Bacterial Canker Disease on Populus × euramericana Caused by Lonsdalea populi in Serbia

Abstract

Populus × euramericana (Dode) Guinier clone (cl.) “I-214” is a fast-growing interspecific hybrid between Eastern cottonwood (P. deltoides Bartr. ex Marsh) and European black poplar (Populus nigra L.). Populus × euramericana was introduced into Serbia in the 1950s and has become one of the most widely grown poplar species. In September 2019, cankers were observed on stems and branches of P. × euramericana cl. “I-214” trees in a two-year-old poplar plantation in the province of Vojvodina, Serbia. The canker tissue was soft and watery, and a colorless fluid that smelled rotten flowed from the cracks in the bark, suggesting possible bacterial disease. After two weeks, diseased trees experienced crown die-back and oozing of foamy, odorous exudates and this study aimed to identify the causal agent of the disease. Canker margins and exudates were collected from 20 symptomatic trees. The associated bacterium was isolated and identified using biochemical characteristics, phylogenetic analyses based on 16S rRNA gene sequences, and multilocus sequence analyses (MLSA) based on partial sequencing of three housekeeping genes (gyrB, infB, and atpD). The pathogen was identified as Lonsdalea populi. Pathogenicity tests were conducted on rooted cuttings of P. × euramericana cl. “I-214” in an environmental test chamber and demonstrated that the isolated bacterial strain was able to reproduce symptoms of softened, water-soaked cankers and exudation. To the best of our knowledge, this is the first report of L. populi causing bacterial canker disease on P. × euramericana cl. “I-214” in Serbia and in southeastern Europe (SEE). It is also the first report of a bacterial disease on hybrid poplars, including P. × euramericana in this country and in SEE. If the disease spreads into new areas, selection for L. populi resistance may need to be integrated into future poplar breeding programs.

The Threat of Pests and Pathogens and the Potential for Biological Control in Forest Ecosystems

“…Among them are cankers which are caused by a potentially fatal bacterium, Lonsdalea populi (formerly L. quercina subsp. populi) [61,62]. These diseases, characterized by a canker with white exudates, are confined to the bark of the trunk and branches, primarily in summer [62].…”

“…populi) [61,62]. These diseases, characterized by a canker with white exudates, are confined to the bark of the trunk and branches, primarily in summer [62]. A large percentage of the plantation area of P. × euramericana hybrid poplars in China and Hungary is affected by L. populi, which causes extensive damage to the plantations [63].…”

Trichoderma spp. from Pine Bark and Pine Bark Extracts: Potent Biocontrol Agents against Botryosphaeriaceae

“…Nucleotide sequences were examined for sequencing errors, edited, and assembled using BioEdit v. 7.2.5, and MEGA X, whereas sequence alignments were carried out using MEGA X and MAFFT v. 7 (on-line) as described in Zlatković et al [28]. Sequences of the three loci (ITS, tef 1-α, RPB2) were analysed individually and in combination following the GCPSR concept [29].…”

“…The phylogenetic analyses of the individual genes were carried out using Maximum Likelihood (ML) analyses, whereas analyses of the combined datasets (tef 1-α + RPB2), and (ITS + tef 1-α + RPB2) were performed using ML, Maximum parsimony (MP) and Bayesian analyses (BI). The ML and MP analyses were conducted using PhyML v. 3.0 (on-line) and PAUP v. 40b10 as described by Zlatković et al [8,28]. The BI analyses were carried out in MrBayes v. 3.0b4 as described in Kovač et al [27].…”

Botryosphaeria Dothidea and Neofusicoccum Yunnanense Causing Canker and Die-Back of Sequoiadendron Giganteum in Croatia

“…Sequences were examined, edited, assembled, and multiple sequence alignments were done using BioEdit v. 7.2.5, MEGA X and MAFFT v. 7 as described in Zlatković et al [25]. Sequence data of the three loci (ITS, tef 1-α, TUB2) were analysed individually and in combination, to assure that the evolutionary lineage is consistent in most of the analysed phylogenies [26].…”