Isolation and identification of Rahnella victoriana associated with bacterial canker of Eucalyptus in Iran

Abstract

Eucalypts are cultivated in many regions of the world because of their amenability to intensive plantation forestry (environmental adaptability and plasticity of clones, fast growth, easiness of rooting and strong re‐sprouting after coppicing), quality of the timber for multiple uses and high economic performance. Symptomatic Eucalyptus camaldulensis trees were sampled at two sites in the Mazandaran province of Iran. Plants showed trunk bark cracking and cankers accompanied by dark‐brown watery exudation from damaged tissues. Isolation, purification along with phenotypic and genotypic characterization of isolates were performed using routine bacteriological methods. Finally, the bacterial isolates obtained from cankers on symptomatic eucalyptus plants were identified as Rahnella victoriana based on results of biochemical tests in combination with analyses of partial sequences of the 16S rRNA, gyrB,rpoB, and atpD gene regions. When representative isolates were inoculated into the stem of 1‐year‐old E. camaldulensis saplings, necrotic lesions were visible in external and internal bark tissues 30 days after inoculation. The bacteria were re‐isolated from lesions up to 2 months post‐inoculation. This is the first report of bacterial canker of Eucalyptus caused by R. victoriana in Iran and in the world.

Stigmas of holoparasitic Phelipanche arenaria (Orobanchaceae) – a suitable ephemeric flower habitat for development unique microbiome

“…Additionally, P. gessardii was recently reported to improve plants' response to Pb-toxicity soils [ 52 ]. Moreover, R. victoriana was recognised as plant pathogen associated with acute oak decline symptoms (also R. variigena ) [ 53 ], causing bacterial canker of Eucalyptus [ 54 ] but recent studies confirmed variety of beneficial features, including IAA production, phosphate solubilization, nitrogen fixation [ 55 ]. Pantoea agglomerans (this bacteria have been detected in immature and mature stigmas, by both methods) was described as plant pathogens and also occurs in plants as an epi- or endophytic symbiont [ 56 ].…”