弗吉尼亚生物信息研究所及杜克大学医疗中心的科学家，精确地定位了对于十字花科黑斑病菌(Alternaria brassicicola)发育和产生毒性相当重要的一个基因。
十字花科黑斑病菌会感染十字花科蔬菜。发病初期，叶表面出现淡褐色斑点，逐渐扩大，形成褐色不正形受叶脉限制之病斑，四周呈黄色，背面则生出白色霜霉状物（分生孢子）。容易受到十字花科黑斑病菌感染的农作物包括甘蓝、花椰菜、萝卜、芜菁等。
此外，十字花科黑斑病菌也会导致人类的呼吸道疾病，例如过敏、气喘，和慢性鼻窦炎。
研究人员表示，AbNPS2 基因如果受到破坏，会显著地影响霉菌孢子细胞壁的完整性，这个基因可能负责合成与孢子的细胞壁结构有关的分子。
因此当AbNPS2 基因发生突变，孢子细胞壁受到破坏而降低了孢子萌芽率，所以孢子在有害的环境下之存活率也会变低，而十字花科黑斑病菌对于宿主植物造成的影响也会减弱。这些研究结果有助于研发出新的策略，来对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.
