups) to explore barriers to training effectiveness in a pharmaceutical company in Germany. Findings:The case study suggests that the company in question experienced several time and resource pressures to accommodate internally and externally required training needs. Other issues pertained to negative effects of these circumstances on employee motivation, engagement and relevance of training. Practical implications: Based on the case study and existing work, a number of general practical recommendations are outlined for trainers working in regulated industries. These include suggestions such as the need for situation awareness in the design of the training strategy, co-creation in training, the benefit of linking training to reward systems, training accreditation, and the benefit of reviewing existing training approaches in the regulated industry. Originality/value: The paper provides one starting point for those leading and managing training activities in regulated industry settings to manage the internal and external training challenges.
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