Varady Erika S, Bodaghi Sohrab, Vidalakis Georgios, Douhan Greg W
Department of Microbiology and Plant Pathology, University of California, Riverside, California.
Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California.
Microbiologyopen. 2019 Jul;8(7):e00788. doi: 10.1002/mbo3.788. Epub 2019 Jan 30.
Penicillium digitatum is one of the most important postharvest pathogens of citrus on a global scale causing significant annual losses due to fruit rot. However, little is known about the diversity of P. digitatum populations. The genome of P. digitatum has been sequenced, providing an opportunity to determine the microsatellite distribution within P. digitatum to develop markers that could be valuable tools for studying the population biology of this pathogen. In the analyses, a total of 3,134 microsatellite loci were detected; 66.73%, 23.23%, 8.23%, 1.24%, 0.16%, and 0.77% were detected as mono-, di-, tri-, tetra-, penta-, and hexanucleotide repeats, respectively. As consistent with other ascomycete fungi, the genome size of P. digitatum does not seem to correlate with the density of microsatellite loci. However, significantly longer motifs of mono-, di-, and tetranucleotide repeats were identified in P. digitatum compared to 10 other published ascomycete species with repeats of over 800, 300, and 900 motifs found, respectively. One isolate from southern California and five additional isolates from other countries ("global isolates") were used to initially screen microsatellite markers developed in this study. Twelve additional isolates, referred to as the "local isolates," were also collected from citrus at the University of California Riverside agricultural experiment station and were subsequently used to screen the primers that sequenced well and were polymorphic based on the global isolates. Thirty-six primers were screened, and nine trinucleotide loci and one hexanucleotide locus were chosen as robust markers. These loci yielded two to seven alleles and will be useful to study population genetic structure of P. digitatum populations.
指状青霉是全球范围内柑橘采后最重要的病原菌之一，因果实腐烂每年造成重大损失。然而，人们对指状青霉种群的多样性了解甚少。指状青霉的基因组已被测序，这为确定指状青霉内微卫星的分布提供了机会，以便开发出对研究该病原菌种群生物学有价值的工具。在分析中，共检测到3134个微卫星位点；分别检测到单核苷酸、二核苷酸、三核苷酸、四核苷酸、五核苷酸和六核苷酸重复序列的比例为66.73%、23.23%、8.23%、1.24%、0.16%和0.77%。与其他子囊菌真菌一致，指状青霉的基因组大小似乎与微卫星位点的密度无关。然而，与其他10个已发表的子囊菌物种相比，指状青霉中鉴定出的单核苷酸、二核苷酸和四核苷酸重复序列的基序明显更长，分别发现了超过800、300和900个基序的重复。来自南加州的一个分离株和来自其他国家的另外五个分离株（“全球分离株”）被用于初步筛选本研究中开发的微卫星标记。另外12个分离株，称为“本地分离株”，也从加利福尼亚大学河滨分校农业实验站的柑橘中收集，随后用于筛选基于全球分离株测序良好且具有多态性的引物。筛选了36对引物，选择了9个三核苷酸位点和1个六核苷酸位点作为可靠的标记。这些位点产生了2至7个等位基因，将有助于研究指状青霉种群的群体遗传结构。
