Insights into <i>Penicillium roqueforti</i> Morphological and Genetic Diversity

Fungi exhibit substantial morphological and genetic diversity, often associated with cryptic species differing in ecological niches. Penicillium roqueforti is used as a starter culture for blue-veined cheeses, being responsible for their flavor and color, but is also a common spoilage organism in various foods. Different types of blue-veined cheeses are manufactured and consumed worldwide, displaying specific organoleptic properties. These features may be due to the different manufacturing methods and/or to the specific P. roqueforti strains used. Substantial morphological diversity exists within P. roqueforti and, although not taxonomically valid, several technological names have been used for strains on different cheeses (e.g., P. gorgonzolae, P. stilton). A worldwide P. roqueforti collection from 120 individual blue-veined cheeses and 21 other substrates was analyzed here to determine (i) whether P. roqueforti is a complex of cryptic species, by applying the Genealogical Concordance Phylogenetic Species Recognition criterion (GC-PSR), (ii) whether the population structure assessed using microsatellite markers correspond to blue cheese types, and (iii) whether the genetic clusters display different morphologies. GC-PSR multi-locus sequence analyses showed no evidence of cryptic species. The population structure analysis using microsatellites revealed the existence of highly differentiated populations, corresponding to blue cheese types and with contrasted morphologies. This suggests that the population structure has been shaped by different cheese-making processes or that different populations were recruited for different cheese types. Cheese-making fungi thus constitute good models for studying fungal diversification under recent selection.真菌兼具丰富的形态学与遗传学多样性，此类多样性通常与生态位分化的隐秘物种密切相关。娄地青霉（Penicillium roqueforti）是蓝纹奶酪的发酵剂菌种，赋予其独特的风味与色泽，同时也是多种食品中常见的污染菌。全球范围内生产并消费的各类蓝纹奶酪均具有独特的感官品质，这类品质差异可能源于不同的生产工艺，或是所使用的娄地青霉菌株存在特异性。娄地青霉种内存在显著的形态学多样性；尽管此类名称在分类学上并不成立，但针对不同奶酪上的菌株，学界已使用了多个工艺学名称（如戈贡佐拉青霉（P. gorgonzolae）、斯蒂尔顿青霉（P. stilton））。本研究针对采自120份蓝纹奶酪及21份其他基质的全球娄地青霉菌株库开展分析，旨在达成三个研究目标：其一，通过谱系一致性系统发育物种识别（Genealogical Concordance Phylogenetic Species Recognition, GC-PSR）标准，判断娄地青霉是否为隐秘物种复合体；其二，评估基于微卫星标记解析的种群结构是否与蓝纹奶酪类型相匹配；其三，探究遗传聚类群是否呈现出不同的形态学特征。基于GC-PSR的多位点序列分析未发现存在隐秘物种的证据。基于微卫星标记的种群结构分析显示，存在多个高度分化的种群，这些种群与蓝纹奶酪类型一一对应，且形态学特征存在显著差异。这表明，娄地青霉的种群结构或受不同奶酪生产工艺的塑造，或是不同奶酪类型分别招募了特异性的娄地青霉种群。因此，奶酪发酵用真菌可作为研究近期选择压力下真菌类群分化的理想模型系统。