12-Hydroxyjasmonic Acid Glucoside Is a COI1-JAZ-Independent Activator of Leaf-Closing Movement in Samanea saman    

Abstract

Jasmonates are ubiquitously occurring plant growth regulators with high structural diversity that mediate numerous developmental processes and stress responses. We have recently identified 12-O-b-D-glucopyranosyljasmonic acid as the bioactive metabolite, leaf-closing factor (LCF), which induced nyctinastic leaf closure of Samanea saman. We demonstrate that leaf closure of isolated Samanea pinnae is induced upon stereospecific recognition of (2)-LCF, but not by its enantiomer, (+)-ent-LCF, and that the nonglucosylated derivative, (2)-12-hydroxyjasmonic acid also displays weak activity. Similarly, rapid and cell type-specific shrinkage of extensor motor cell protoplasts was selectively initiated upon treatment with (2)-LCF, whereas flexor motor cell protoplasts did not respond. In these bioassays related to leaf movement, all other jasmonates tested were inactive, including jasmonic acid (JA) and the potent derivates JA-isoleucine and coronatine. By contrast, (2)-LCF and (2)-12-hydroxyjasmonic acid were completely inactive with respect to activation of typical JA responses, such as induction of JAresponsive genes LOX2 and OPCL1 in Arabidopsis (Arabidopsis thaliana) or accumulation of plant volatile organic compounds in S. saman and lima bean (Phaseolus lunatus), generally considered to be mediated by JA-isoleucine in a COI1-dependent fashion. Furthermore, application of selective inhibitors indicated that leaf movement in S. saman is mediated by rapid potassium fluxes initiated by opening of potassium-permeable channels. Collectively, our data point to the existence of at least two separate JA signaling pathways in S. saman and that 12-O-b-D-glucopyranosyljasmonic acid exerts its leaf-closing activity through a mechanism independent of the COI1-JAZ module.

Endoplasmic Reticulum-associated Inactivation of the Hormone Jasmonoyl-l-Isoleucine by Multiple Members of the Cytochrome P450 94 Family in Arabidopsis

“…The molecular organization of JA-metabolizing enzymes and metabolites in multiple subcellular compartments needs further investigation. Given the known biological activities of some oxidized-and glucosylated JAs (61,62), it is also possible that these JA-Ile derivatives may have molecular targets other than the COI1.…”

Cytochrome P450 CYP94B3 mediates catabolism and inactivation of the plant hormone jasmonoyl-L-isoleucine

“…The 12OH-JAs can be further metabolized to sulfoand glucosyl derivatives that are largely inactive in promoting responses typically attributed to jasmonate (13,16,17). However, the ability 12OH-JAs to induce certain physiological responses, including tuber formation and leaf closing, raises the possibility that these compounds signal independently of the COI1-JAZ receptor system (17,18).…”

“…Among the pathways implicated in catabolism of the hormone are conversion of JA and JA-Ile to their corresponding 12-hydroxy derivatives (12OH-JAs), 12OH-JA (also known as tuberonic acid) and 12OH-JA-Ile, respectively (11,(13)(14)(15). The 12OH-JAs can be further metabolized to sulfoand glucosyl derivatives that are largely inactive in promoting responses typically attributed to jasmonate (13,16,17). However, the ability 12OH-JAs to induce certain physiological responses, including tuber formation and leaf closing, raises the possibility that these compounds signal independently of the COI1-JAZ receptor system (17,18).…”

The Amidohydrolases IAR3 and ILL6 Contribute to Jasmonoyl-Isoleucine Hormone Turnover and Generate 12-Hydroxyjasmonic Acid Upon Wounding in Arabidopsis Leaves

“…TA formation has, however, been proposed as a partial switch-off in JA signaling (14). However, TA could also be a metabolic intermediate, for example, TA-glucoside was described as a specific signal triggering leaf closing in the rain tree Samanea saman (15).…”