PSI Atlas: a comprehensive knowledgebase of plant self-incompatibility

Self-incompatibility (SI) is an important genetic mechanism in angiosperms that prevents inbreeding and promotes outcrossing. Although significant progress has been made in understanding SI, its molecular underpinnings and evolutionary origins remain elusive in many plant families. In eudicots, SI is typically regulated by a singleS-locus with diverseS-haplotypes, while in grasses, it is controlled by two separateSandZloci. Genome assemblies of SI plants have greatly facilitated the identification and evolutionary analysis ofS-loci. However, a comprehensive database that integrates information on the diverseS-loci has been lacking. To fill this gap, we create the Plant Self-Incompatibility Atlas (PSIA,<ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.plantsi.cn">http://www.plantsi.cn</ext-link>), a knowledgebase that offers an extensive compilation of plant SI, including genomic resources for assembled SI species, the origins and evolution ofSgenes, and the molecular mechanisms of the eight known SI types. In our most recent release, we have obtained more than 500 genome assemblies across 469 SI species. We have also collected 1275 nucleotide and 1130 protein sequence accessions ofSgenes from public databases, with a total of 3095Sgenes manually identified and curated. PSIA not only thoroughly explores theS-locus information of the assembled SI species but also enables users to efficiently browse, perform BLAST searches, analyze, and downloadSgenes. Additionally, PSIA acts as a comprehensive platform for comparative genomic studies ofS-loci, aiding in the exploration of the dynamic processes involved in the origin, loss, and regain of SI. Consequently, PSIA is poised to significantly enhance our understanding of angiosperm SI and offer new perspectives on plant mating systems.