Biomedical subjects

Pierluigi Bonello

Publications and source records attributed to Pierluigi Bonello.

4 recordsLinked to original sources

PubMed2004

Systemic induction of traumatic resin ducts and resin flow in Austrian pine by wounding and inoculation with Sphaeropsis sapinea and Diplodia scrobiculata.

The potential role of the resin system in the response of Austrian pine (Pinus nigra Arn.) seedlings to mechanical injury and fungal infection was studied in greenhouse experiments. Anatomical observations were performed on 2-year-old plants wounded at collar level and inoculated with Sphaeropsis sapinea (Fr.: Fr.) Dyko & Sutton in Sutton or Diplodia scrobiculata (J. de Wet, B. Slippers & M. J. Wingfield, sp. nov.; sensu de Wet et al. 2003), two fungal pathogens that cause shoot blight and canker on conifers, and that are characterized by different levels of aggressiveness. Histological examination of host tissue taken from the stem at 0, 8, and 12 cm above the treatment site revealed significant treatment- and time-dependent effects on the course of locally and systemically induced traumatic resin duct (TRD) development. Occurrence of TRDs was observed after 4 days only in seedlings inoculated with D. scrobiculata. At 12 days, TRDs were present also in mock-inoculated controls. No TRDs appeared in seedlings inoculated with S. sapinea. However, S. sapinea caused loss of vacuolar phenolics, severe disruption of cambial tissue and invaded the host xylem quickly and apparently unimpeded, whereas D. scrobiculata was never detected in the host xylem. Five-year-old Austrian pines subjected to the same stem base treatments were used to determine the resin mass flowing from the stem 30 cm above the treatment sites. Wounding and/or inoculation induced a significant, 8.3-fold average increase in systemic resin flow over the untreated trees 3 weeks after basal treatment, suggesting that wounding is the sole prerequisite for systemic induction of resin flow. The results are discussed in the context of current disease resistance models.

Ascomycota↗

PubMed2003

Systemic effects of Heterobasidion annosum on ferulic acid glucoside and lignin of presymptomatic ponderosa pine phloem, and potential effects on bark-beetle-associated fungi.

Concentrations of soluble phenolics and lignin in the phloem of ponderosa pines inoculated with the pathogen Heterobasidion annosum were assessed over a period of 2 years in a 35-year-old plantation in northern California, USA. The major effect of the pathogen on phloem-soluble phenolics consisted of a significant accumulation of ferulic acid glucoside: 503 +/- 27 microg/g fresh weight (FW), compared with 366 +/- 26 microg/g FW for mock-treated and 386 +/- 27 microg/g FW for control trees. Lignin content was negatively correlated with ferulic acid glucoside concentration, and there was an indication of lignin reduction in the cell walls of inoculated trees. Lignin had a negative effect on the in vitro growth of two common bark beetle fungal associates. Ceratocystiopsis brevicomi and Ophiostoma minus. For this reason it, is hypothesized that lower lignification may facilitate the growth of beetle-associated fungi, resulting in greater susceptibility of the presymptomatic host to bark beetle colonization.

Adaptation, Physiological↗

PubMed2003

Feeding response of Ips paraconfusus to phloem and phloem metabolites of Heterobasidion annosum-inoculated ponderosa pine, Pinus ponderosa.

In studies of feeding by the bark beetle, Ips paraconfusus, two pine stilbenes (pinosylvin and pinosylvin methyl ether), ferulic acid glucoside, and enantiomers of the four most common sugars present in ponderosa pine phloem (sucrose, glucose, fructose, and raffinose) did not stimulate or reduce male feeding when assayed on wet alpha-cellulose with or without stimulatory phloem extractives present. When allowed to feed on wet alpha-cellulose containing sequential extracts (hexane, methanol, and water) of ponderosa pine phloem, methanol and water extractives stimulated feeding, but hexane extractives did not. Males confined in wet alpha-cellulose containing aqueous or organic extracts of culture broths derived from phloem tissue and containing the root pathogen. Heterobasidion annosum, ingested less substrate than beetles confined to control preparations. In an assay using logs from uninoculated ponderosa pines, the mean lengths of phloem in the digestive tracts increased as time spent feeding increased. Males confined to the phloem of basal logs cut from ponderosa pines artificially inoculated with H. annosum ingested significantly less phloem than beetles in logs cut from trees that were (combined) mock-inoculated or uninoculated and did not contain the pathogen. However, individual pathogen-containing treatments were not significantly different from uninoculated controls. It was concluded that altered feeding rates are not a major factor which may explain why diseased ponderosa pines are colonized by I. paraconfusus.

Animals↗

PubMed2003

Metabolite profiling as a functional genomics tool.

Plants accumulate a very large number of small molecules (phytochemicals) with important functions in the ecology of plants and in the protection against biotic and abiotic stress conditions. Little is known on how phytochemical biosynthetic pathways are regulated, which is a key step to successfully engineering plant metabolism. Plant natural products are usually not essential, and genetic analyses often fail to identify phenotypes associated with the absence of these compounds. We have investigated the use of metabolite profiling of plant cells in culture to establish the function of transcription factors suspected to control plant metabolic pathways.

Cell Culture Techniques↗