| Abstract Detail
Tuesday Afternoon Ecology and Adaptation Walling, Linda [1], Fowler, Jonathan [1], Aromdee, Dale [1], Pautot, Veronique [2], Holzer, Frances [1]. Leucine aminopeptidase: A regulator of insect defenses in the Solanaceae. WHEN damaged, plants activate the octadecanoid pathway, which results in the production of a variety of oxygenated lipids, including the potent signaling molecule jasmonic acid (JA). JA activates a cascade of wound responses that are temporally (early and late) and spatially (local and systemic) regulated. In tomato, late wound-response genes include the serine proteinase inhibitors (Pins), polyphenol oxidases (PPOs), and leucine aminopeptidase (LapA). Pins and PPOs have well-established roles in deterring insect herbivory and reducing insect growth. LapA genes are found in a small subset of the Solanaceae. Using LapA-silenced (LapA-SI) and LapA-overexpressing (LapA-OX) lines, we demonstrate that LAP-A is the first plant aminopeptidase with a role in signal transduction and defense. LAP-A is a key regulator controlling late wound-responses, while early wound-responses are LAP-A independent. In LapA-SI lines, wound-response genes (pin1, pin2 and PPO-F) are expressed at lower levels and for shorter times than wild-type (WT) plants. Accordingly, LapA-SI lines are hypersusceptible to Manduca sexta feeding. M. sexta larval masses are 2-fold greater on LapA-SI lines than WT. Defenses are not restored by JA suggesting that LAP-A acts downstream of JA biosynthesis. LapA-OX tomato lines express high levels of LapA RNAs and proteins in both healthy and wounded tissue. Although LAP-A is active constitutively, LapA-OX plants do not accumulate pin RNAs until wounded indicating LAP-A is necessary but not sufficient for wound signaling in tomato. After wounding, LapA-OX lines accumulate Pin1, Pin2 and PPO RNAs at higher levels and persist for longer times than WT plants. Hyperactivation is observed both locally and systemically. LapA-OX plants are more resistant to insects, incurring less tissue damage and inhibiting both M. sexta growth and development. The temporal and spatial changes in WT and LapA-SI lines are being investigated using potato microarrays to reveal potential mechanisms of LAP-A action in the Solanaceae.
Log in to add this item to your schedule
Related Links:
Center for Plant Cell Biology
1 - University of California at Riverside, Botany and Plant Sciences, Center for Plant Cell Biology, Riverside, CA, 92521, USA
2 - Institute National de la Recherche Agronomique, Laboratoire de Biologie Cellulaire, Route de St. Cyr, 78026 Versailles Cédex, , France
Keywords:
herbivory
insect feeding
wounding
leucine aminopeptidase
LapA
defense
tomato
Jasmonic acid
proteinase inhibitor
polyphenol oxidase.
Session: SOL05-2
Location: Ballroom AB/Monona Terrace
Date: Tuesday, July 25th, 2006
Time: 2:00 PM
Abstract ID:317 |
