Biology subjects

Bente, H.

Publications and source records attributed to Bente, H..

4 recordsLinked to original sources

bioRxiv2025

AGO5 restricts virus vertical transmission in plant gametophytes

The propagation of a viral infection from a host parent to its progeny is known as vertical transmission, or seed transmission in plants. It allows viral infections to rapidly spread locally via pollen and worldwide through seeds. To be vertically transmitted to each progeny, a virus must pass through the tight bottleneck of at least one cell per parent - the gametes. Therefore, stopping infection during sexual reproduction is of vital importance to generate healthy offspring. Accordingly, vertical transmission of plant viruses often occurs at very low rates, if at all, suggesting the existence of highly effective - yet unknown - antiviral defenses in pre-meiotic cells, gametes and/or embryos. In this study, we show that AGO5, an RNA interference factor expressed specifically in shoot apical meristem stem cells and the germline of Arabidopsis thaliana, drastically reduces the vertical transmission of Turnip yellow mosaic virus (TYMV). Through a series of controlled pollination experiments leveraging different zygosity of ago5 knock-out, cell type-specific rescue of ago5 and TYMV detection in whole-mount reproductive tissues, we provide evidence that AGO5 acts in pollen and sperm cells to restrict virus transmission to progeny. We further show that triggering antiviral RNA interference specifically in sperm cells leads to a significant reduction in TYMV vertical transmission. In summary, this study provides the first description of a gamete-specific antiviral defense mechanism restricting virus vertical transmission, paving the way for new strategies to prevent the spread of pollen- and seed-borne viral epidemics.

plant biology↗

bioRxiv2025

Samplify: A versatile tool for image-based segmentation and annotation of seed abortion phenotypes

Automated seed phenotyping has wide applications in research and agriculture and relies on easy-to-use platforms and pipelines. Seed phenotyping in the model species Arabidopsis thaliana poses a significant challenge due to the large number of tiny seeds produced by individual plants, which are difficult to manually separate and count. Manual counting methods are time-consuming and prone to user bias, particularly for subtle phenotypic changes. To address these limitations, we developed Samplify, a scalable, automated pipeline for seed segmentation and classification. By integrating classical image processing techniques with Metas Segment Anything Model (SAM), Samplify effectively segments Arabidopsis seeds, even in dense clusters where conventional methods fail. To demonstrate its versatility, we quantified the seed abortion occurring in interploidy crossings in Arabidopsis, often referred to as triploid block. Samplify includes a Random Forest classifier trained on a set of computed seed shape features that enables the categorization of seeds into normal, partially aborted, and fully aborted seeds, automating the manual classification process. The tool, designed as a command-line application, significantly reduces manual annotation workload. Our validation across multiple datasets demonstrates high segmentation and classification reliability, making Samplify a valuable resource for the plant research community.

plant biology↗

bioRxiv2022

Two AGO proteins with transposon-derived sRNA cargo mark the germline in Arabidopsis

Summary paragraphIn sexually propagating organisms, genetic and epigenetic mutations are evolutionarily relevant only if they occur in the germline and provide inherited information to the next generation. In contrast to most animals, plants are thought to lack an early segregating germline, implying that somatic cells can contribute genetic information to the progeny. Here we demonstrate that two ARGONAUTE proteins, AGO5 and AGO9, mark an early-segregating germline. Both AGOs are loaded with dynamically changing populations of small RNAs derived from highly methylated, pericentromeric, long transposons. Sequencing single nuclei revealed that many of these transposons are co-expressed within an AGO5/9 expression domain of the shoot apical meristem (SAM). This indicates a host-parasite tug of war and specific silencing pathways along the plant germline throughout development. Our results open the path to investigate transposon biology and epigenome dynamics at cellular resolution in the SAM stem cell niche.

plant biology↗

bioRxiv2020

Polyploidy-associated paramutation in Arabidopsis is determined by small RNAs, temperature, and structure

Paramutation is a form of non-Mendelian inheritance in which the expression of a paramutable allele changes when it encounters a paramutagenic allele. This change in expression of the paramutable alleles is stably inherited even after segregation of both alleles. While the discovery of paramutation and studies of its underlying mechanism were made with alleles that change plant pigmentation, paramutation-like phenomena are known to modulate the expression of other traits and in other eukaryotes, and many cases have probably gone undetected. It is likely that epigenetic mechanisms are responsible for the phenomenon, as paramutation forms epialleles, genes with identical sequences but different expression states. This could account for the intergenerational inheritance of the paramutated allele, providing profound evidence that triggered epigenetic changes can be maintained over generations. Here, we use a case of paramutation that affects a transgenic selection reporter gene in tetraploid Arabidopsis thaliana. Our data suggest that different types of small RNA are derived from paramutable and paramutagenic epialleles. In addition, deletion of a repeat within the epiallele changes its paramutability. Further, the temperature during the growth of the epiallelic hybrids determines the degree and timing of the allelic interaction. The data further make it plausible why paramutation in this system becomes evident only in the segregating F2 population of tetraploid plants containing both epialleles. In summary, the results support a model for polyploidy-associated paramutation, with similarities as well as distinctions from other cases of paramutation. AUTHOR SUMMARYIn 1866, Gregor Mendel formulated the general principles of inheritance based on crossing experiments with pea plants. Curiously, in 1915, the progeny from crossing pea plants with a regular and a "rogue" leaf phenotype was lacking the expected segregation and recovery of the regular phenotype. This discovery was one of the first observations of non-Mendelian genetics and later demonstrated for more traits in other plants and termed paramutation. Paramutation is due to the epigenetic switch of an active gene to a silenced version which is then maintained in the inactive state in later generations. This demonstrates that acquired epigenetic changes can become permanent. Despite its early observation and numerous studies, mainly in maize and tomato, it is barely understood how paramutation is established and which parameters influence the process. We investigated a case of paramutation in Arabidopsis thaliana, crossing plants with genetically identical but epigenetically different alleles that result in resistance or sensitivity to an antibiotic in the growth medium. Paramutation did not become manifest immediately but only in the progeny of the hybrids, and only in plants with a doubled chromosome set. These features make this paramutation distinct from other cases. Our studies revealed several parameters that influence paramutation: an important role for sRNAs to initiate silencing, the sequence of the allele itself, the environmental conditions during growth of the hybrids, the developmental stage, and the copy number ratio between the alleles.

genetics↗