Distal Transport of Exogenously Applied Jasmonoyl-Isoleucine with Wounding Stress

Determining the mobile signal used by plants to defend against biotic and abiotic stresses has proved elusive, but jasmonic acid (JA) and its derivatives appear to be involved. Using deuterium-labeled analogs, we investigated the distal transport of JA and jasmonoyl-isoleucine (JA-Ile) in response to leaf wounding in tobacco (Nicotiana tabacum) and tomato (Solanum lycopersicum) plants. We recovered [H-2(2)-2]JA ([H-2(2)]JA) and [H-2(3)-12]JA-Ile ([H-2(3)]JA-Ile) in distal leaves of N. tabacum and S. lycopersicum after treating wounded leaves with [H-2(2)]JA or [H-2(3)]JA-Ile. We found that JA-Ile had a greater mobility than JA, despite its lower polarity, and that application of exogenous JA-Ile to wounded leaves of N. tabacum led to a higher accumulation of JA and JA-Ile in distal leaves compared with wounded control plants. We also found that exudates from the stem of S. lycopersicum plants with damaged leaflets contained JA and JA-Ile at higher levels than in an undamaged plant, and a significant difference in the levels of JA-Ile was observed 30 min after wounding. Based on these results, it was found that JA-Ile is a transportable compound, which suggests that JA-Ile is a signaling cue involved in the resistance to biotic and abiotic stresses in plants.