Relationship between growth and respiration induced by lipids in pea stem sections.

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Abstract
Emulsions of triolein, methyl oleate, and palmitonitrile at concentrations of 50 micromolar and less significantly increased within 2-3 hours both the elongation and respiration of stem sections excised from red light-grown seedlings of Pisum sativum. The lipid enhancement of elongation required the presence of an auxin hormone and produced greater growth than any combination of hormones alone, but the lipid-induced respiratory increase was found in the absence of auxin as well as under other conditions where elongation does not occur. Experiments with C14 labelled lipids proved that the lipid induced increase in respiration was far more than could be attributed to the use of the lipid as a respiratory substrate. It is concluded that the effect of lipids on plant growth is related, but secondary to, their effect on tissue respiration. Pea stem section growth was also sensitive to CO2- Dodecenyl succinate, which modifies the movement of water through some plant membranes, was only inhibitory to growth and respiration at 10-5 to 10-3 [image] in this bioassay. The possible relationship of various detergent and lipid effects on other plant materials is discussed.