Chemical and physical plant defence across multiple ontogenetic stages in a tropical rain forest understorey tree

Abstract

Summary 1.Variation over plant ontogeny can play an important role in shaping trade-offs between investing resources in growth, reproduction and defence. Most previous ontogenetic studies on plant defence have compared two life stages, making it impossible to follow complete ontogenetic trajectories for plant defence traits. 2. We used the highly defended rain forest understorey tree Ryparosa kurrangii to examine chemical (cyanogen concentrations; CN M ) and physical (leaf mass per area; LMA) ontogenetic defence trajectories across multiple stages of development for the first time, using field and glasshouse plants. 3. In glasshouse seedlings, total plant cyanide and CN M decreased between cotyledon-bearing and recently autonomous seedlings. In field populations, foliar CN M decreased in a nonlinear fashion and showed a trade-off with LMA through the ontogenetic progression from small seedlings to large mature trees. 4. Cyanogenesis was ubiquitous in all individuals tested, with considerable quantitative plasticity in constitutive expression. Environmental influences on defence traits, as measured by foliar nitrogen and potential light availability in the field, had no detectable effect on CN M . Non-cyanide nitrogen (N -N CN ) M was negatively correlated with CN M , and N CN was negatively correlated with plant height; therefore, at constant plant height there was no relationship between (N -N CN ) M and CN M . LMA was positively correlated with increasing light availability. 5. Our results suggest that light and nitrogen availability have no detectable effect on CN M in R . kurrangii and that most of the observed population-level CN M plasticity may be due to underlying genetic and ontogenetic influences. These findings are related to a theoretical model recently proposed for resistance trajectories during plant ontogeny, taking into account the life-history traits of rain forest understorey trees. 6. Synthesis . The nonlinear ontogenetic trajectory of plant defence expression observed in this study suggests that ontogenetic defence changes may be strongly influenced by plant life-history traits, the defence(s) examined and the environmental niche the plant occupies.

Ontogenetic changes in anti‐herbivore defensive traits in leaves of four Mediterranean co‐occurring Quercus species

“…Accordingly, as other researchers have pointed out (Goodger et al 2006;Ochoa-Lo´pez et al 2015), defensive strategies can vary in different growth stages depending on the pressures that operate in each case. The greater resource limitations for defensive mechanisms in seedlings with respect to mature trees would explain that at intraspecific level we do observe a compromise between chemical and physical defences, which has also been found by other authors (Eck et al 2001;Cornelissen et al 2009;Webber and Woodrow 2009). Since investment in anti-herbivore defences is assumed to reduce the resources available for growth (Koricheva 2002;Strauss et al 2002), one could expect that resource constraints on seedlings would not allow several defensive mechanisms to simultaneously occur.…”

“…For example, during plant maturation, the amounts of chemical defences in leaves have been found to decrease in some studies (Donaldson et al 2006;Ochoa-Lo´pez et al 2015) and to increase in others (Herms and Mattson 1992;Boege and Marquis 2005). Similarly, both decreases (Gowda and Palo 2003;Boege 2005) and increases in physical defences (Webber and Woodrow 2009;Barton and Koricheva 2010) have been reported along ontogeny. In some cases, plant age had no significant effect on the physical (Wang et al 2016) or chemical (Loney et al 2006) defensive traits.…”

Quantitative and qualitative shifts in defensive metabolites define chemical defense investment during leaf development inInga, a genus of tropical trees

“…; Loney et al. ; Webber and Woodrow ; Koricheva and Barton ). However, a meta‐analysis (Koricheva and Barton ) found that some chemical classes show no change (cyanogenic glycosides and condensed tannins) or were higher in mature than in young leaves (sesquiterpenes).…”

“…Such changes in defenses could be related to the fact that expanding leaves are highly vulnerable to herbivores (Coley and Barone 1996). Other studies on woody plants also generally support higher concentrations of secondary metabolites for young leaves (Coley 1983;Mihaliak and Lincoln 1989;Gleadow and Woodrow 2000;Brenes-Arguedas et al 2006;Loney et al 2006;Webber and Woodrow 2008;Koricheva and Barton 2012). However, a meta-analysis (Koricheva and Barton 2012) found that some chemical classes show no change (cyanogenic glycosides and condensed tannins) or were higher in mature than in young leaves (sesquiterpenes).…”

No signs of meristem senescence in old Scots pine

“…The link with Induction of Chemical Defenses suggests a role for an ontogenetic control of the level of chemical defenses in trees (e.g. Boege & Marquis 2005;Webber & Woodrow 2009). The relationship between age and Initiation of Reproductive Structures suggests the existence of agerelated patterns in gibberellins, which have been shown to be involved in regulating the transition of meristematic buds from the vegetative to the reproductive state in several conifers (Haffner et al 1991;Vald es et al 2002;Vald es, Fern andez & Centeno 2003.…”