Biology subjects

Gonzalez, L. N.

Publications and source records attributed to Gonzalez, L. N..

4 recordsLinked to original sources

bioRxiv2025

Microscopical and molecular characterization of the infection cycle of Phytophthora betacei during disease development on tree tomato (Solanum betaceum).

Phytophthora betacei is a recently described oomycete plant pathogen closely related to Phytophthora infestans sensu stricto. This plant pathogen naturally infects tree tomato (Solanum betaceum) but has not been reported on tomatoes and potatoes, the primary hosts of P. infestans. The aim of this study was to characterize the infection cycle of P. betacei using microscopy and molecular approaches. Several strains were inoculated in susceptible tree tomato plants and disease progression was monitored via six epidemiological parameters. Although different P. betacei strains displayed a highly variable disease phenotype, the most aggressive one was chosen for further plant inoculations. Samples at different time points of the infection cycle were analyzed at the cellular level via light and scanning electron microscopy (SEM) and at the molecular level via qRT-PCR of infection-stage-specific markers. The infection cycle of P. betacei differed from that of P. infestans in having a longer biotrophic stage, larger lesions, and higher sporulation capacity. Additionally, P. betacei transcriptomic profiles were monitored along the infection cycle via RNAseq and evidenced a changing expression landscape that supports an elongated hemibiotrophic transition and a clear distinction from what is being expressed in the mycelium or the sporangia. This study provides novel insights into the interaction between P. betacei and S. betaceum.

plant biology↗

bioRxiv2024

Contribution of the epididymis beyond fertilization: relevance of CRISP1 and CRISP3 for sperm DNA integrity and early embryo development

Numerous reports show that the epididymis plays a key role in the acquisition of sperm fertilizing ability but less information exists on its contribution to embryo development. Evidence from our laboratory showed that mammalian CRISP (Cysteine-Rich Secretory Proteins), known to be expressed in the epididymis, to regulate calcium (Ca2+) channels and to participate in fertilization, may also be relevant for embryo development. More specifically, we found that males with simultaneous mutations in Crisp1 and Crisp3 genes exhibited normal in vivo fertilization but impaired embryo development. In the present work, aimed to investigate the mechanisms underlying this reproductive phenotype, we observed that embryo development failure was not due to delayed fertilization as no differences in sperm transport within the female tract nor in in vivo fertilization were found shortly after mating. The observation that impaired embryo development was also found in eggs fertilized by epididymal sperm either after uterine insemination or in vitro fertilization, revealed that the defects were already present at epididymal level. Of note, eggs fertilized in vitro by mutant sperm exhibited impaired meiotic resumption not due to defects in Ca2+oscillations during egg activation, prompting us to examine potential sperm DNA defects. Interestingly, DNA fragmentation was found in cauda but not caput epididymal mutant sperm revealing that DNA integrity defects appear during epididymal maturation. Moreover, exposure of control sperm to mutant epididymal fluid significantly increased DNA fragmentation, indicating the relevance of the luminal environment for sperm DNA integrity. The finding that incubation of sperm with control epididymal fluid in the presence of Ca2+ also increased DNA fragmentation together with the higher intracellular Ca2+ levels detected in mutant sperm supports a dysregulation of Ca2+ homeostasis as the main responsible for DNA fragmentation and subsequent early development failure of mutant males. Together, our results support the contribution of the epididymis beyond fertilization, identifying CRISP1 and CRISP3 as novel male factors relevant for DNA integrity and early embryo development. Given the existence of human functional homologues of CRISP and the incidence of DNA fragmentation in infertile men, we believe these findings not only provide relevant information on the impact of epididymal factors on embryonic development but will also contribute to a better understanding, diagnosis and treatment of human infertility.

developmental biology↗

bioRxiv2021

Evaluation of small non-coding RNAs as a possible epigenetic mechanism mediating the transition from biotrophy to necrotrophy in the life cycle of Phytophthora infestans

Phytophthora infestans, causal agent of late blight disease of potatoes, causes billion-dollar losses worldwide each year. This plant pathogen is a hemibiotroph, first feeding on the host and later killing it. Even though the transcription dynamics of this transition are characterized, the role that small non-coding RNAs (sRNAs) might have is still unknown. Furthermore, a bioinformatic pipeline to search and analyze sRNAs in P. infestans, is needed. Using our proposed pipeline, 146 sRNAs were found to be significantly differentially expressed between the evaluated stages of the pathogens life cycle. One hundred of these sRNAs were successfully annotated and classified into nine functional categories. The expression of the genes associated to ten of these sRNAs was validated via qRT-PCR. Among these, the expression levels of genes encoding for effectors were inversely correlated to that of the sRNAs aligning to them, which is expected if sRNAs are indeed regulating their expression. This correlation was not clear for sRNAs in other functional categories and should not be confused with strict causality. This study works as a starting point for considering sRNAs as role players in the transition from biotrophy to necrotrophy in P. infestans when infecting Solanum tuberosum.

microbiology↗

bioRxiv2016

Ecological speciation within the Phytophthora group

Over the past few years, symptoms akin to late blight disease have been reported on a variety of crop plants in South America. Despite the economic importance of these crops, the causal agents of the diseases belonging to the genus Phytophthora have not been completely characterized. In this study, we used an integrative approach that leveraged morphological, ecological, and genetic approaches to explore cryptic speciation within P. infestans sensu lato. We described a new Phytophthora species collected in Colombia from tree tomato (Solanum betaceum), a semi-domesticated fruit. All morphological traits and population genetic analyses, using microsatellite data and a reduced representation of single nucleotide polymorphism (SNP) data, support the description of the new species, Phytophthora betacei sp. nov. We have demonstrated that ecological differences are important in the persistence of P. infestans and P. betacei as genetically isolated units across an overlapping area in the northern Andes.

evolutionary biology↗