New support for the involvement of ethylene in lettuce germination at supraoptimal temperature
l. Kozareva, D.J. Cantliffe, R.T. Nagata, and H.J. Klee
ISHS Acta Horticulturae 631: 31-37.
2004
บทคัดย่อ
Sliver Thiosulfate (STS), an ethylene inhibitor, was reported to reduce germination of seeds of the thermotolerant genotype’Everglades form 100% to 49% at 35 0C (Nascimento, 1998). It was suggested that ethylene was necessary for lettuce germination at supraoptimal temperature and that the effect of STS was due to its inhibition of ethylene action. The STS-induced reduction in germination was found to be both temperature and concentration dependent. With the increase in temperature at imbibition from 20 0C to 24 0C, 28 0C, 32 0C and 36 0C, the percentag of germinated seds remained almost constant in water (100% at 20 0C compared to 92% at 36 0C). ln STS, germination decreased from 100% at 20 0C to 99%, 79%, 39% and 22% at the respective higher temperatures. With increasing molarity of the STS solution from 1 to 5, 20 and 50 mM the percentage of germinated seeds at 35 0C was reduced from 97% to 91%, 46% and 0%. This decreaes was not observed at 20 0C, except at the highest molarity at which germination was 67%. The effect of STS can be negated by simultaneous application of 1-aminocyclopropane-1-carboxylic acid (ACC). After transfer from STS to water the seeds germinated 100%. Seedlings which developed from seeds transfer from STS to water had a phenotype typical for plants treated with an ethylene inhibitor-long radicles, no root hair, and altered gravitropic response. Sensitivity of ‘Everglades’ seeds to ethylene and STS was examined using a triple response assay. With the increase in ACC from 0 to 3 μM, the length of seedling exposed only to ACC decreased from 8.7 cm to 4 cm compared to a decrease in ACC and STS exposed seedlings from 8.8 to 6.7. This study provided evience for ethylene involvement in lettuce germination at supraoptimal temperature.