Pollination type modulates residual sexuality in apomictic Paspalum rufum

Abstract

ABSTRACT Paspalum rufum Nees is a subtropical species that presents diploid individuals that primarily reproduce sexually and through allogamy due to self-incompatibility, as well as tetraploid races that are self-fertile and reproduce via apomixis. Embryological studies have shown that tetraploid races can occasionally produce offspring through sexual reproduction, making them facultative apomicts. This study aimed to analyze the impact of pollen source on the rate of apomixis in facultative apomictic accessions of P. rufum. Six progenies were obtained through self-pollination and cross-pollination from three facultative apomictic tetraploid (4×) genotypes of P. rufum: Q3756, Q3785, and Q4185. The progeny origin, whether maternal or non-maternal, was determined using molecular markers. Our findings indicate that the pollen source significantly influenced the progeny origin across three P. rufum accessions. In instances of self-pollination by a facultative apomictic plant, most of its descendants originate from aposporous embryo sacs (AES) and are genetically identical to the mother plant, with the percentage of non-maternal plants ranging from 1 % to 6 %. However, when the same genotype undergoes cross-pollination, the percentage of non-maternal offspring can rise to 19 % in the progeny derived from the Q4185 × Q3785 cross. This residual sexuality and the manipulation of pollination conditions could be effective strategies for generating genetic variability in apomictic species for which fully sexual counterparts are not available.