ISHS Acta Horticulturae 631: XXVI International Horticultural Congress: Issues and Advances in Transplant Production and Stand Establishment Research
NEW SUPPORT FOR THE INVOLVEMENT OF ETHYLENE IN LETTUCE GERMINATION AT SUPRA-OPTIMAL TEMPERATURE |
| Authors: | I. Kozareva, D.J. Cantliffe, R.T. Nagata, H.J. Klee |
| Keywords: | Lactuca sativa L., thermoinhibition, thermodormancy, seeds, ethylene, stress |
| Abstract:
This study provides new evidence for a role for ethylene in lettuce germination. The inhibitor, silver thiosulfate (STS) is able to bind and block ethylene receptors and, in that way, prevents subsequent ethylene-induced physiological responses. STS-mediated inhibition of lettuce germination was strongly dependent on both cultivar and temperature. Germination of the thermotolerant cultivar ‘Everglades’ (EVE) in 20 mM STS decreased from 97% at 20ºC to 20% at 36ºC. Thermosensitive ‘Dark Green Boston’ (DGB) seeds did not germinate in 20 mM STS at any temperature. When 10 mM STS was applied to DGB and EVE seeds, germination of EVE seeds at 35ºC and DGB at 20ºC and 35ºC was significantly reduced. Application of 1-aminocyclopropane-1-carboxylic acid (ACC) increased DGB germination at 35ºC to 92% as compared to 5% in water and 2% in 20 mM STS. Since the effect of STS could be negated by simultaneous application of ACC in DGB at optimal temperature and in EVE at both optimal and supra-optimal temperatures, possibly the differences observed between the effects of STS on germination of the two cultivars were due to differences in ethylene production and/or sensitivity. Using the triple response bioassay, the sensitivity of seeds of the two cultivars to ethylene and STS was examined. No differences between DGB and EVE were observed. This indicated that there might be a difference in ethylene production between the two cultivars that led to the difference in their ability to germinate at supra-optimal temperature and in the presence of STS. | |
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