Oak decline: Aerobic bacteria associated with declining Quercus cerris in Central Italy

Abstract

Declining Turkey oaks {Quercus cerris) in Central Italy were studied. Bacteria were isolated from woody tissues between necrotic areas and healthy tissues beneath the bark, from apparently healthy tissues and from exudates oozing from the trunk in spring. A total of 98 bacterial isolates were collected. The determination of the bacteria was by fatty acid profiling and biochemical tests. Erwinia berbicola was frequently found both in necrotic and healthy tissues. Ice-nucleation active species were present. None of the species isolated was considered responsible for the decline.

Bacillus pumilus and Stenotrophomonas maltophilia as two potentially causative agents involved in Persian oak decline in Zagros forests (Iran)

“…In the AOD phenomenon, the mature trees of both Quercus robur and Quercus petraea are affected. Similar symptoms have been reported on a range of native oak species in some European countries, such as Austria (Donaubauer, 1987), Belgium (Vansteenkiste, Tirry, Acker, & Stevens, 2004), Germany (Hartmann & Blank, 1992), Italy (Scortichini, Stead, & Rossi, 1993) and Spain (Biosca et al, 2003). Moreover, larval galleries of the beetle Agrilus biguttatus are usually present weaving a sinuous path along the cambial zone (Denman & Webber, 2009).…”

“…So far, bacterial diseases of oak have not been well studied, probably as their impact on the oak forests has been less important than other factors, and also due to difficulty of identification and characterization of the bacterial causative factors and their mechanisms of action (Kovaleva, Shalovylo, et al, 2015). Previously, a few bacterial pathogens have been reported as causative agents of oak decline (Barnard, Ash, Hopkins, & McGovern, 1998;Brady et al, , 2010Denman et al, 2012;Scortichini et al, 1993) & Denman, 2017;Brady et al, 2012Brady et al, , 2010Broberg et al, 2018;Denman et al, 2012Denman et al, , 2018Denman et al, , 2016Doonan, Denman, Pachebat, & McDonald, 2019;Sapp et al, 2016). These findings show that different bacterial species could play a role in oak decline symptoms development.…”

“…The buprestid A. biguttatus is often found in co-occurrence with various species of bacteria on trees with symptoms of AOD (Denman, Brown, Kirk, Jeger, & Webber, 2014;Denman & Webber, 2009;Gibbs, 1999;Gibbs & Greig, 1997). Similar symptoms have been reported on a range of native oak species in some European countries, such as Austria (Donaubauer, 1987), Belgium (Vansteenkiste, Tirry, Acker, & Stevens, 2004), Germany (Hartmann & Blank, 1992), Italy (Scortichini, Stead, & Rossi, 1993) and Spain (Biosca et al, 2003).…”

Identification and characterization of bacterial strains associated with diseased oak trees in Northern Iran

“…americana , Lonsdalea quercina , Gibbsiella greigii , Rahnella spp. Xylella fastidiosa and Pantoea agglomerans (Barnard, Ash, Hopkins, & McGovern, ; Biosca et al, ; Brady et al, , , , , ; Denman et al, , ; Scortichini, Stead, & Rossi, ). In addition, two Gram‐positive bacteria in the Clostridoides and the genus Carnobacterium were found in oak trees affected with decline in Britain through transcriptomic analyses (Broberg et al, ).…”

“…This fungus is known as one of the most destructive pathogen on oak trees in Iran considering its spatiotemporal distribution and severity of symptoms (Kazempour et al, 2006;Mirabolfathy et al, 2011). Others have reported the oomycete Phytophthora cinnamomi involved in oak and chestnut declines in several regions of the world (e.g., Hardham & Blackman, 2018 (Barnard, Ash, Hopkins, & McGovern, 1998;Biosca et al, 2003;Brady et al, 2012Brady et al, , 2010Brady et al, , 2014aBrady et al, , 2014bBrady et al, , 2014cDenman et al, 2017Denman et al, , 2012Scortichini, Stead, & Rossi, 1993). In addition, two Gram-positive bacteria in the Clostridoides and the genus Carnobacterium were found in oak trees affected with decline in Britain through transcriptomic analyses (Broberg et al, 2018).…”