Plant Protection Bulletin (Taipei) (2006) 48, 311-330

W.M. Haggag and H. Abd El-Khair (2006)
Effect of polyamine biosynthesis inhibitors on the barley blotch pathogens and disease control
Plant Protection Bulletin (Taipei) 48 (4), 311-330
Abstract: The pathways of polyamines (PAs) biosynthesis and the effects of polyamine biosynthesis inhibitors on control of barley blotch diseases i.e. net blotch (Pyrenophora teres), strip blotch (Pyrenophora graminea), leaf blotch (Stagonospora avenae f. sp. triticea), and spot blotch (Cochliobolus sativus) were investigated. Five polyamine biosynthesis inhibitors, i.e. putrescine biosynthesis inhibitors [DL-alpha-difluoromethylarginine (DFMA) and DL-alpha-difluoromethylornithine (DFMO)] and spermidine biosynthesis inhibitors [berenil, cyclohexylamine and pentamidine] were tested. Conidia germination and fungal hyphal growth of four blotch pathogens were substantially reduced by DFMO, berenil, cyclohexylamine and pentamidine at low concentrations. Growth of blotch pathogens in the presence of 100 µgl putrescine biosynthesis inhibitors DFMA, greatly decreased polyamines levels of putrescine, spermidine and spermine as well as ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (AdoMetDC) and polyamine oxidase (PAO) activities in all pathogenic fungi tested. Berenil, cyclohexylamine and pentamidine also significantly decreased spermidine, spermine, AdoMetDC and PAO activities of these fungi. In greenhouse, blotch diseases severity was substantially reduced by all tested concentrations of polyamines biosynthesis inhibitors. ODC activity was reduced in leaves treated with DFMO and increased in the presence of DFMA. Meanwhile, arginine decarboxylase activity was reduced in leaves treated with DFMA and increased in the presence of DFMO. At the same time, putrescine biosynthesis inhibitors DFMO, DFMA as well as the spermidine biosynthesis inhibitors berenil, cyclohexylamine, and pentamidine did not decrease polyamine levels in barley plants. These compounds also controlled barely blotch diseases at low concentrations under natural infected conditions. The most effective treatment was DFMO at 1 mM. However, similar effect was also obtained by berenil at 1 mM. The treated plants showed significant increase in the plant growth and final yield, compared with untreated control. These results suggest that PAs are essential for the growth of fungi and that inhibitors of polyamine biosynthesis are applicable to the alleviation or prevention of crop losses due to these phytopathogenic fungi.
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Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pyrenophora teres	Barley (Hordeum vulgare)	Taiwan
	Pyrenophora graminea	Barley (Hordeum vulgare)	Taiwan
	Bipolaris sorokiniana	Barley (Hordeum vulgare)	Taiwan
	Parastagonospora avenae	Barley (Hordeum vulgare)	Taiwan