Biology subjects

Abdala-Roberts, L.

Publications and source records attributed to Abdala-Roberts, L..

4 recordsLinked to original sources

bioRxiv2026

Exposure to herbivore-induced plant volatiles directly induces jasmonic acid and primes chemical defences in cotton plants

Plants can deploy alternative defensive strategies in response to airborne signals from damaged neighbours to prepare for incoming attack: a straightaway response up-regulating their defences (induction), or a primed state, leading to a faster/stronger defence response after herbivory. However, it is unclear which mechanisms are involved in each response. We used a monophagous and a polyphagous leafworm species to specifically dissect induction and priming effects of exposure to herbivore-induced plant volatiles (HIPVs). Exposure to HIPVs directly elevated jasmonate levels in undamaged receivers but did not induce defensive terpenoids or volatiles. However, HIPV-primed plants accumulated high levels of toxic terpenoids (e.g. gossypol) and emitted high quantities of volatile sesquiterpenes, when damaged by either species of caterpillars. This comprehensive study demonstrates that both defence induction and priming can be detected in cotton but occur as different, linked responses which are robust to herbivore identity, providing insights into a generalised plant communication strategy.

ecology↗

bioRxiv2025

From leaves to defenders: how amount and dispersion of leaf damage affect extrafloral nectar production and ant-mediated protection in wild cotton (Gossypium hirsutum)

O_LIExtrafloral nectar (EFN) drives mutualistic interactions between plants and ants. However, EFN production is costly, and its induction is predicted to vary with herbivore-related factors. We examine how the amount and within-plant damage spatial uniformity (i.e., dispersed and concentrated damage) affect EFN production and ant-mediated defence in wild cotton (Gossypium hirsutum). Previous work suggests that severe and concentrated damage is costliest to plants, leading us to hypothesise that such damage would induce greater EFN production and, consequently, stronger ant attraction and protection. C_LIO_LIWe conducted a greenhouse experiment in which plants were subjected to one of the following mechanical damage treatments: control (no damage), low damage (two damaged leaves, 30% of area removed each), high concentrated damage (two damaged leaves, 60% each), and high dispersed damage (four damaged leaves, 30% each; i.e., same total area than concentrated damage). The day after treatments, we measured EFN volume and sugar content from one nectary per plant (a per-nectary EFN response), and the number of secreting nectaries per plant (a proxy for whole-plant level EFN response). Subsequently, we performed a field experiment using the same treatments to evaluate EFN-mediated ant recruitment and ant-provided protection by placing caterpillars on plants. C_LIO_LIBoth high-damage treatments increased EFN volume per nectary, whereas low damage did not. However, against our prediction, dispersed damage was the only treatment that increased the number of secreting nectaries. Consistently, once placed in the field, plants with dispersed damage recruited more ants and caterpillars on them were more likely to be attacked by ants. C_LIO_LIContrary to expectations, plants subjected to dispersed damage exhibited a greater total investment in EFN, presumably via local induction of more nectaries per plant, and thereby enhancing ant-mediated defence. This study highlights the importance of herbivory intensity and within-plant spatial uniformity in shaping ant-plant interactions. C_LI

ecology↗

bioRxiv2025

Effects of variability in the amount and dispersion of within-plant herbivory on resistance- and tolerance-related responses in wild cotton

Herbivory triggers complex induced defensive responses in plants that may vary depending on the amount and dispersion of damage, the latter has received much less attention. We examined how wild cotton (Gossypium hirsutum) responds to different amounts of herbivory and how it is dispersed among the leaves (concentrated versus dispersed) using the specialist caterpillar Alabama argillacea. In a greenhouse experiment, plants underwent different herbivory treatments: no damage, low herbivory (two caterpillars, one on each of two leaves), high concentrated herbivory (four caterpillars, two on each of two leaves), and high dispersed herbivory (four caterpillars, each on one of four leaves). We measured extrafloral nectar (EFN), an indirect defense trait, and phenolic production, a direct chemical defense, as well as regrowth capacity (new leaf biomass two months after herbivory) as a tolerance proxy. To distinguish between local and systemic defense induction, we measured resistance-related responses on damaged and undamaged leaves. EFN was significantly and more consistently induced in damaged leaves (i.e., stronger local induction) in response to high dispersed damage. Phenolic compounds were not affected by any of the damage treatments. Additionally, wild cotton fully compensated for damage in terms of new leaf biomass under all herbivory treatments, except after high concentrated damage, suggesting higher costs incurred by this type of herbivory. These results highlight the importance of studying plant-induced defenses under varying herbivory conditions and suggest opposing effects on resistance-related (EFN, indirect) versus tolerance-related induced responses, which are known to affect tri-trophic interactions associated with wild cotton. Main ConclusionVariability in caterpillar damage to wild cotton leaves differentially shapes resistance- and tolerance-related responses; dispersed damage induces more extrafloral nectar production, and concentrated damage more strongly drives reductions in regrowth.

ecology↗

bioRxiv2024

Induction by caterpillars of stored and emitted volatiles among populations of wild cotton (Gossypium hirsutum)

BackgroundUpland cotton (Gossypium hirsutum) plants constitutively store volatile terpenes in their leaves, which are steadily emitted at low levels. Herbivory leads to a greater release of these stored volatiles. Additionally, damaged plants increase the accumulation of volatile terpenes in their leaves and begin to emit other terpenes and additional compounds. This has been well characterised for cultivated G. hirsutum, but little is known about volatile production in response to herbivory in wild populations. We investigated how damage by the beet armyworm (Spodoptera exigua) affects leaf-stored and emitted volatiles in wild G. hirsutum plants. These plants were grown in a greenhouse using seeds collected from populations found along the Yucatan coast, from where this cotton species originates. We assessed whether the differences in leaf terpene profiles between two known chemotypes persisted upon herbivory, in leaves and in head-space emissions, and whether these chemotypes also differed in the production and release of herbivory-induced volatiles. In addition to chemotypic variation, we further investigated intraspecific variation in the volatile response to herbivory among genotypes, populations, and four geographic regions. ResultsThe difference between the two chemotypes persisted after herbivory in the stored volatile profile of induced leaves, as well in the emissions from damaged plants. Therefore, wild cotton chemotypes may differ in their airborne interactions with their environment. The specific terpenes distinguishing these chemotypes showed a weak inducibility, raising questions about their functions. Herbivory triggered changes in stored and emitted volatiles similar to what is known for cultivated varieties of G. hirsutum. However, we report for the first time on the emission of volatile aldoximes by cotton plants, which were only detected in the headspace upon herbivory, and displayed chemotypic and interpopulation variation. Intraspecific variation was also observed in the induced emissions of nitriles and certain terpenes. Moreover, chemotypes differed in their induction of (E)-{beta}-ocimene stored in the leaves. ConclusionsThis comprehensive insight into herbivore-induced volatiles of wild cotton reveals variation in production and emission among populations. A full understanding of their ecological role may help in the development of future pest-management strategies for cotton crops.

plant biology↗