Cryptococcosis, a mycosis presenting mostly as meningoencephalitis, affecting predominantly human immunodeficiency virus (HIV)-infected people, is mainly caused by Cryptococcus neoformans. The genetic variation of 48 C. neoformans isolates, recovered from 20 HIV-positive people in Lima, Peru, during the pre-highly active antiretroviral therapy (HAART) era, was studied retrospectively. The mating type of the isolates was determined by PCR, and the serotype by agglutination and CAP59-restriction fragment length polymorphism (RFLP). Genetic diversity was assessed by URA5-RFLP, PCR-fingerprinting, amplified fragment length polymorphism (AFLP), and multilocus sequence typing (MLST). All isolates were mating type alpha, with 39 molecular type VNI, seven VNII, corresponding to C. neoformans var. grubii serotype A, and two VNIII AD hybrids. Overall, the cryptococcal population from HIV-positive people in Lima shows a low degree of genetic diversity. In most patients with persistent cryptococcal infection, the same genotype was recovered during the follow-up. In four patients with relapse and one with therapy failure, different genotypes were found in isolates from the re-infection and from the isolate recovered at the end of the treatment. In one patient, two genotypes were found in the first cryptococcosis episode. This study contributes data from Peru to the ongoing worldwide population genetic analysis of Cryptococcus.

DNA barcoding is a powerful method for the identification of lichenized fungi groups for which the diversity is already well-represented in nucleotide databases, and an accurate, robust taxonomy has been established. However, the effectiveness of DNA barcoding for identification is expected to be limited for understudied taxa or regions. One such region is Antarctica, where, despite the importance of lichens and lichenized fungi identification, their genetic diversity is far from characterized. The aim of this exploratory study was to survey the lichenized fungi diversity of King George Island using a fungal barcode marker as an initial identification tool. Samples were collected unrestricted to specific taxa in coastal areas near Admiralty Bay. Most samples were identified using the barcode marker and verified up to the species or genus level with a high degree of similarity. A posterior morphological evaluation focused on samples with novel barcodes allowed for the identification of unknown Austrolecia, Buellia, and Lecidea s.l. species. These results contribute to better represent the lichenized fungi diversity in understudied regions such as Antarctica by increasing the richness of the nucleotide databases. Furthermore, the approach used in this study is valuable for exploratory surveys in understudied regions to guide taxonomic efforts towards species recognition and discovery.

Characterization of major resistance (R) genes to late blight (LB) –caused by the oomycete Phytophthora infestans– is very important for potato breeding. The objective of this study was to identify novel genes for resistance to LB from diploid Solanum tuberosum L. Andigenum Group (StAG) cultivar accessions. Using comparative analysis with a edgeR bioconductor package for differential expression analysis of transcriptomes, two of these accessions with contrasting levels of resistance to LB were analyzed using digital gene expression data. As a result, various differentially expressed genes (P ≤ 0.0001, Log₂FC ≥ 2, FDR < 0.001) were noted. The combination of transcriptomic analysis provided 303 candidate genes that are overexpressed and underexpressed, thereby giving high resistance to LB. The functional analysis showed differential expression of R genes and their corresponding proteins related to disease resistance, NBS-LRR domain proteins, and specific disease resistance proteins. Comparative analysis of specific tissue transcriptomes in resistant and susceptible genotypes can be used for rapidly identifying candidate R genes, thus adding novel genes from diploid StAG cultivar accessions for host plant resistance to P. infestans in potato.

La helada es el estrés abiótico caracterizado por la disminución de la temperatura del aire por debajo de cero grados centígrados, es uno de los problemas de mayor incidencia e impacto en la agricultura andina. Por otro lado, estudios morfológicos y fisiológicos señalan a las papas nativas como fuentes de tolerancia genética al estrés por helada. Sin embargo, las bases moleculares de los mecanismos de tolerancia en papa, aún son desconocidas. La tecnología del secuenciamiento de ARN (RNA-seq) es una excelente herramienta que permite identificar cambios en los perfiles de expresión génica tras el estrés por helada. En este trabajo, el transcriptoma de una variedad de papa tolerante y otra variedad susceptible a helada fueron secuenciados y comparados después de la exposición al estrés por helada (-8 °C) durante una hora, utilizando la técnica del RNA-seq para identificar diferencias en la expresión de genes entre ambas variedades. Se observó que más de 199 millones de lecturas de RNA-seq fueron alineadas al genoma de referencia (Solanum tuberosum Grupo Phureja), lo que corresponde al 82.1% del total de las lecturas obtenidas tras el secuenciamiento. En cuanto a la modulación en la expresión de genes, la variedad tolerante presentó el mayor número de genes expresados diferencialmente (Differentially Expressed Genes, DEGS) sobreexpresados (262 DEGs) y la variedad susceptible presentó el mayor número de DEGs reprimidos (37 DEGs) tras el estrés por helada.