Observation and identification of wood decay fungi from the heartwood of peach tree limbs in central Georgia, USA

Abstract

Peach tree health, longevity, and limb strength can be affected by wood decay fungi, but the extent of the colonization and their identities have not been characterized in Georgia, United States of America. In an incubation experiment, dense white fungal mycelium grew on the cross-cut faces of asymptomatic limb sections sampled from peach scion cultivars, but no mycelium grew on those from rootstock cultivars. Among the scion cultivars, a Chi-square analysis indicated significant differences in the incidence of colonization. A dissection of six broken peach tree scaffold limbs showed symptoms of colonization along the entire length of the limbs. Only 41 % of primary branches had symptoms of wood decay, but no secondary branches appeared to have symptoms. Next generation sequencing (NGS) and metagenomic analysis of a combined DNA sample revealed the contigs were aligned to sequences of Trametes versicolor and/or Schizophyllum commune, suggesting these two white-rot fungi were present in the sample tested. Sanger sequencing confirmed two fragments of the same size but distinct nucleotide peak intensities were amplified from the sample used for NGS by two pairs of primers, providing supporting evidence that the two fungi were in the bulk sample but might differ in abundance or incidence. Subsequent multiplexing polymerase chain reaction diagnostics of ten scion samples confirmed the dominance of Trametes spp. (all ten samples), although Stereum spp. (five samples), Schizophyllum spp. (three samples) and Hericium spp, (one sample) were sometimes found coexisting with Trametes spp. Future research needs on this peach-fungus association are discussed.

Insights Into the Etiology of Gummosis Syndrome of Deciduous Fruit Trees in Israel and its Impact on Tree Productivity

“…Growers in Israel (S. Antman, chief officer at the Israeli extension service; personal communication) and in other places (Beckman, Pusey et al 2003), regard their orchards as undamaged and believe that the attainable yields are reached. Wood decay fungi, in our case Phellinus sp., were also isolated from necrotic tissues (Table 1; (Adaskaveg, Miller et al 1993;Chen, Bock et al 2015). Wood decay fungi, in our case Phellinus sp., were also isolated from necrotic tissues (Table 1; (Adaskaveg, Miller et al 1993;Chen, Bock et al 2015).…”

“…Nattrass (Nattrass 1933) reported that Hendersonula sp. The presence of wood decay fungi in association with the syndrome has been also described on peach (Adaskaveg, Miller et al 1993) and nectarine in the USA and Canada (Chen, Bock et al 2015). was the causal agent of the gummosis syndrome on apples, plum and apricot in Egypt.…”

“…(synonym to Neoscytalidium sp.) These fungi not only use the tree's resources, but the decay process weakens limbs and reduces their ability to bear load (Chen, Bock et al 2015). During the 1960's the disease was described in the United States and Japan and Botryosphaeria dothidea was isolated from symptomatic trees (Weaver 1974;Ogawa, Zehr et al 1995).…”

Population Structure and Phylogeny of Some U.S. Peach Cultivars

“…As a result, the natural and conventional selection might have resulted in loss of many agriculturally important genes with traits that were not easily visible or constitutively expressed, and in reduction of genetic diversity among peach cultivars. For example, compared with that of native wild peach trees, lifespan of commercial peach trees is substantially reduced, primarily due to heartwood decay in the scaffolds (Chen et al, 2015). The decay does not occur in several rootstock and wild Prunus accessions, suggesting the reduction probably is due to loss of defense-related genes because organoleptic fruit characteristics and yield often are among top factors evaluated during selection of scion cultivars.…”

A Metagenomic Survey of Wood Decay Fungi in the Urban Trees of Singapore

“…Full metagenomic data for 245 samples were obtained, each with 50,000-100,000 clean sequence reads, which were further assigned to various genotypes in the form of final ASVs (amplicon sequence variables). Using 90.0, 95.0, 96.0, 97.0, 98.0 and 99.0% sequence similarity thresholds, clustering revealed 13,953,18,146,19,399,21,154,22,067 and 23,356 main OTUs (operational taxonomic units), respectively. Furthermore, 98% was used as the cut-off threshold for the final clustering to be consistent with a previous study [7] on global soil funga diversity.…”