Variation in herbivory-induced responses within successively flushing Quercus serrata seedlings under different nutrient conditions

Abstract

Herbivore damage can induce the host plant to alter the chemical and physical qualities of its leaves, which is thought to be a plant strategy-termed ''induced response''-for avoiding further herbivory. In woody plants, many studies have considered variation in induced response with resource availability, but few studies have examined this variation in relation to growth patterns of woody plants. We studied the phenotypic variability of induced response within successively flushing Quercus serrata seedlings. Q. serrata seedlings were grown under controlled conditions. The controlled factors were herbivore damage (herbivore-damaged and -undamaged) and soil fertility (low and high). At each flush stage, the concentrations of condensed tannin (CT), total phenolics (TP), and nitrogen (N) in leaves were analyzed, and the leaf mass per area (LMA) was measured. CT and TP concentrations in leaves and LMA were higher in herbivore-damaged seedlings. Leaves of the first flushes showed greater sensitivity to herbivore damage and had a higher CT concentration than leaves of the later flushes. Furthermore, seedlings growing in low-fertility soil showed a greater induced response. The results suggest that the induced response of Q. serrata seedlings was related to the contributions of the tissue to current productivity. Leaves of the first flush showed a greater induced response, possibly because they play an important role in subsequent growth. The potential of Q. serrata seedlings to adjust the properties of leaves depending on herbivory and soil fertility in relation to growth patterns may be advantageous on the forest floor, where seedlings grow in soil of heterogeneous fertility and are constantly exposed to herbivory.

Tougher and thornier: general patterns in the induction of physical defence traits

“…Additional studies in the field measuring induction by naturally occurring herbivory undoubtedly include responses to multiple species (Rohner & Ward ; Milewski & Madden ; Mizumachi et al . ; Frederickson et al . ), but without controlling herbivore identities, it is impossible to assess specificity.…”

“…For example, induction of trichomes in B. nigra varied significantly in magnitude and timing in response to three different insect species (Traw & Dawson 2002). Additional studies in the field measuring induction by naturally occurring herbivory undoubtedly include responses to multiple species (Rohner & Ward 1997;Milewski & Madden 2006;Mizumachi et al 2012;Frederickson et al 2013), but without controlling herbivore identities, it is impossible to assess specificity.…”

Antioxidant Capacity Of Wyoming Big Sagebrush (Artemisia tridentataSSP.Wyomingensis) Varies Spatially and is Not Related to the Presence of a Sagebrush Dietary Specialist

“…As such, we predicted that plants browsed by pygmy rabbits would have fewer polyphenols and therefore fewer antioxidants. Alternatively, high-browsed plants could have more antioxidants than low-browsed plants based on studies showing that browsing by herbivores in creases total polyphenol content of plants (Bi and Felton 1995, Nykanen and Koricheva 2004, Wang et al 2011, Mizumachi et al 2012). We did not find any significant differences in antioxidant capacity or in total amount of polyphenolics between high- and low-browsed plants within geographical sites within a season.…”

“…One mechanism by which plants can minimize oxidative stress is through the synthesis of polyphenols, a group of plant secondary metabolites (PSMs) that possess antioxidant capacity (Pandey and Rizvi 2009). Specifically, stress from ultraviolet (UV) light, temperature extremes, pathogen infection, and browsing by herbivores is often correlated with higher concentrations of polyphenols with antioxidant capacity (Bahnweg et al 2000, Kondo and Kawashima 2000, Yarnes et al 2008, Mizumachi et al 2012). For example, chlorogenic acid has antioxidant properties and accumulates in plant tissue in response to high light (Izquierdo et al 2011) and elevated UV-B (Kondo and Kawashima 2000).…”

“…Catechin, another polyphenol with antioxidant properties, increases in plants in response to inoculation with pathogenic fungi (Bahnweg et al 2000). Browsing by herbivores can also increase total polyphenol content in plants by causing leaf damage (Nykanen and Koricheva 2004, Wang et al 2011, Mizumachi et al 2012). …”