Department of Animal Sciences, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark.
Fungal Biol. 2012 Aug;116(8):855-62. doi: 10.1016/j.funbio.2012.04.014. Epub 2012 May 3.
The plant pathogen Fusarium graminearum is the infamous cause of Fusarium head blight worldwide resulting in significant losses of yield and reduced grain feed quality. It also has the potential to produce a range of small bioactive peptides produced by the non ribosomal peptide synthetases (NRPSs). Most of these are unknown as F. graminearum contains 19 NRPS encoding genes, but only three have been assigned products. For the first time, we use deletion and overexpression mutants to investigate the functions and product of NRPS4 in F. graminearum. Deletion of NRPS4 homologues in Alternaria brassicicola and Cochloibolus heterostrophus has been shown to result in mutants unable to repel water. In a time study of surface hydrophobicity we observed that water droplets could penetrate 7 d old colonies of the NRPS4 deletion mutants. Loss in ability to repel water was first observed on 13 d old cultures of the wild type strain, whereas the overexpression strain remained water repellant throughout the 38 d time study. The conidia of both mutants were examined and those of the overexpression mutant showed distinct morphological differences in form of collapsed cells. These observations might suggest that the peptide product of NRPS4 could be an architectural factor in the cell walls of Fusarium or an indirect regulator of hydrophobicity.
植物病原菌禾谷镰刀菌是造成全世界镰孢穗枯病的元凶，导致产量显著下降和粮食饲料质量降低。它还有可能产生一系列由非核糖体肽合成酶（NRPSs）产生的小分子生物活性肽。这些肽中的大多数都不为人知，因为禾谷镰刀菌含有 19 个 NRPS 编码基因，但只有 3 个被分配了产物。我们首次使用缺失和过表达突变体来研究 NRPS4 在禾谷镰刀菌中的功能和产物。在链格孢菌和玉蜀黍旋孢腔菌中，NRPS4 同源物的缺失已被证明会导致无法排斥水的突变体。在表面疏水性的时间研究中，我们观察到水滴可以渗透到 NRPS4 缺失突变体 7 天龄的菌落中。在野生型菌株的 13 天龄培养物中，首先观察到排斥水的能力丧失，而过表达菌株在 38 天的时间研究中一直保持拒水状态。对两个突变体的分生孢子进行了检查，过表达突变体的分生孢子在形态上表现出明显的差异，细胞塌陷。这些观察结果可能表明，NRPS4 的肽产物可能是细胞壁的结构因子，或者是疏水性的间接调节剂。
