弗吉尼亞生物信息研究所及杜克大學(xué)醫(yī)療中心的科學(xué)家，精確地定位了對(duì)于十字花科黑斑病菌(Alternaria brassicicola)發(fā)育和產(chǎn)生毒性相當(dāng)重要的一個(gè)基因,。
十字花科黑斑病菌會(huì)感染十字花科蔬菜,。發(fā)病初期，葉表面出現(xiàn)淡褐色斑點(diǎn),，逐漸擴(kuò)大,，形成褐色不正形受葉脈限制之病斑,，四周呈黃色,，背面則生出白色霜霉?fàn)钗铮ǚ稚咦樱?。容易受到十字花科黑斑病菌感染的農(nóng)作物包括甘藍(lán)、花椰菜,、蘿卜,、蕪菁等。
此外,，十字花科黑斑病菌也會(huì)導(dǎo)致人類的呼吸道疾病,，例如過敏、氣喘,，和慢性鼻竇炎,。
研究人員表示,，AbNPS2 基因如果受到破壞,，會(huì)顯著地影響霉菌孢子細(xì)胞壁的完整性，這個(gè)基因可能負(fù)責(zé)合成與孢子的細(xì)胞壁結(jié)構(gòu)有關(guān)的分子,。
因此當(dāng)AbNPS2 基因發(fā)生突變,，孢子細(xì)胞壁受到破壞而降低了孢子萌芽率，所以孢子在有害的環(huán)境下之存活率也會(huì)變低,，而十字花科黑斑病菌對(duì)于宿主植物造成的影響也會(huì)減弱,。這些研究結(jié)果有助于研發(fā)出新的策略,，來對(duì)付十字花科黑斑病菌。
部分英文原文：
Functional analysis of the Alternaria brassicicola non-ribosomal peptide synthetase gene AbNPS2 reveals a role in conidial cell wall construction
Alternaria brassicicola is a necrotrophic pathogen causing black spot disease on virtually all cultivated Brassica crops worldwide. In many plant pathosystems fungal secondary metabolites derived from non-ribosomal peptide synthetases (NPSs) are phytotoxic virulence factors or are antibiotics thought to be important for niche competition with other micro-organisms. However, many of the functions of NPS genes and their products are largely unknown. In this study, we investigated the function of one of the A. brassicicola NPS genes, AbNPS2. The predicted amino acid sequence of AbNPS2 showed high sequence similarity with A. brassicae, AbrePsy1, Cochliobolus heterostrophus, NPS4 and a Stagonospora nodorum NPS. The AbNPS2 open reading frame was predicted to be 22 kb in length and encodes a large protein (7195 amino acids) showing typical NPS modular organization. Gene expression analysis of AbNPS2 in wild-type fungus indicated that it is expressed almost exclusively in conidia and conidiophores, broadly in the reproductive developmental phase. AbNPS2 gene disruption mutants showed abnormal spore cell wall morphology and a decreased hydrophobicity phenotype. Conidia of abnps2 mutants displayed an aberrantly inflated cell wall and an increase in lipid bodies compared with wild-type. Further phenotypic analyses of abnps2 mutants showed decreased spore germination rates both in vitro and in vivo, and a marked reduction in sporulation in vivo compared with wild-type fungus. Moreover, virulence tests on Brassicas with abnps2 mutants revealed a significant reduction in lesion size compared with wild-type but only when aged spores were used in experiments. Collectively, these results indicate that AbNPS2 plays an important role in development and virulence.
