부산대학교 도서관

Many members of the genus Fusarium can infect plants. Fusarium graminearum (Fg) species complex such as F. graminearum that can cause Fusarium head blight. Fg conidia can serve as secondary inoculum, spread by wing and infect plant parts above ground (e.g. head of wheat) repeatedly. Ascospores or conidia produced from sexual or asexual reproduction in Fg can both serve as inoculum. Fusarium oxysporum f. sp. lycopersici (Fol) used to cause damage up to one-third of tomato fields in 1982 in Kaohsiung, Taiwan. Many tomato cultivars bred in Taiwan emphasize the trait of resistance to Fusarium wilt. Currently, there are few recommended fungicides for controlling Fusarium infections in Taiwan. Phospholipids are main material of biological membranes, including phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylcholine (PC) and others. Compare to other kinds of phospholipids, PE can increase the nonbilayer-forming ability of membrane easily. This ability plays an important role in fusion and fission of membrane, and movement of embedded protein in membrane. Phosphatidylserine decarboxylase (Psd) including Psd2 takes part in PE formation of fungi. In this study, two independent Δpsd2 mutants each from F. graminearum PH-1 or F. oxysporum f. sp. lycopersici 4287 were constructed. The function of PSD2 on PE production, growth, production of conidia or chlamydospores, and virulence in the plant hosts were carefully examined. Comparing the strains grown in the absence or presence of ethanolamine (Etn) in minimal medium (MM), Δpsd2 mutants from either Fg or Fol exhibited Etn auxotrophy. Δpsd2 mutants of both Fg and Fol grew slower on MM and PDA media, while similar on barley bran media compared with their respective wild types. Meanwhile, PSD2 gene affected conidiation of Fg in addition to regulating the germination rate of conidia and formation of chlamydospores of Fol. Although PSD2 gene affected secretion of extracellular enzymes of Fg but not Fol, it is dispensable to virulence on wheat or tomato.