VPS13 has an important role in female germline development in Arabidopsis

The female germline precursor cell, known as the megaspore mother cell (MMC), differentiates and develops within the ovule through a complex genetic network, including post-transcriptional and translational regulation mediated by miRNA. A key player in restricting MMC development to a single cell within the nucellus is the AUXIN RESPONSE FACTOR 3 (ARF3). Here, we describe the role of the VACUOLAR PROTEIN SORTING-ASSOCIATED 13 (VPS13) in post-transcriptional regulation of ARF3. VPS13 is a conserved protein found across all eukaryotes, implicated in membrane dynamics, organelle junctions, and autophagy. We show that in Arabidopsis, the knockout mutation of VPS13 results in the deregulation of ARF3, most likely due to a reduction of tasiR-ARF production. Consequently, vps13 mutant ovules exhibit phenotypes similar to those caused by ARF3 misregulation, such as the formation of multiple MMC-like cells and defects in megasporogenesis. VPS13 co-localizes and interacts with the SUPPRESSOR OF GENE SILENCING 3 (SGS3). Based on our findings, we propose an uncharacterized potential role for VPS13 in the homeostasis of membrane-associated siRNA bodies, essential for tasiR-ARF biogenesis. Thus, it adds an additional component to the intricate network governing female germline initiation and progression, while also providing new insights into siRNA body homeostasis and tasiR-ARF pathways. Furthermore, the evolutionary conservation of VPS13 suggests its broader relevance, potentially extending to the understanding of human diseases linked to mutations in its orthologues.