11C-imaging: methyl jasmonate moves in both phloem and xylem, promotes transport of jasmonate, and of photoassimilate even after proton transport is decoupled

Abstract

The long-distance transport and actions of the phytohormone methyl jasmonate (MeJA) were investigated by using the short-lived positron-emitting isotope 11C to label both MeJA and photoassimilate, and compare their transport properties in the same tobacco plants (Nicotiana tabacum L.). There was strong evidence that MeJA moves in both phloem and xylem pathways, because MeJA was exported from the labeled region of a mature leaf in the direction of phloem flow, but it also moved into other parts of the same leaf and other mature leaves against the direction of phloem flow. This suggests that MeJA enters the phloem and moves in sieve tube sap along with photoassimilate, but that vigorous exchange between phloem and xylem allows movement in xylem to regions which are sources of photoassimilate. This exchange may be enhanced by the volatility of MeJA, which moved readily between non-orthostichous vascular pathways, unlike reports for jasmonic acid (which is not volatile). The phloem loading of MeJA was found to be inhibited by parachloromercuribenzenesulfonic acid (PCMBS) (a thiol reagent known to inhibit membrane transporters), and by protonophores carbonyl cyanide 3-chlorophenylhydrazone (CCCP) and 2,4-dinitrophenol (DNP) suggesting proton co-transport. MeJA was found to promote both its own transport and that of recent photoassimilate within 60 min. Furthermore, we found that MeJA can counter the inhibitory effect of the uncoupling agent, CCCP, on sugar transport, suggesting that MeJA affects the plasma membrane proton gradient. We also found that MeJA's action may extend to the sucrose transporter, since MeJA countered the inhibitory effects of the sulfhydryl reagent, PCMBS, on the transport of photoassimilate.

Collection and Analysis of <em>Arabidopsis</em> Phloem Exudates Using the EDTA-facilitated Method

“…Alternatively, they could serve as a source of cytokinin or signal the metabolic status of the plant . Jasmonic acid, an oxylipin moves through the phloem as part of the response to pathogen infection 22,29,31,32 . While the role of most phloem lipids is still unclear, some of them likely have signaling function 4 .…”

Jasmonic acid control of GLABRA3 links inducible defense and trichome patterning inArabidopsis

“…Wounded tissue rapidly activates JA biosynthesis (Glauser et al, 2008), and increased JA triggers the SKP1/Cullin/F-box E3 ubiquitin ligase complex containing the F-box subunit CORONATINE INSENSITIVE1 (SCF COI1 ) to degrade the repressors of JA signaling -the JASMONATE-ZIM (JAZ) family proteins -by the ubiquitin/26S-proteasome pathway (Chini et al, 2007;Thines et al, 2007). In addition to their local synthesis and action, JAs also move systemically via vascular strands to transmit wound signals to distal tissues (Li et al, 2002;Thorpe et al, 2007). Therefore, JAs can be considered to be good candidates for the mediator of wound-induced trichome formation, which is also a systemic response.…”

The effect of cis-jasmone, jasmonic acid and methyl jasmonate on accumulation of anthocyanins and proanthocyanidins in seedlings of common buckwheat (Fagopyrum esculentum Moench)

“…There was strong evidence that MJ moves in both phloem and xylem. Methyl jasmonate moves in tobacco phloem along with photoassimilates, and due to exchange between phloem and xylem is able to move in xylem as well (Thorpe et al 2007). In contrast, it was reported that jasmonic acid does not exchange between phloem and xylem, probably due to its chemical properties (Zhang and Baldwin 1997).…”