WITHIN-PLANT RELATIONSHIPS AMONG WOUNDING, JASMONIC ACID, AND NICOTINE - IMPLICATIONS FOR DEFENSE IN NICOTIANA-SYLVESTRIS

Tn Nicotiana sylvestris Spegazzini and Comes (Solanaceae), we examined the relationships among wounding, endogenous leaf jasmonic acid (JA) pools, and whole-plant (WP) nicotine accumulation over a range of woun ding intensities and spatial distributions, in order to explore optima l defence (OD) theory predictions. We quantitatively wounded one or fo ur leaves and then quantified: (1) JA in damaged and undamaged leaves 90 min after wounding; (2) WP nicotine concentration after id (the tim es when JA and nicotine attain the largest wound-induced. concentratio ns). We find: (2) statistically significant, positive relationships on a leaf-by-leaf basis among the number of leaf punctures, endogenous l eaf JA, and WP nicotine accumulation; (2) that young, undamaged leaves have a higher concentration of JA than do older, undamaged leaves, an d produce a greater amount of JA per puncture than older leaves, but t hat all leaves have the same JA content (ng JA per leaf); and (3) that a damaged leaf produces less JA when other leaves in the canopy are w ounded than when it is the only wounded leaf in the canopy, but that w hen it is the only wounded leaf, the phylotactically adjacent, undamag ed leaves do not increase their JA concentrations. The observation tha t younger leaves produce more JA per puncture than do older leaves is consistent with OD theory predictions. The observation that a small am ount of damage localized to a single leaf is as effective as a larger amount of damage dispersed across the canopy in increasing leaf JA and WP nicotine accumulation shows the plant's ability to differentiate b etween dispersed and localized damage. Because the quantity of JA in a wounded leaf 90 min after wounding is a reliable indicator of the WP nicotine response to wounding, this trait provides insight into how pl ants integrate information about environmental insults and tailor thei r defence responses.