Institute of Sciences of Food Production (ISPA-CNR), via Amendola 122/O, 70126 Bari, Italy.
Institute of Sciences of Food Production (ISPA-CNR), via Amendola 122/O, 70126 Bari, Italy.
Int J Food Microbiol. 2019 Mar 16;293:34-43. doi: 10.1016/j.ijfoodmicro.2019.01.001. Epub 2019 Jan 3.
Black point is one of the most important wheat disease and its incidence is increasing worldwide due to climate change too. Among the fungal genera that can cause black point, Alternaria is one of the predominant genus, often associated with mycotoxin contamination. The correct identification is the baseline for prevention and control of the disease. Taxonomy of the genus Alternaria is not completely clear yet, since its species can be differentiated for few morphological traits and, in some cases, also molecular phylogeny is not very effective in establishing species boundaries. In this study, one-hundred sixty-four strains, isolated from wheat kernels affected by black point sampled worldwide, were analyzed in order to assess their identity. Sequences of elongation factor, β-tubulin, glyceraldehyde-3-phosphate dehydrogenase and allergen alt-a1 genes were used to identify the variability of this population and their phylogenetic relationships. Isolates were grouped in two main clades: the Alternaria section, including A. alternata, A. tenuissima and A. arborescens species, and the Infectoriae section, that includes the two species A. infectoria and A. triticina. Comparison of isolates according with their area of isolation did not show a correlation between phylogeny and geographic origin. Indeed, the isolates grouped on the base of only their phylogenetic relationship. Due to the data arisen by our study, we strongly recommend a multilocus sequence approach to define Alternaria species, based on common genes and procedures to be unanimously shared by scientific community dealing with Alternaria genus. Moreover, we suggest that A. alternata, A. tenuissima, A. turkisafria and A. limoniasperae species would be merged in the defined species A. alternata. Finally we recommend to consider a taxonomic re-evaluation of the Infectoriae section that, for the morphology, sexuality, genetic and mycotoxin profile of the species included, could be defined as different fungal genus from Alternaria.
黑斑病是小麦的主要病害之一，由于气候变化，其发病率在全球范围内呈上升趋势。在引起黑斑病的真菌属中，交链孢属是主要属之一，常与真菌毒素污染有关。正确的鉴定是预防和控制该疾病的基础。交链孢属的分类尚未完全清楚，因为其种可以通过几个形态特征来区分，而且在某些情况下，分子系统发育也不能有效地确定物种界限。在这项研究中，分析了从全球范围内受黑斑病影响的小麦籽粒中分离出的 164 株菌株，以评估它们的身份。使用伸长因子、β-微管蛋白、甘油醛-3-磷酸脱氢酶和过敏原 alt-a1 基因的序列来识别该种群的变异性及其系统发育关系。分离物分为两个主要分支：交链孢属，包括 A. alternata、A. tenuissima 和 A. arborescens 种，以及 Infectoriae 属，包括 A. infectoria 和 A. triticina 两种。根据分离物的隔离区对其进行比较，并没有显示出系统发育与地理起源之间的相关性。实际上，分离物仅根据其系统发育关系进行分组。由于我们的研究结果，我们强烈建议采用多基因序列方法来定义交链孢属，基于共同的基因和程序，由处理交链孢属的科学界共同使用。此外，我们建议将 A. alternata、A. tenuissima、A. turkisafria 和 A. limoniasperae 种合并为定义的 A. alternata 种。最后，我们建议重新评估 Infectoriae 属，从包括的种的形态、性别、遗传和真菌毒素特征来看，它可能被定义为与交链孢属不同的真菌属。
