No interaction between methyl jasmonate and ozone in Pima cotton: growth and allocation respond independently to both |
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| Authors: | D A GRANTZ H‐B VU C AGUILAR M A REA |
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| Institution: | 1. Department of Botany and Plant Science and Air Pollution Research Center, University of California, Riverside, CA,;2. Kearney Agricultural Center, 9240 S. Riverbend Avenue, Parlier, CA 93648, USA and;3. Facultad de Quimica, Universidad Autonoma de Queretaro, Cerro de las Campanas, 76010 Queretaro, QRO, Mexico |
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| Abstract: | Ozone (O3) is damaging to plants, inducing signalling pathways involving antagonism between jasmonates and ethylene. These pathways mediate O3 responses, particularly to acute exposure, and their manipulation protected several species against acute and chronic O3. We use chronic daily exposure of up to 163 ppb O3, and twice weekly application of up to 320 µg plant?1 methyl jasmonate (MeJA) to test two hypothesizes: 1) a low rate of MeJA does not affect growth but increases O3 sensitivity; 2) a high rate inhibits growth but reduces O3 sensitivity. Both hypotheses were rejected. Growth declined with increases in both MeJA and O3. MeJA at 40 µg plant?1 caused no direct effect, and at 160 µg plant?1 reduced growth similarly at all O3. Neither rate altered O3 sensitivity. These additive responses are not consistent with protection by MeJA in this system. They may reflect inter‐specific differences in signalling, since O3 concentrations used here exceeded some reported acute exposures. Alternatively, parallel responses to O3 and MeJA may suggest that O3‐induced jasmonates play a developmental role in chronic response but no protective role in the absence of lesions characteristic of acute exposure. MeJA appears useful as a probe of these mechanisms. |
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| Keywords: | allocation biomass productivity methyl jasmonate O3 oxidants ozone |
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