Neonative Diploid-Polyploid Hotspots of Paspalum notatum: Identifying Novel Genetic Diversity for Conservation in South America

Background: Bahiagrass (Paspalum notatum), a key cultivated grass worldwide, includes both sexual diploid and apomictic tetraploid cytotypes. Finding new diploid populations is crucial for the species’ genetic improvement and conservation. Objectives: We aimed to determine the ploidy levels of 168 P. notatum accessions from subtropical South America, analyze the geographic distribution of cytotype diversity, and identify new diploid zones. Methods: Using chromosome counts and flow cytometry, we georeferenced our data with existing literature to map cytotype distribution. Results: We discovered five previously unknown diploid centers in Argentina, Brazil, and Paraguay, two of which resulted from the naturalization of diploid cultivars. One location hosted a mixed-ploidy population (diploid, tetraploid, and pentaploid), confirming ongoing hybridization. Our results show that human activity actively creates new centers of genetic diversity, serving as a dynamic source of raw material for crop resilience. These neonative diversification zones are not only of scientific interest but also vital, evolving hotspots for germplasm conservation. Conclusions: This study presents a new framework for understanding the interactions between crop and wild relatives and highlights the urgent need for conservation in the rapidly changing South American grasslands.