Susceptible and resistant olive cultivars show differential physiological response to Xylella fastidiosa infections

Abstract

Olive quick decline syndrome (OQDS) is a severe disease, first described in Italy in late 2013, caused by strains of Xylella fastidiosa subsp. pauca (Xfp) in susceptible olive cultivars. Conversely, resistant olive cultivars do not develop OQDS but present scattered branch dieback, which generally does not evolve to severe canopy decline. In the present study, we assessed the physiological responses of Xfp-infected olive trees of susceptible and resistant cultivars. Periodic measurements of stomatal conductance (gs) and stem water potential (Ψstem) were performed using a set of healthy and Xfp-infected plants of the susceptible “Cellina di Nardò” and resistant “Leccino” and “FS17” cultivars. Strong differences in Δgs and ΔΨstem among Xfp-infected trees of these cultivars were found, with higher values in Cellina di Nardò than in Leccino and FS17, while no differences were found among healthy plants of the different cultivars. Both resistant olive cultivars showed lower water stress upon Xfp infections, compared to the susceptible one, suggesting that measurements of gs and Ψstem may represent discriminating parameters to be exploited in screening programs of olive genotypes for resistance to X. fastidiosa.

A Decade after the Outbreak of Xylella fastidiosa subsp. pauca in Apulia (Southern Italy): Methodical Literature Analysis of Research Strategies

“…These authors suggested that narrower vessels limit the spread of the pathogen in the plant, due to a slower flow rate, and that their decreased susceptibility to air embolism leads to less cavitation, which is less beneficial to the bacteria’s aerobic metabolism. Surano et al [ 174 ] investigated the physiological responses of Xfp-infected olive trees in susceptible and resistant varieties. Both resistant olive cvs showed less water stress during Xfp infections than the susceptible one, implying that stomatal conductance and stem water potential measures could be used to discriminate between olive genotypes for resistance to Xfp.…”

European Grapevine Cultivars and Rootstocks Show Differential Resistance to Xylella fastidiosa Subsp. fastidiosa

“…Considering the data presented in this work, several agro-climatic parameters should be tested to enhance breeding programs and establish a discriminative threshold for cultivar selection. At the same time, we should explore new technologies for the early detection of differential physiological responses and phenotyping of foliar disease severity under controlled conditions [68,69].…”

Xylella fastidiosa: A Glimpse of the Portuguese Situation

“…The development of the disease in plants will now primarily depend on the bacteria's ability to move from the point of inoculation and establish a systemic population in the infected plants [3]. After inoculation, the bacterial cells multiply, forming a biofilm [3] composed of bacterial cells, and secrete nucleic acids, proteins, and exopolysaccharides (EPSs) that can completely plug xylem vessels, blocking the transport of water and mineral salts [48].…”

“…Other investigations have been carried out in this context. In 2022, Surano et al used electron microscopy to observe that Leccino olive trees exhibited greater resistance to infection symptoms compared to the Cellina di Nardo variety [48]. According to Petit et al, the symptoms of OQDs varied significantly among olive varieties.…”