Evaluation of the Phytopathological Reaction of Wild and Cultivated Olives as a Means of Finding Promising New Sources of Genetic Diversity for Resistance to Root-Knot Nematodes

Abstract

Olive (Olea europaea L.) is one of the most important fruit crops in the Mediterranean Basin, because it occupies significant acreage in these countries and often has important cultural heritage and landscape value. This crop can be infected by several Meloidogyne species (M. javanica, M. arenaria, and M. incognita, among others), and only a few cultivars with some level of resistance to these nematodes have been found. Innovations in intensive olive growing using high planting densities, irrigation, and substantial amounts of fertilizers could increase the nematode population to further damaging levels. To further understand the interactions involved between olive and pathogenic nematodes and in the hope of finding solutions to the agricultural risks, this research aimed to determine the reaction of important olive cultivars in Spain and wild olives to M. javanica infection, including genotypes of the same and other O. europaea subspecies. All olive cultivars tested were good hosts for M. javanica, but high levels of nematode reproduction found in three cultivars (Gordal Sevillana, Hojiblanca, and Manzanilla de Sevilla) were substantially different. In the wild accessions, O. europaea subsp. cerasiformis (genotype W147) and O. europaea subsp. europaea var. sylvestris (genotype W224) were resistant to M. javanica at different levels, with strong resistance in W147 (reproduction factor [Rf] = 0.0003) and moderate resistance in W224 (Rf = 0.79). The defense reaction of W147 to M. javanica showed a strong increase of phenolic compounds but no hypersensitive reaction.

Accessing Ancestral Origin and Diversity Evolution by Net Divergence of an Ongoing Domestication Mediterranean Olive Tree Variety

“…Corroborating this hypothesis, the ‘Galega vulgar’ from WOGB in the work of Díez et al ( 2015 ), analyzing a data set of wild and cultivated olive trees with SSRs to estimate its most probable demographic model, belongs to a Central cluster that shows signs of a mixture between cultivated and wild olives. So, it is possible that ‘Galega vulgar’ still holds undomesticated forms, which might be beneficial for the selection of interesting phenotypes [such as resistant traits studied by Jiménez-Fernández et al ( 2016 ) and Palomares-Rius et al ( 2019 ) in wild olive trees] in breeding programs. As shown in Lazović et al ( 2018 ), several east Adriatic olive tree varieties revealed many differences in their intra-varietal diversity.…”

The Status of Genetic Resources and Olive Breeding in Tunisia

“…Wild olive forests are native to Tunisia and wild/feral olive forms can be found in natural and agrarian ecosystems [65]. This germplasm appears promising for resistance to defoliating Verticillium [85] and root-knot nematodes [86], as well as drought tolerance [87]. In addition, it is considered a resource for improving olive oil's quality.…”

Genetic and physiological characterization of sunflower resistance provided by the wild-derived OrDeb2 gene against highly virulent races of Orobanche cumana Wallr

“…The sections were obtained with a rotary microtome at 8 μm and immediately attached to adhesive-treated glass slides. After removal of paraffin, the sections were stained with a combination of tannic acid-ferric chloride, safranin, and fast green, by which nuclei, chromosomes, and lignified or suberized cell walls stain red, cytoplasm and cellulosic cell walls stain green, and the tannic acid-iron chloride aids in cell wall definition and is considered to be a general test for phenols (Jensen 1962;Reeve 1951;Ruzin 1999;Palomares-Rius et al 2019). The stained tissue was evaluated under a light microscope to observe the process of parasitic invasion into sunflower tissues.…”