The endosperm balance number (EBN) theory states that genomic contribution ratio should be kept at 2:1 maternal/paternal (m:p) ratio for normal endosperm development. However, the endosperm formation in apomictic Paspalum notatum Flüggé does not depend on the EBN. The aim of this work was to characterize gene expression during seed formation from apomictic and sexual P. notatum using complementary DNA‐amplified fragment length polymorphism methodology. To induce the formation of seeds with different m:p genomic ratios, crosses were made between genotypes with different ploidy levels and reproductive modes. RNA was isolated from ovaries 24 h after pollination, when maximum endosperm growth rate was expected. Some of the 49 differentially expressed transcript‐derived fragments (DETDFs) provided relevant information. Three of those were found in ovaries of apomictic plants with an EBN different from 2:1. A DETDF was predicted to be involved in sucrose metabolism during the accumulation of hexose and starch in the endosperm and might be related to EBN insensitivity. Twenty‐two DETDFs were found in crosses where sexual plants were used as the female parent and the predicted m:p ratio was not 2:1. One of those was related to the failure of fusion of the polar nuclei in Arabidopsis thaliana (L.) Heynh. Finally, three transcripts presented similarity with a casein kinase II that regulates the accumulation of storage products in seeds of A. thaliana. Both processes might be involved in endosperm development in P. notatum.

In natural ecosystems, plants appear to be in symbiosis with diverse fungal endophytes which can have impacts on plant communities. Paspalum is one of the most important grass genera in South American grasslands. The aim of this work was to determine the presence of fungal endophytes in two Paspalum species and evaluate their effects on plant growth. Sixty plant samples were collected for Paspalum notatum in a rangeland in northeastern Argentina, and the same number for Paspalum dilatatum in central Argentina. A triple‐sterilization process was carried out by submerging small pieces of leaves and stems for the isolation of fungi from the collected plants. In order to identify endophytes, morphological characters and fungal sequences corresponding to the ITS (Internal Transcribed Spacer) region were analysed. A total of eight genera were identified: Acremonium, Alternaria, Aspergillus, Bipolaris, Cladosporium, Fusarium, Penicillium and Trichoderma. A greenhouse trial was conducted to determine the effects of fungal endophytes on growth. Trichoderma significantly increased relative chlorophyll content in P. notatum and Acremonium endophytes increased tiller number, and above‐ and below‐ground biomass in P. dilatatum. The diversity of fungal endophytes that was present in P. notatum and P. dilatatum was described. In conclusion, some aspects of growth of these Paspalum species seem to be positively affected by Trichoderma and Acremonium.