Priming of plant defences against Pieris brassicae

• Applicant: Professor Mitja Remus-Emsermann, Ph.D., since 3/2023
• Subject Area: Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 502563004

Brassicaceae plants can take eggs laid by the Large White Butterfly Pieris brassicae onto their leaves as warning of imminent larval herbivory. Thus, egg-laden plants are primed for improved anti-herbivore defences against P. brassicae larvae. This project aims to gain deeper insights in the molecular mechanisms and ecological effects of priming of anti-herbivore defences in Brassicaceae plants. We focus on priming by insect eggs, but also on priming of anti-herbivore defences by prior larval feeding.Our previous studies showed that Arabidopsis thaliana’s response to P. brassicae eggs results in reduced larval performance. Feeding-damaged, regrowing plants benefit from their previous response to eggs by higher seed production. This egg-priming effect is based on enhanced feeding-induced levels of phytohormones (e.g. salicylic acid and jasmonic acid-isoleucine), flavonoids and of transcripts of primable genes like PATHOGENESIS-RELATED 5. Prior egg deposition seems to amplify and accelerate the feeding-induced plant defences. Furthermore, the priming effect was found to depend on the duration of time, for which eggs remain on a leaf, and on the developmental stage of the plant.The proposed project addresses the following three key questions pursuing three aims:1) (How) does the longevity of a brassicaceous plant (annual, multi-annual) impact on its egg-primability? This question is based on previous findings, which showed that the annual Brassicaceae species studied so far are primable by prior egg deposition. However, defence of the biannual A. lyrata against P. brassicae larvae is not primable by prior oviposition, whereas defence of the multi-annual species Brassica oleracea is. We AIM to elucidate the impact of the plant’s longevity on egg-mediated priming of anti-herbivore defences by comparing the primability of various annual and multi-annual brassicaceous plants growing at the same abiotic conditions.2) Because plant transcriptomic responses to insect eggs are similar to the response to larval feeding, we ask whether larval feeding primes defences against subsequently feeding larvae in a similar manner as egg deposition does. We AIM to find out whether such different insect-associated cues as larval feeding and egg deposition elicit similar “alarm” responses. We will study the ecological effects and molecular mechanisms of priming anti-herbivore defences by previous larval feeding in different Brassicaceae species with different longevity and compare the results with those obtained on egg-priming.3) Because the developmental time of P. brassicae eggs changes dependent on temperature increase or decrease, we ask how such temperature changes affect the kinetics of the plant’s egg-primed responses. Therefore, we will study the egg-primability of annual and multi-annual brassicaceous plants under changing, naturally occurring temperature conditions. These studies AIM to show how robust egg-priming under changing temperature conditions is.

• DFG Programme: Research Grants
• Ehemalige Antragstellerin: Dr. Vivien Lortzing, until 2/2023