Aylward Janneke, Wingfield Brenda D, Dreyer Léanne L, Roets Francois, Wingfield Michael J, Steenkamp Emma T
Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa; Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa.
Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa.
Fungal Biol. 2018 Dec;122(12):1201-1214. doi: 10.1016/j.funbio.2018.10.001. Epub 2018 Oct 23.
Genome comparisons of species with distinctive ecological traits can elucidate genetic divergence that influenced their differentiation. The interaction of a microorganism with its biotic environment is largely regulated by secreted compounds, and these can be predicted from genome sequences. In this study, we considered Knoxdaviesia capensis and Knoxdaviesia proteae, two closely related saprotrophic fungi found exclusively in Protea plants. We investigated their genome structure to compare their potential inter-specific interactions based on gene content. Their genomes displayed macrosynteny and were approximately 10 % repetitive. Both species had fewer secreted proteins than pathogens and other saprotrophs, reflecting their specialized habitat. The bulk of the predicted species-specific and secreted proteins coded for carbohydrate metabolism, with a slightly higher number of unique carbohydrate-degrading proteins in the broad host-range K. capensis. These fungi have few secondary metabolite gene clusters, suggesting minimal competition with other microbes and symbiosis with antibiotic-producing bacteria common in this niche. Secreted proteins associated with detoxification and iron sequestration likely enable these Knoxdaviesia species to tolerate antifungal compounds and compete for resources, facilitating their unusual dominance. This study confirms the genetic cohesion between Protea-associated Knoxdaviesia species and reveals aspects of their ecology that have likely evolved in response to their specialist niche.
对具有独特生态特征的物种进行基因组比较，可以阐明影响其分化的遗传差异。微生物与其生物环境的相互作用很大程度上受分泌化合物的调控，而这些化合物可以从基因组序列中预测出来。在本研究中，我们研究了卡氏诺克斯戴维斯菌（Knoxdaviesia capensis）和普罗梯亚木诺克斯戴维斯菌（Knoxdaviesia proteae），这两种密切相关的腐生真菌仅在山龙眼属植物中发现。我们研究了它们的基因组结构，以基于基因含量比较它们潜在的种间相互作用。它们的基因组显示出宏观共线性，约10%为重复序列。与病原体和其他腐生菌相比，这两个物种的分泌蛋白都较少，这反映了它们特殊的栖息地。预测的物种特异性和分泌蛋白大多编码碳水化合物代谢，在宿主范围广的卡氏诺克斯戴维斯菌中，独特的碳水化合物降解蛋白数量略多。这些真菌的次生代谢物基因簇很少，这表明它们与其他微生物的竞争最小，并且与该生态位中常见的产生抗生素的细菌共生。与解毒和铁螯合相关的分泌蛋白可能使这些诺克斯戴维斯菌能够耐受抗真菌化合物并竞争资源，从而促进它们不同寻常的优势地位。这项研究证实了与山龙眼属相关的诺克斯戴维斯菌物种之间的遗传凝聚力，并揭示了它们的生态学方面可能是为了适应其特殊生态位而进化的。
