Alternative Evolutionary Pathways in Paspalum Involving Allotetraploidy, Sexuality, and Varied Mating Systems

The genetic systems of Paspalum species have not been extensively studied. We analysed the ploidy, reproductive mode, mating system, and fertility of four Paspalum species - P. durifolium, P. ionan-thum, P. regnellii, and P. urvillei. An analysis of 378 individuals from 20 populations of north-eastern Argentina was conducted. All populations of the four Paspalum species were pure tetraploid and had a sexual and stable reproductive mode. However, some populations of P. durifolium and P. ionanthum showed low levels of apospory. Populations of P. durifolium and P. ionanthum had low seed sets under self-pollination but were fertile under open pollination, showing that self-incompatibility likely caused self-sterility. In contrast, populations of P. regnellii or P. urvillei showed no evidence of apospory and seed set in both self- and open pollination conditions were high, suggesting that they are self-compatible, due to the absence of pollen-pistil molecular in-compatibility mechanisms. The evolutionary origin of the four Paspalum species could explain these differences. This study supplies valuable insights into the genetic systems of Paspalum species, which could have implications for their conservation and management.