Assessment of Pierce's disease susceptibility in Vitis vinifera cultivars with different pedigrees

Abstract

Pierce's disease (PD) of grapevine is caused by the bacterium Xylella fastidiosa. In this study, an integrated approach was applied to assess PD susceptibility among different Vitis vinifera cultivars that incorporated disease severity, bacterial pathogen abundance and loss of stem xylem hydraulic conductivity. It was hypothesized that levels of PD susceptibility in V. vinifera can be attributed in part to the host anatomical features that are shaped by its pedigree background. Two popular wine grape cultivars were initially selected from the occidentalis group, Merlot and Cabernet Sauvignon, and one from the orientalis group, Thompson Seedless. The more recently bred table grape cultivar Scarlet Royal, that has mixed pedigree parentage, was also included. PD susceptibility was compared to the known PD resistant b43-17 V. arizonica/ candicans wild grape species from North America. The data indicated that Thompson Seedless was ranked as the most susceptible to PD because it significantly exhibited the most severe disease symptoms at 12 weeks post-inoculation and hosted the highest X. fastidiosa titre of the cultivars, and lost over 90% of its stem hydraulic conductivity. In contrast, the other three cultivars displayed less susceptibility to PD. The way in which the xylem anatomy could impact PD susceptibility in V. vinifera cultivars is discussed, together with how grape pedigrees and their cognate centre of domestication may have influenced xylem anatomical features. This work provides a reference framework to further test the hypothesis that V. vinifera cultivars with wide xylem vessels may be more prone to PD decline.

Differences in the Endophytic Microbiome of Olive Cultivars Infected by Xylella fastidiosa across Seasons

“…Indeed, Xylella colonization is significantly more extensive in Kalamata than FS17, which confirms, together with the limitedness of symptoms, the traits of resistance identified in the latter cultivar. Altogether, these results suggest that other mechanisms, likely controlling Xylella population size and its pathogenic effects by genetic [ 13 ] or anatomic [ 7 ] traits, may be responsible for this phenotype.…”

“…The ability to infect up to 595 plant species [ 5 ], together with the insect transmission [ 6 ] and the lack of effective treatments to cure infected plants [ 2 ], make the control of Xylella infections very challenging, requiring a compendium of integrated strategies relying on reducing vector population, eliminating sources of infections, and search for resistance traits in the affected species. Proofs of genetic resistance have been found in grape [ 7 , 8 ] and citrus [ 9 , 10 , 11 , 12 ] and more recently in olive cultivars Leccino and FS17 [ 13 , 14 , 15 , 16 , 17 ]. Even so, mechanisms underlying differential host responses to Xylella infections are still largely unknown.…”

“…While genetic [ 8 , 20 ] and/or anatomo-physiological [ 7 , 21 ] studies have contributed to unravel some of the mechanisms that contribute to constraining Xylella multiplication and movement in resistant grapevines, very little is known about the relationships of X. fastidiosa with all other microorganisms inhabiting the xylem vessels and their potential role in limiting infections, i.e., contributing to modulate the response in resistant phenotypes. In this framework, we studied the dynamics of Xylella plant colonization in relation to the whole olive microbiome to shed light on the complex network of interactions occurring among microorganisms inhabiting the same niche, the xylem vessels.…”

Seasonal and long-term consequences of esca on grapevine stem xylem integrity

“…This is the case regarding the susceptibility of different species or varieties to specific pathogens (Jacobi & MacDonald, 1980;Ouellette et al, 1999;Clerivet et al, 2000;Et-Touil et al, 2005;Venturas et al, 2014;Park & Juzwik 2014;Rioux et al, 2018), in particular to Phaeomoniella chlamydospora, one of the pathogen associated with esca (Pouzoulet et al, 2017;. (ii) In other studies, it has been shown that tyloses can exacerbate symptoms (Talboys, 1972): they cause a reduction in stem hydraulic conductivity, sometimes associated with a reduction in stomatal conductance in leaves and, in the most severe cases, wilting (Parke et al, 2007;Beier et al, 2017;Lachenbruch & Zhao, 2019, Mensah et al, 2020Sun et al, 2013;Deyett et al, 2019 during Pierce's disease). Our results suggest that during esca (i) the development of tyloses in stems cannot be interpreted as a systematic trait of pathogen resistance because visual symptoms were observed despite the presence of tyloses and they were produced at a distance from pathogens.…”

Behind the curtain of the compartmentalization process: Exploring how xylem vessel diameter impacts vascular pathogen resistance

“…As these pathogens colonize the vascular system, the xylem conductivity of the host progressively decreases due to the occlusion of vessels by tyloses and gels triggered by the host in order to compartmentalize the infection (Pearce, 1996;Yadeta & Thomma, 2013). This loss of hydraulic conductivity has negative effects on the plant and according to the extent of infection can ultimately lead to plant death (Deyett et al, 2019;Inch & Ploetz, 2012).…”