Biology subjects

Annacondia, M. L.

Publications and source records attributed to Annacondia, M. L..

4 recordsLinked to original sources

bioRxiv2023

Hop stunt viroid infection alters host heterochromatin

Viroids are pathogenic non-coding RNAs that completely rely on their host molecular machinery to accomplish their life cycle. Several interactions between viroids and their host molecular machinery have been identified, including an interference with epigenetic mechanisms such as DNA methylation. Despite this, whether viroids influence changes in other epigenetic marks such as histone modifications remained unknown. Epigenetic regulation is particularly important during pathogenesis processes because it might be a key regulator of the dynamism of the defense response. Here we have analyzed the changes taking place in Cucumis sativus facultative and constitutive heterochromatin during hop stunt viroid (HSVd) infection using chromatin immunoprecipitation (ChIP) of the two main heterochromatic marks: H3K9me2 and H3K27me3. We find that HSVd infection is associated with changes in both H3K27me3 and H3K9me2, with a tendency to decrease the levels of repressive epigenetic marks through infection progression. These epigenetic changes are connected to the transcriptional regulation of their expected targets, genes and transposable elements. Indeed, several genes related to the defense response are targets of both epigenetic marks. Our results highlight another host regulatory mechanism affected by viroid infection, providing further information about the complexity of the multiple layers of interactions between pathogens/viroids and hosts/plants.

plant biology↗

bioRxiv2023

Heterochromatin re-organization associated with the transcriptional reprogramming under viral infection in Arabidopsis

Epigenetic mechanisms are key regulators of genomic integrity and genic expression. Emerging evidence shows that epigenetic regulation is an important component of the transcriptional reprogramming during stress. Despite this, the overall stress-induced reprogramming of the different epigenetic marks and their targets are unknown. Here, we uncovered multiple epigenetic changes taking place during viral infection in Arabidopsis thaliana and their connection with gene expression. We find that cucumber mosaic virus (CMV) infection induces an overall reorganization of the repressive epigenetic marks H3K9me2, H3K27me3, and DNA methylation, which interact between them and are dynamic during infection. Overall, these epigenetic changes are involved in the reprogramming of the transcriptional program to adapt to the biotic stress, and might ensure genome stability through the transcriptional control of transposable elements (TEs). Mechanistically, we demonstrate that the catalytic component of the Polycomb Repressive Complex 2 (PRC2) CURLY LEAF (CLF) mediates the transcriptional repression of genes gaining H3K27me3 during viral infection and that mutants on that component induce resistance against CMV. Altogether, our results provide a complete picture of the epigenetic changes that occur during biotic stress and exemplify the overall dynamism of epigenetic regulation in eukaryotic organisms.

plant biology↗

bioRxiv2020

Aphid feeding induces the relaxation of epigenetic control and the associated regulation of the defense response in Arabidopsis

Environmentally induced changes in the epigenome help individuals to quickly adapt to fluctuations in the conditions of their habitats. Here we explored those changes in Arabidopsis thaliana plants subjected to multiple biotic and abiotic stresses, and identified transposable element (TE) activation in plants infested with the green peach aphid, Myzus persicae. We performed a genome-wide analysis of DNA methylation, mRNA expression, mRNA degradation and small RNA accumulation. Our results demonstrate that aphid feeding induces loss of methylation of hundreds of loci, mainly TEs. This loss of methylation has the potential to regulate gene expression and we found evidence that it is involved in the control of key plant immunity genes. Accordingly, we find that mutant plants deficient in epigenetic silencing show increased resistance to M.persicae infestation. Collectively, our results show that changes in DNA methylation play a significant role in the regulation of the plant transcriptional response and induction of defense response against aphid feeding.

plant biology↗

bioRxiv2019

MicroRNA function transitions from regulating developmental genes to transposable elements during the maturation of pollen

microRNAs play important roles to control the development of eukaryotic organisms. Both animal and plant microRNAs are essential for the spatio-temporal regulation of development but together with this role, plant microRNAs also control transposable elements and stimulate the production of epigenetically-active small interfering RNAs. This last role is evident in the plant male gamete containing structure, the male gametophyte or pollen grain, but how the dual role of plant microRNAs is integrated during its development is unknown. Here, we provide a detailed analysis of microRNA dynamics during pollen development and their genic and transposable element targets using small RNA and mRNA cleavage (PARE) high-throughput sequencing. Furthermore we uncover the microRNAs loaded in the two main Argonaute proteins in the mature pollen grain, AGO1 and AGO5. Our results indicate that the developmental progression from microspore to mature pollen grain is characterized by a reprogramming from microRNAs focused on the control of development to microRNAs regulating transposable element control.

plant biology↗