Growth and toxin production of phomopsin A and ochratoxin A forming fungi under different storage conditions in a pea (Pisum sativum) model system

Phomopsins are mycotoxins mainly infesting lupines, with phomopsin A (PHOA) being the main mycotoxin. PHOA is produced by Diaporthe toxica, formerly assigned as toxigenic Phomopsis leptostromiformis, causing infections in lupine plants and harvested seeds. However, Diaporthe species may also grow on other grain legumes, similar to Aspergillus westerdijkiae as an especially potent ochratoxin A (OTA) producer. Formation of PHOA and OTA was investigated on whole field peas as model system to assess fungal growth and toxin production at adverse storage conditions. Field pea samples were inoculated with the two fungal strains at two water activity (aw) values of 0.94 and 0.98 and three different levels of 30, 50, and 80% relative air humidity.After 14 days at an aw value of 0.98, the fungi produced 4.49 to 34.3 mg/kg PHOA and 1.44 to 3.35 g/kg OTA, respectively. Strains of D. toxica also tested showed higher PHOA concentrations of 28.3 to 32.4 mg/kg.D. toxica strains did not grow or produce PHOA at an aw values of 0.94, while A. westerdijkiae still showed growth and OTA production.Elevated water activity has a major impact both on OTA and, even more pronouncedly, on PHOA formation and thus, proper drying and storage of lupins as well as other grain legumes is crucial for product safety.

Agresywność i patogeniczność Phomopsis leptostromiformis (Kühn) Bubak i Rozwój procesu chorobowego powodowanego przez ten grzyb[Aggressiveness and pathogenicity of Phomopsis leptostromijormis (Kühn) Bubak and the development of the pathologic process caused by this fungus]

Numerous experiments were performed with infection of plants in glasshouse conditions. Various concentrations of inoculum were applied and it was found that the fungus <i>Phomopsis leptostromiformis</i> has a very strong aggressiveness and pathogenicity towards <i>Lupinus luteus, L. albus, L. angustifolius</i> and <i>L. polyphyllus</i>. It was established that the infection phase for the fungus lasts 36 h. the incubation phase 60 h and disease appears 96 h after inoculation.

Patogenic fungi associated with blue lupine seeds

Over 10% ofseeds harvested in 1991 and 1992 (50 samples, 400 seeds in each sample) proved to be infested with various fungi. <em>Fusarium</em> spp. and <em>Botrytis cinerea</em> were the most common pathogens isolated. <em>Fusarium avenaceum</em> was the most common and highIy pathogenic species. <em>Fusarium semitectum</em> and <em>F. tricinctum</em> were highly pathogenic to lupin seedlings but they were the least common <em>Fusarium</em> isolated from seeds. Similarily, <em>Sclerotinia sclerotiorum</em> was isolated only from 0,2% seeds tested but this fungus was highly pathogenic to lupin seedlings. Some other fungi know as lupin pathogens (<em>F. oxysporum, Stemphylium botryosum, Pleiochaeta setosa</em> and <em>Phomopsis leptostromiformis</em>) were also noted in tested seeds.

Phomopsins: an overview of phytopathological and chemical aspects, toxicity, analysis and occurrence

Phomopsis leptostromiformis, and its teleomorph Diaporthe toxica, is a lupin pathogen that causes stem blight in young lupins and, as a saprophyte, has been detected on dead lupine material. Under favourable conditions, the fungus produces phomopsins (PHOs), a family of macrocyclic hexapeptide mycotoxins capable of binding tubulin through the tripeptide side chain. The toxic effects appear largely confined to the liver. In particular, the ingestion of PHO contaminated lupin stubble has been linked to lupinosis, a debilitating disease of sheep (the most sensitive animal) characterised by disorientation, blindness, lethargy, and eventually death. The chemical structures of PHO A, B and D have been identified. Analytical methods to determine PHOs are mainly enzyme-linked immunosorbent assays or chromatographic separations, in combination with ultraviolet and mass spectrometric detection. The data about the PHOs occurrence are limited to Australia, restricted to lupin seed. Only one survey has been carried out on lupin seeds and flours from the Swiss market. Not many strategies have been developed to limit lupin seed contamination. Efforts devoted to control lupinosis in Australia focused on the development of cultivars resistant to Phomopsis infection. There are few examples in literature of decontamination or detoxification of PHOs; moreover, they have been shown to be resistant to extensive processing, including cooking. Australia and New Zealand are the only countries that included PHOs in their mycotoxin regulations, with a limit of 5 µg/kg in lupin seeds and derived products. Phomopsins are poorly studied mycotoxins and risk assessment on PHOs has not been done at the European level. The collection of all available scientific data was requested by EFSA in a specific project and partners involved considered it of general interest preparing this review to highlight the limited available information, which indicate that the assessment of potential risk related to PHOs is currently not feasible.

New chaetoglobosins from maize infested byPhomopsis leptostromiformisfungi. Production, identification, and semi‒synthesis

This paper deals with the cytotoxic chaetoglobosins obtained from culture on maize of the strains ATCC 26115 and MRC 2654 of the fungusPhomopsis leptostromiformisBoth strains produced, in more or less important amounts, the known chaetoglobosins M (1) and N (2). In addition, the new chaetoglobosin O (3), was isolated from the ATCC 26115 strain and characterized by HRMS and 2D NMR experiments. With the MRC 2654 strain, a fungal metabolite4, more polar than the chaetoglobosins M and N, was extracted and purified. Spectroscopic and chromatographic data of metabolite4led to its identification to the bridged chaetoglobosin named compoundS, which previously has been obtained by intramolecular Michael reaction on the chaetoglobosin M. Moreover, a methylation under Williamson conditions of the chaetoglobosin4resulted in the formation of the trimethylated chaetoglobosin5.

Monitoring the toxicity of lupin (Lupinus angustifolius) stubbles has limited value in the prevention of lupinosis

Lupin (Lupinus angustifolius) stubbles at 3 'sentinel' sites in the Midlands Region of Western Australia were monitored throughout the summer of 1985-86 to assess the level of infection of the stems by the fungus Phomopsis leptostromiformis, and to measure the concentration of its toxic product, phomopsin A. These parameters were found to have little value as predictors of fungal infection and of the toxicity of lupin stubbles on farms in surrounding districts. It was found also that visual rating of the level of P. leptostromiforrnis infection of lupin stems was unrelated to the concentration of phomopsin A in those stems or to the liver damage in sheep grazing stubble from which the stems were sampled. It is suggested that these ratings should not be used to advise farmers on the 'lupinosis risk' of a lupin stubble. Monitoring the phomopsin A concentration in lupin stems collected throughout a summer confirmed that rain, associated with cloudy days, was the primary environmental stimulus to a significant increase in the phomopsin A concentration.

Control of Pleiochaeta setosa diseases of lupin using seed and fertiliser applied fungicides

Control of Pleiochaeta setosa diseases of lupins was compared in 8 field experiments using Rovral (iprodione) and Sumisclex (procymidone) as either seed dressing or fertiliser-applied treatments. Seed-dressing application was more effective than fertiliser application for control of brown spot. Rovral and Sumisclex provided very similar control of brown spot in most comparisons, but Sumisclex occasionally provided significantly better control. Pleiochaeta root rot was controlled by Rovral seed treatment at 1 location and by all Rovral and Sumisclex treatments at a second location. When used at 1 location, Armour (flutriafol) on superphosphate provided significant control of brown spot but not pleiochaeta root rot. Fungicide seed treatment did not reduce Phomopsis leptostromiformis stem lesioning. Significant yield improvement following fungicidal control of P. setosa occurred in 4 experiments.