Nuclear DNA content estimations in wild olive ( Olea europaea L. ssp. europaea var. sylvestris Brot.) and Portuguese cultivars of O. europaea using flow cytometry

Olive tree (Olea europaea L.) is an economically important woody fruit crop widely distributed in the Mediterranean regions. In this work the genome size of six Portuguese cultivars of olive (O. europaea ssp. europaea var. europaea) and wild olive (O. europaea spp. europaea var. sylvestris) was estimated for the first time. The nuclear DNA content of O. europaea cultivars ranged between 2.90 ± 0.020 pg/2C and 3.07 ± 0.018 pg/2C and the genome size of wild olive was estimated as 3.19 ± 0.047 pg/2C DNA. These results suggest a low intraspecific variation at least among the studied cultivars and between them and wild olive. This is not in accordance with previous results in some Italian cultivars where high genome size heterogeneity was found. The methodology presented here seems appropriate for genome size estimations within this genus and opens good perspectives for a large screening of estimation of nuclear DNA content among O. europaea cultivars and Olea species that could clarify this issue.