Chromosome Genome Sequencing and Comparative Transcriptome-Based Analyses of Kloeckera apiculata 34-9 Unveil the Potential Biocontrol Mechanisms Against Citrus Green Mold

Biological control is an environmentally friendly, safe, and replaceable strategy for disease management. Genome sequences of a certain biocontrol agent could lay a solid foundation for the research of molecular biology, and the more refined the reference genome, the more information it provides. In the present study, a higher resolution genome of Kloeckera apiculata 34-9 was assembled using high-throughput chromosome conformation capture (Hi-C) technology. A total of 8.07 M sequences of K. apiculata 34-9 genome was anchored onto 7 pesudochromosomes, which accounting for about 99.51% of the whole assembled sequences, and 4,014 protein-coding genes were annotated. Meanwhile, the detailed gene expression changes of K. apiculata 34-9 were obtained under low temperature and co-incubation with Penicillium digitatum treatments, respectively. Totally 254 differentially expressed genes (DEGs) were detected with low temperature treatment, of which 184 and 70 genes were upregulated and downregulated, respectively. Some candidate genes were significantly enriched in ribosome biosynthesis in eukaryotes and ABC transporters. The expression of gene Kap003732 and Kap001595 remained upregulated and downregulated through the entire time-points, respectively, indicating that they might be core genes for positive and negative response to low temperature stress. When co-incubation with P. digitatum, a total of 2,364 DEGs were found, and there were 1,247 upregulated and 1,117 downregulated genes, respectively. Biosynthesis of lysine and arginine, and phenylalanine metabolism were the highest enrichment of the cluster and KEGG analyses of the co-DEGs, the results showed that they might be involved in the positive regulation of K. apiculata 34-9 response to P. digitatum. The completeness of K. apiculata 34-9 genome and the transcriptome data presented here are essential for providing a high-quality genomic resource and it might serve as valuable molecular properties for further studies on yeast genome, expression pattern of biocontrol system, and postharvest citrus storage and preservation.

Onychomycosis Caused by Kloeckera apiculata: A Case Report in a Patient with Multiple Sclerosis

We report the first case of onychomycosis caused by <i>Kloeckera apiculata</i> in a woman with multiple sclerosis. Video-dermoscopic examination showed a spiked pattern and distal irregular aspect. Colonies on Sabouraud agar were white, creamy, and smooth. A microscopic examination showed blastoconidia. MALDI-TOF confirmed <i>Kloeckera apiculata</i> as the causal agent.

Genome-wide identification, characterization and expression analysis of lineage-specific genes within Hanseniaspora yeasts

ABSTRACT Lineage-specific genes (LSGs) are defined as genes with sequences that are not significantly similar to those in any other lineage. LSGs have been proposed, and sometimes shown, to have significant effects in the evolution of biological function. In this study, two sets of Hanseniaspora spp. LSGs were identified by comparing the sequences of the Kloeckera apiculata genome and of 80 other yeast genomes. This study identified 344 Hanseniaspora-specific genes (HSGs) and 109 genes (‘orphan genes’) specific to K. apiculata. Three thousand three hundred thirty-one K. apiculata genes that showed significant similarity to at least one sequence outside the Hanseniaspora were classified into evolutionarily conserved genes. We analyzed their sequence features, functional categories, gene origin, gene structure and gene expression. We also investigated the predicted cellular roles and Gene Ontology categories of the LSGs using functional inference. The patterns of the functions of LSGs do not deviate significantly from genome-wide average. The results showed that a few LSGs were formed by gene duplication, followed by rapid sequence divergence. Many of the HSGs and orphan genes exhibited altered expression in response to abiotic stress. Studying these LSGs might be helpful for understanding the molecular mechanism of yeast adaption.

The Shared and Specific Genes and a Comparative Genomics Analysis within Three Hanseniaspora Strains

Kloeckera apiculata plays an important role in the inhibition of citrus postharvest blue and green mould diseases. This study was based on the previous genome sequencing of K. apiculata strain 34-9. After homologous comparison, scaffold 27 was defined as the mitochondrial (mt) sequence of K. apiculata 34-9. The comparison showed a high level of sequence identity between scaffold 27 and the known mtDNA of Hanseniaspora uvarum. The genome sequence of H. vineae T02/19AF showed several short and discontinuous fragments homologous to the mtDNA of H. uvarum. The shared and specific genes of K. apiculata, H. uvarum, and H. vineae were analysed by family using the TreeFam methodology. GO analysis was used to classify the shared and specific genes. Most of the gene families were classified into the functional categories of cellular component and metabolic processes. The whole-genome phylogram and genome synteny analysis showed that K. apiculata was more closely related to H. uvarum than to H. vineae. The genomic comparisons clearly displayed the locations of the homologous regions in each genome. This analysis could contribute to discovering the genomic similarities and differences within the genus Hanseniaspora. In addition, some regions were not collinearity-matched in the genome of K. apiculata compared with that of H. uvarum or H. vineae, and these sequences might have resulted from evolutionary variations.

Glycolytic Functions Are Conserved in the Genome of the Wine Yeast Hanseniaspora uvarum, and Pyruvate Kinase Limits Its Capacity for Alcoholic Fermentation

ABSTRACT Hanseniaspora uvarum (anamorph Kloeckera apiculata ) is a predominant yeast on wine grapes and other fruits and has a strong influence on wine quality, even when Saccharomyces cerevisiae starter cultures are employed. In this work, we sequenced and annotated approximately 93% of the H. uvarum genome. Southern and synteny analyses were employed to construct a map of the seven chromosomes present in a type strain. Comparative determinations of specific enzyme activities within the fermentative pathway in H. uvarum and S. cerevisiae indicated that the reduced capacity of the former yeast for ethanol production is caused primarily by an ∼10-fold-lower activity of the key glycolytic enzyme pyruvate kinase. The heterologous expression of the encoding gene, H. uvarum PYK1 ( HuPYK1 ), and two genes encoding the phosphofructokinase subunits, HuPFK1 and HuPFK2 , in the respective deletion mutants of S. cerevisiae confirmed their functional homology. IMPORTANCE Hanseniaspora uvarum is a predominant yeast species on grapes and other fruits. It contributes significantly to the production of desired as well as unfavorable aroma compounds and thus determines the quality of the final product, especially wine. Despite this obvious importance, knowledge on its genetics is scarce. As a basis for targeted metabolic modifications, here we provide the results of a genomic sequencing approach, including the annotation of 3,010 protein-encoding genes, e.g., those encoding the entire sugar fermentation pathway, key components of stress response signaling pathways, and enzymes catalyzing the production of aroma compounds. Comparative analyses suggest that the low fermentative capacity of H. uvarum compared to that of Saccharomyces cerevisiae can be attributed to low pyruvate kinase activity. The data reported here are expected to aid in establishing H. uvarum as a non- Saccharomyces yeast in starter cultures for wine and cider fermentations.