Controlling peach fruit quality by interfering with ethylene production with polyamines and jasmonates

In climacteric fruit, the control of ripening mainly relies on ethylene production and/or action, although there are some parameters that do not seem to strictly respond to this hormone. The peach fruit is well characterized from the physiological and molecular point of view and thus it offers a good fruit model system to study the relationship between ripening and quality. Here we review the results of the application of two kinds of natural growth regulators, polyamines (PAs) and jasmonates (JAs). Although characterized by substantially different biological activities, both are able to interfere with ethylene synthesis and perception, and, as a consequence, to alter the progression of ripening and the evolution of the main fruit quality traits. On the basis of endogenous levels of PAs and JAs in the fruit, experimental protocols aimed at manipulating these levels were established. This article reports the main results obtained in relation to fruit ripening and quality, and functional properties. Field application to peach fruit in late developmental stage (S3-S4) of the PAs putrescine (Pu), spermidine (Sd) or spermine (Sm) leads almost invariably to ripening delay and prolonged shelf-life. This is due to inhibition of ethylene biosynthesis/production, inhibition of cell wall-dismantling activity/retention of flesh firmness (FF), reduced soluble solids concentration (SSC). Equally, in the case of JAs, their application in planta causes a ripening delay, as shown by reduced ethylene biosynthesis/production and firmness retention probably due to a trade-off between growth and defence. Although likely via different signal transduction pathways, PAs and JAs, by interfering with ethylene biosynthesis and perception, lead to a less ripe fruit and, consequently, they are very promising compounds for quality control in the postharvest handling chain. For practical purposes, besides optimizing application strategies, commercial products containing PAs would be highly desirable.