Seed aging affects ethylene production and endo--mannanase activity during lettuce seed germination at high temperature

2005 ◽  
Vol 33 (1) ◽  
pp. 11-17 ◽  
Author(s):  
W.M. Nascimento ◽  
D.J. Cantliffe ◽  
D.J. Huber
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Ethylene Production ◽  
Lettuce Seed ◽  
Seed Aging ◽  
Mannanase Activity ◽  
Lettuce Seed Germination

scholarly journals 402 Lettuce Seed Germination and Endo-mannanase Activity are Stimulated by Ethylene at High Temperature

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 513B-513 ◽  
Author(s):  
Warley M. Nascimento ◽  
Daniel J. Cantliffe ◽  
Donald J. Huber
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Enzyme Regulation ◽  
Seed Priming ◽  
Lettuce Seed ◽  
Endosperm Cell ◽  
Lettuce Seeds ◽  
Mannanase Activity ◽  
Lettuce Seed Germination

Temperatures above 30 °C may delay or inhibit germination of most of commercial lettuce cultivars. Ethylene enhances lettuce seed germination at high temperatures. Enzyme-mediated degradation of endosperm cell walls appears to be a crucial factor for lettuce germination at high temperature. The galactomannan polysaccharides in lettuce endosperm cell wall are mobilized by endomannanase. The role of endo-mannanase during germination of lettuce seeds at high temperature (35 °C) and the possible role of etlene in enzyme regulation were investigated. Seeds of thermotolerant (`Everglades'-EVE) and thermosensitive (`Dark Green Boston'-DGB) lettuce genotypes were incubated at 20 and 35 °C in water, 10 mM of 1-aminocyclopropane-1-carboxylic acid (ACC), or 20 mM of silver thiosulphate (STS). Also, seeds were primed in an aerated solution of polyethylene glycol (PEG), or PEG+ACC, or PEG+STS. Untreated seeds germinated 100% at 20 °C. At 35 °C, EVE germinated 100%, whereas DGB germinated only 33%. Seed priming or adding ACC during imbibition increased germination of DGB to 100% at 35 °C. Adding STS during imbibition led to a decrease in germination at 35%C in EVE and completely inhibited germination of DGB. Priming with STS led to reduced germination at 35%C of both genotypes. EVE produced more ethylene than DGB during germination at high temperature. Providing ACC either during priming or during germination led to an increase in endo-mannanase activity, whereas STS inhibited mannanase activity. Higher endo-mannana activity was observed in EVE than DGB seeds. The results suggest that ethylene might overcome the inhibitory effect of high temperature in thermosensitive lettuce seeds via weakening of endosperm due to increased endo-mannanase activity.

scholarly journals Ethylene evolution and endo-beta-mannanase activity during lettuce seed germination at high temperature

2004 ◽  
Vol 61 (2) ◽  
pp. 156-163 ◽  
Author(s):  
Warley Marcos Nascimento ◽  
Daniel James Cantliffe ◽  
Donald John Huber
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Seed Priming ◽  
Inhibitory Effect ◽  
Lettuce Seed ◽  
Ethylene Evolution ◽  
Radicle Protrusion ◽  
Mannanase Activity ◽  
Lettuce Seed Germination ◽  
Dark Green

High temperatures during lettuce seed imbibition can delay or completely inhibit germination and the endosperm layer appears to restrict the radicle protrusion. The role of endo-beta-mannanase during lettuce seed germination at 35°C and the influence of ethylene in endo-beta-mannanase regulation were investigated. Seeds of 'Dark Green Boston' (DGB) and 'Everglades' (EVE) were germinated in water, or 10 mmol L-1 of 1-aminocyclopropane-1-carboxylic acid (ACC), or 10 mmol L-1 of aminoethoxyvinylglycine (AVG), or 20 mmol L-1 of silver thiosulphate (STS). Seeds were also primed in polyethylene glycol (PEG), or PEG + ACC, PEG + AVG, or PEG + STS. Untreated seeds germinated 100% at 20°C. At 35°C, EVE seeds germinated 100%, whereas DGB seeds germinated only 33%. Seed priming or adding ACC during incubation increased germination at 35°C. Higher ethylene evolution was detected in EVE than in DGB during germination at 35°C. AVG did not inhibit seed germination of DGB at 35°C, but STS did. Higher endo-beta-mannanase activity was observed in EVE compared with DGB seeds. Providing ACC either during priming or during germination increased endo-beta-mannanase activity, whereas AVG and STS led to decreased or no activity. Ethylene may overcome the inhibitory effect of high temperature in thermosensitive lettuce seeds due to increased endo-beta-mannanase, possibly leading to weakening of the endosperm.

scholarly journals Structural Changes in Lettuce Seed during Germination Altered by Genotype, Seed Maturation Temperature, and Priming

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 526E-527
Author(s):  
Yu Sung ◽  
Daniel J. Cantliffe ◽  
Russell T. Nagata
Keyword(s):  
Cell Wall ◽  
High Temperature ◽  
Seed Germination ◽  
Structural Changes ◽  
Anatomical Study ◽  
Seed Maturation ◽  
Mechanical Resistance ◽  
Lettuce Seed ◽  
Endosperm Cell ◽  
Lettuce Seed Germination

Thermotolerance in lettuce seed at high temperature was investigated using primed and nonprimed seed or seeds matured at 20/10°C and 30/20°C. During seed germination at 36°C, the structural changes of the seed coverings in front of the radicle tip were observed in an anatomical study. In all seeds during imbibition, regardless of seed maturation temperature or priming, a crack appeared on one side of the cap tissue and the endosperm separated from the integument in front of the radicle tip. Additional changes took place during imbibition: the protein bodies in the vacuoles enlarged and were gradually depleted, large empty vacuoles formed, the cytoplasm condensed, the endosperm shrank, the endosperm cell wall dissolved and ruptured, then the radicle elongated toward this ruptured area. The findings suggested that the papery endosperm layer presented mechanical resistance to lettuce seed germination and the weakening of this layer was a prerequisite to radicle protrusion at high temperature. Seeds of `Dark Green Boston', `Everglades', and PI 251245 matured at 30/20°C had greater thermotolerance than those matured at 20/10°C. Results of the anatomical study indicated that the endosperm cell walls in front of the radicle of seeds matured at 30/20°C were more easily disrupted and ruptured during early imbibition than seeds matured at 20/10°C, suggesting that these seeds could germinate quickly at supra-optimal temperatures. From anatomical studies conducted to identify and characterize thermotolerance in lettuce seed germination, it was observed that genotype thermotolerance had the ability to reduce physical resistance of the endosperm by weakening the cell wall and by depleting stored reserves.

scholarly journals Ethylene and lettuce seed germination

2003 ◽  
Vol 60 (3) ◽  
pp. 601-606 ◽  
Author(s):  
Warley Marcos Nascimento
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Critical Factor ◽  
Inhibitory Effect ◽  
Lettuce Seed ◽  
A Cell ◽  
Lettuce Seed Germination ◽  
Exogenous Ethylene ◽  
Increased Activity

Ethylene can stimulate seed germination and overcome dormancy in many species. For instance, the inhibitory effect of high temperature on lettuce seed germination can be overcome by exogenous ethylene. Involvement of ethylene in seed germination is a widely accepted fact, but the mechanistic details are poorly understood. A critical factor in ethylene studies is the response of seed germination properties to various ethylene inhibitors. Lettuce seed has been used as a model to study the role of ethylene in seed germination at high temperature. The role of ethylene in germination is not known but either ethylene evolution or addition of 1-aminocyclopropane-1-carboxilic acid (ACC) have been associated with increased activity of endo-beta-mannanase, a cell-wall enzyme that weakens the endosperm and allows lettuce seed to germinate at high temperature. This review describes some results on seed germination studies in response to ethylene and its possible role in promoting germination at high temperature.

scholarly journals Thermotolerance in Lettuce Seeds: Association with Ethylene and Endo-β-mannanase

2000 ◽  
Vol 125 (4) ◽  
pp. 518-524 ◽  
Author(s):  
Warley M. Nascimento ◽  
Daniel J. Cantliffe ◽  
Donald J. Huber
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Ethylene Production ◽  
Potential Role ◽  
Endosperm Tissue ◽  
Lettuce Seeds ◽  
Radicle Protrusion ◽  
Mannanase Activity ◽  
Dark Green

Weakening of the endosperm tissue around the radicle tip before radicle protrusion and a potential role of endo-β-mannanase during germination of lettuce seeds (Lactuca sativa L.) at high temperature (35 °C) were investigated. Seeds from the thermotolerant genotypes `Everglades' and PI 251245 had greater endo-β-mannanase activity before radicle protrusion at 35 °C than the thermosensitive genotypes `Dark Green Boston', `Valmaine' and `Floricos 83'. Thermotolerant genotypes also generated more ethylene at high temperature. At 35 °C, germination of `Dark Green Boston' and `Everglades' seeds produced at days/nights of 20/10 °C was 10% and 32%, respectively, whereas germination of seeds produced at days/nights of 30/20 °C was 67% and 83%, respectively. Higher endo-β-mannanase activity was observed before radicle protrusion in `Dark Green Boston' seeds produced at 30/20 °C compared with those produced at 20/10 °C. A relationship between seed germination at high temperature, ethylene production, and an increase in endo-β-mannanase activity before radicle protrusion was confirmed.

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