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

TY - JOUR

T1 - 11C-imaging

T2 - methyl jasmonate moves in both phloem and xylem, promotes transport of jasmonate, and of photoassimilate even after proton transport is decoupled

AU - Thorpe, Michael R

AU - Ferrieri, Abigail P

AU - Herth, Matthias Manfred

AU - Ferrieri, Richard A

PY - 2007/7

Y1 - 2007/7

N2 - 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.

AB - 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.

KW - 2,4-Dinitrophenol

KW - 4-Chloromercuribenzenesulfonate

KW - Acetates

KW - Biological Transport

KW - Carbon Radioisotopes

KW - Carbonyl Cyanide m-Chlorophenyl Hydrazone

KW - Cyclopentanes

KW - Oxylipins

KW - Phloem

KW - Photosynthesis

KW - Tobacco

KW - Xylem

U2 - 10.1007/s00425-007-0503-5

DO - 10.1007/s00425-007-0503-5

M3 - Journal article

C2 - 17356850

SN - 0032-0935

VL - 226

SP - 541

EP - 551

JO - Planta

JF - Planta

IS - 2

ER -