Relationship of Ethylene Production to Stress Alleviation in Seeds of Lettuce Cultivars

Abstract

<jats:p>Seeds (intact or slit) of lettuce <jats:italic>(Luctuca sativa</jats:italic> L.) cultivars with greater ability to produce ethylene germinated better under stressful conditions. Highly significant correlations were found between ethylene production and germination in 0.1 <jats:sc>m</jats:sc> NaCI (- 0.49 MPa) solution at 25C <jats:italic>(r =</jats:italic> 0.95, intact seeds), in - 0.3 MPa PEG solution <jats:italic>(r =</jats:italic> 0.86, intact seeds; <jats:italic>r =</jats:italic> 0.81, slit seeds), and in water at 32C (r = 0.80, slit seeds) or 35C <jats:italic>(r =</jats:italic> 0.80, slit seeds). Slitting the seed coat increased the ethylene production and improved germination during osmotic restraint in most cultivars, particularly in `Mesa 659' and `Super 59'. The differing ability of cultivars to produce ethylene during stress generally corresponded with their ability to generate germination potential. Ethylene production and germination potential in untreated and ACC-treated `Mesa 659' seeds increased upon slitting under stressful conditions. Thus, the ability of seeds to produce ethylene and to generate high germination potential under stressful conditions may be used as criteria to select stress-tolerant lettuce cultivars. Chemical names used: polyethylene glycol 8000 (PEG), 1-aminocyclopropane-1-carboxylic acid (ACC), (2-chlorethyl) phosphoric acid (ethephon).</jats:p>

ABA crosstalk with ethylene and nitric oxide in seed dormancy and germination

“…Incubation at high temperature (35°C) of lettuce seeds induces a reduction in ethylene production (Prusinski and Khan, 1990), associated with a complete repression of LsACS1 and a reduced expression of ACO-A (homologous to AtACO4 ; Argyris et al, 2008). …”

Germination of Senna Occidentalis link: seed at different osmotic potential levels

“…Water stress acts by decreasing the percentage and rate of germination (Prusinski and Khan, 1990;Branccini et al, 1996), and for each species there exists a value of water potential below which germination does not occur (Bewley and Black, 1985). In order for the process of germination to start, it is necessary for the seed to reach an adequate level of hydration, which will permit a reactivation of the metabolic processes (Cordoba et al, 1995).…”

High Temperature Inhibits Germination of Jalapeño and Cayenne Pepper

“…, but again gemination dropped to 1% at 40°C (data not shown). Cultivar differences in germination response to temperature have been reported in lettuce (Perkins-Veazie and Cantliffe, 1984;Prusinski and Khan, 1990;Thompson et al, 1979) and spinach (Atherton and Farooque, 1983;Leskovar et al, 1999). Germination of 'Packman' broccoli (Brassica oleracea L., Botrytis group) decreased from 90% to 63% at 35 °C when the germination of this cultivar was tested at a range between 5 and 40 °C (Elson et al, 1992).…”