Anatomical and Chemical Responses of Eastern White Pine (Pinus strobus L.) to Blue-Stain (Ophiostoma minus) Inoculation

Abstract

The increases in temperature have recently allowed the southern pine beetle (Dendroctonus frontalis Zimm.; SPB) and its associated fungi to expand its natural range to northern pine forests. In this study, vigorous eastern white pine mature trees were used to evaluate constitutive and induced response to the southern pine beetle, using O. minus as a proxy. We evaluated histological and chemical changes in P. strobus in response to the fungus at 28and 65-days post inoculation (dpi). Inoculation with O. minus resulted in an induced defense response as evidenced by the increased production of traumatic resin duct, and lesion development surrounding the site of infection. Starch granules accumulated in the epithelial cells surrounding the resin ducts of inoculated trees. Chemical analyses showed that among phloem phenolics, epi/catechin and three unknown compounds were significantly upregulated at 28 dpi due to fungal inoculation. Several phloem terpenoids (α-pinene, β-myrcene, limonene, terpinolene and β-pinene) were significantly increased in inoculated trees compared to controls at both, 28-and 65-dpi. Continuous production of these terpenoids (up to 65 dpi) can be energetically costly for P. strobus as carbohydrate reserves fund monoterpene synthesis, reducing carbon availability necessary for tree development. Induced phenolics along with monoterpenes production and traumatic resin ducts observed in these trees, suggests that vigorous white pine may sustain endemic populations of southern pine beetle and vectored fungi.

Pyrogenic Carbon Increases Pitch Pine Seedling Growth, Soil Moisture Retention, and Photosynthetic Intrinsic Water Use Efficiency in the Field

“…Whether or not fire proves to be a long-term solution to southern pine beetle persistence (Lesk et al, 2017), it would be very useful to identify whether forest or prescribed fire play a decisive role in slowing acceleration of blue stain fungi aggregation (Ophiostoma minus) associated with southern pine beetle (Arango-Velez et al, 2018). Following such a study, if results warranted, an analysis of anthropogenic PyC inputs might also be advantageous.…”

Tree defence and bark beetles in a drying world: carbon partitioning, functioning and modelling

“…However, the activation, synthesis and accumulation of combined constitutive and induced SMs may be too slow to reach effective levels against mass‐attacking beetles and prevent lethal damage, when populations are high (Boone et al ., ). In addition, field studies have shown that local NSC storage was used for production of induced SMs in response to simulated or actual bark beetle attack (Raffa et al ., ; Roth et al ., ) or fungal infection (Goodsman et al ., ; Arango‐Velez et al ., ), while NSC stored in distant organs could not be mobilized to attacked stem sections (Wiley et al ., ). Such results indicate that mobilization and transport of NSC play an important role in allocation to induced defence in conifers.…”

Localization of (+)-Catechin in Picea abies Phloem: Responses to Wounding and Fungal Inoculation

“…In several plant species, catechins have been found to provide protection against, for example, oxidative stress, herbivore attacks, and bacterial invasions. In conifers, catechin production is induced in response to inoculation with E. polonica [27][28][29], ophiostomatoid fungi [28,30], and other fungal pathogens [31]. Within the last decade, new light has been shed on catechin biosynthesis and functions as defensive compounds in Norway spruce [31][32][33][34].…”