Functional Traits of Olive Varieties and Their Relationship with the Tolerance Level towards Verticillium Wilt

Verticillium wilt of olive (VWO), caused by the soil-borne pathogen Verticillium dahliae, is considered one of the most important diseases affecting this tree crop. One of the best VWO management measures is the use of tolerant cultivars. Remarkably, no information is available about olive functional traits and their potential relationship with tolerance to V. dahliae. Twenty-five selected functional traits (for leaf, stem, root and whole plant) were evaluated in six olive varieties differing in their VWO tolerance level to identify possible links between this phenotype and functional traits’ variation. High intervarietal diversity was found among cultivars and several functional traits were related with VWO tolerance. Tolerant varieties showed higher leaf area, dry matter content (leaf, stem and plant) and mass fraction for stems, but lower for leaves. Significant differences were also detected for root functional traits, tolerant cultivars displaying larger fine root diameter and lignin content but smaller specific length and area of thick and fine roots. Correlations were found among functional traits both within varieties and between levels of tolerance/susceptibility to VWO. Associations were observed between biomass allocation, dry matter content and VWO tolerance. The most relevant difference between tolerant and susceptible cultivars was related to root system architecture.

This work was supported by the Spanish Ministerio de Ciencia e Innovación (grant ECOMEDIT CGL2014-53236-R), Ministerio de Economía, Industria y Competitividad (grant AGL2016-75729-C2-1-R), Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (grant PID2019-106283RB-I00), and by the Junta de Andalucía (Spain) grants ‘For-Change’ (UCOFEDER 18 REF 27943 MOD B) and P18-RT-3455, all of them cofunded with European FEDER funds.