Time sequence of the effect of ethylene on transport, uptake and decarboxylation of auxin

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The effect of ethylene on the uptake, decarboxylation and basipetal transport of IAA-1-^<14>C, IAA-2-^<14>C and NAA-1-^<14>C in cotton stem sections (Gossypium hirsutum L., var. Stoneville 213) was studied. A reduction in the capacity of cotton stern sections to transport auxin basipetally appears in sections excised from plants exposed to ethylene for only 3 hr and increases with fumigation time. In addition to reducing transport, increasing ethylene pretreatment periods from 3 to 15 hr also progressively reduced the uptake of ^<14>C and increased the release of ^<14>C as ^<14>CO_2 from IAA-1-^<14>C. The effect of ethylene on the decarboxylation of IAA-1-^<14>C: was significant when expressed as either the cpm of ^<14>C released per hr per mg dry weight or the cpm released per hr per mm^2 in contact with the IAA donor. Comparative experiments using IAA-1-^<14>C and IAA-2-^<14>C demonstrated that the effect of ethylene on the decarboxylation of IAA was primarily a cut surface effect which apparently contributes to the reduction of IAA uptake by ethylene. Although ethylene significantly reduced the transport of NAA-1-^<14>C, uptake was significantly increased rather than decreased as with IAA-1-^<14>C while decarboxylation was unaffected. Ethylene pretreatment caused no significant changes in the dry weight or the cross-sectional area of the absorbing surface of the transport tissue.
日本植物生理学会の論文