Olive, the emblematic Mediterranean fruit crop, owns a great varietal diversity, which is maintained in ex situ field collections, such as the World Olive Germplasm Bank of Córdoba (WOGBC), Spain. Accurate identification of WOGBC, one of the world’s largest collections, is essential for efficient management and use of olive germplasm. The present study is the first report of the use of a core set of 96 EST-SNP markers for the fingerprinting of 1273 accessions from 29 countries, including both field and new acquired accessions. The EST-SNP fingerprinting made possible the accurate identification of 668 different genotypes, including 148 detected among the new acquired accessions. Despite the overall high genetic diversity found at WOGBC, the EST-SNPs also revealed the presence of remarkable redundant germplasm mostly represented by synonymy cases within and between countries. This finding, together with the presence of homonymy cases, may reflect a continuous interchange of olive cultivars, as well as a common and general approach for their naming. The structure analysis revealed a certain geographic clustering of the analysed germplasm. The EST-SNP panel under study provides a powerful and accurate genotyping tool, allowing for the foundation of a common strategy for efficient safeguarding and management of olive genetic resources.

Regulated deficit irrigation in super-high-density (SHD) olive orchards is a well-known strategy to save water and control plant vigor, without decreasing fruit or oil yield. As there is controversial information about its influence on virgin olive oil quality, a trial was conducted in five SHD olive orchards of Arbequina cultivar in different locations of central, east, north and northeast Spain under full irrigation (FI) and regulated deficit irrigation (RDI) treatments. RDI applied during phase II of fruit growing (40% of total needs) saves more than 20% of water on average, without reductions in olive fruit or extra virgin olive oil (EVOO) yield. No threshold of 3.5 MPa of stem water potential was crossed in any case. RDI modified sterols and the fatty acid profile of EVOOs but not phenols, quality parameters, or the sensory profile. Latitude, altitude, and yearly rainfall have a big impact on some compounds such as campesterol, oleuropein, or margaroleic or linolenic acids.

Studies of the virome of olive trees with symptoms of leaf mottling by high-throughput sequencing (HTS) revealed the presence of a new virus. Full coding genome sequences of two isolates were determined and consisted of a single RNA segment of 16,516 nt and 16,489, respectively. The genomic organization contained 10 open reading frames (ORFs) from 5′ to 3′: ORF1a, ORF1b (RdRp), ORF2 (p22), ORF3 (p7), ORF4 (HSP70h), ORF5 (HSP90h), ORF6 (CP), ORF7 (p19), ORF8 (p12), ORF9 (p23) and ORF10 (p9). Phylogenetic analyses clustered this virus in the genus Olivavirus, family Closteroviridae, with the closest species being Olivavirus flaviolae, commonly named olive leaf yellowing-associated virus (OLYaV). However, amino acid sequences of all taxonomically relevant proteins showed, in all cases, a divergence higher than 25% between OLYaV and the new virus, indicating that it represents a new species in the genus Olivavirus for which the common name of olive leaf mottling virus (OLMV) is proposed. This study represents an advance in the genus Olivavirus and provides new insights into the olive virome.

Aim of the study: The nowadays avocado cropping world burst confronts water quality constraints as it unfolds throughout semi-arid climates. Therefore, many salt-tolerant rootstocks have been developed, with those from the West Indian avocado subspecies such as ‘Nachar’ standing out. However, the salt-tolerance of ‘Nachar’ had not been characterized and this study fills this knowledge gap. Area of study: Accordingly, an open-air trial was performed in Moncada (València). Material and methods: ‘Nachar’ seedling rootstocks grafted with ‘Hass’ avocado were irrigated with five nutritive solutions differing in chloride (Cl-), but with low sodium (Na+) adsorption ratio (SAR). Plant development and leaf nutrient status, including Cl- and Na+, were monitored, and the ‘Nachar’ salt-tolerance was characterized based on the accumulation rates of leaf Cl- and Na+ as a function of, respectively, Cl- and SAR in the irrigation water. These parameters are seldom expressly assessed but are argued here as providing better insight into the actual Cl- and Na+ exclusion ability of rootstocks than the usual maximum permissible, —to avoid leaf injury— leaf Cl- and Na+. Main results: The ‘Nachar’ was found to rank high and very high in, respectively, Cl- and Na+ exclusion ability, when compared to other avocado rootstocks. However, more salt-driven leaf injuries and potential yield losses would still be expected in avocado grafted onto the ‘Nachar’ in comparison to other salt-sensitive woody crops. Research highlights: The ‘Nachar’ seems an interesting starting point in further rootstock improvement for salt-tolerance in avocado. However, if unproperly carried out, the propagation of salt-tolerant avocado rootstocks such as ‘Nachar’ and others may also result in the loss of the previously achievements of salt-tolerance.