Article

Roles of gibberellins and abscisic acid in dormancy and germination of red bayberry (Myrica rubra) seeds

Division of Forest Biology, Taiwan Forestry Research Institute, Taipei 10066, Taiwan.
Tree Physiology (Impact Factor: 3.41). 09/2008; 28(9):1431-9. DOI: 10.1093/treephys/28.9.1431
Source: PubMed

ABSTRACT Intact seeds from freshly harvested fruits of Myrica rubra (Sieb et Zucc.) were dormant and required 8 weeks of warm stratification followed by 12 weeks of cold stratification for germination. Exogenous application of gibberellic acid (GA(3)) to intact fresh seeds was effective in breaking dormancy, with > 70% of seeds germinating when treated with 5.2 mM GA(3) and incubated at a day/night temperature of 30/20 degrees C for 20 weeks. Removing the hard endocarp or endocarp plus seed coat of fresh seeds promoted germination, and addition of GA(3) to the embryo accelerated germination. The gibberellins GA(1) and GA(4) were more effective than GA(3) in promoting germination of seeds with the endocarp removed. Endogenous contents of GA(1), GA(3), GA(4), GA(7) and GA(20) were quantified by gas chromatography-mass spectrometry-selected ion monitoring in the endocarps, seed coats and embryos of fresh seeds treated with 5.2 mM GA(3). The content of GA(3) decreased in the endocarp during incubation, whereas GA(1) contents increased in the endocarp and seed coat. A high GA(1) content was detected in the endocarps and embryos of newly germinated seeds. We speculate that GA(3) was converted to GA(1) during incubation and that GA(1) is involved in seed germination. Endogenous abscisic acid (ABA) contents were measured in fresh seeds and in warm and cold stratified seeds. The ABA content in fresh seeds was distributed in the order endocarp > seed coat > embryo, with the content in the endocarp being about 132-fold higher than in the seed coat and embryo. Total ABA content of seeds subjected to warm or cold stratification, or both, was 8.7- to 14.0-fold lower than that of fresh seeds. Low contents of endogenous GA(1), GA(3), GA(7) and GA(20), but elevated contents of GA(4), were found in the seed coats and endocarps of warm plus cold stratified seeds and in the seed coats and embryos of newly germinated seeds. These observations, coupled with the finding that GA stimulated germination of dormant Myrica seeds, provide evidence that endogenous ABA inhibited release of dormancy and that endogenous gibberellins, especially GA(4) or GA(1), or both, are involved in germination.

Download full-text

Full-text

Available from: Ching-Te Chien, Nov 12, 2014
1 Follower
 · 
354 Views
    • "Fresh seeds and those cold-stratified for 4, 8 and 12 weeks as well as radicle-emerged seeds were used in the analyses; there were three replications of each sample (about 200 mg dry sample). The methods for extracting and quantifying ABA, GA 1 , GA 3 , GA 4 , GA 7 and GA 20 in the tissues have been described by Nakayama et al. (2001) and Chen et al. (2008). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Breaking of seed dormancy by moist cold stratification involves complex interactions in cells. To assess the effect of moist cold stratification on dormancy break in seeds of Acer morrisonense, we monitored percentages and rates of germination and changes in plant growth regulators, sugars, amino acids and embryo ultrastructure after various periods of cold stratification. Fresh seeds incubated at 25/15 °C for 24 weeks germinated to 61%, while those cold stratified at 5 °C for 12 weeks germinated to 87% in 1 week. Neither exogenous GA3 nor GA4 pretreatment significantly increased final seed germination percentage. Total ABA content of seeds cold stratified for 12 weeks was reduced about 3.3-fold, to a concentration similar to that in germinated seeds (radicle emergence). Endogenous GA3 and GA7 were detected in 8-week and 12-week cold stratified seeds but not in fresh seeds. Numerous protein and lipid bodies were present in the plumule, first true leaves and cotyledons of fresh seeds. Protein and lipid bodies decreased greatly during cold stratification, and concentrations of total soluble sugars and amino acids increased. The major non-polar sugars in fresh seeds were sucrose and fructose, but sucrose increased and fructose decreased significantly during cold stratification. The major free amino acids were proline and tryptophan in fresh seeds, and proline increased and tryptophan decreased during cold stratification. Thus, as dormancy break occurs during cold stratification seeds of A. morrisonense undergo changes in plant growth regulators, proteins, lipids, sugars, amino acids and cell ultrastructure. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
    Plant Physiology and Biochemistry 06/2015; 94:165-173. DOI:10.1016/j.plaphy.2015.06.004 · 2.35 Impact Factor
  • Source
    • "The enhancing effect of gibberellins in light conditions on germination at constant temperatures reflects the fact that sensitivity to gibberellins is controlled by temperature (Toh et al., 2008). The fact that gibberellins induced high germination (>90%) at constant temperatures of 20 • C or 25 • C suggests that gibberellins increased the growth embryo potential, reducing the constraint of the seed covers (Chen et al., 2008). Additionally, temperature fluctuations were replaced by gibberellins confirming that temperature is the main factor that breaks dormancy in nature (Baskin and Baskin, 2014). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Species of the genus Hypericum have elicited great interest in pharmacological research, therefore their propagation is necessary. However, only a low germination percentage has been achieved to date. A population of Hypericum philonotis (Cham. & Schlecht.) grows every 2 or 5 years in the Parque Ecológico de la Ciudad de México (PECM). To understand seed germination and the population dynamics of H. philonotis in the PECM, we studied their seed germination to identify the dormancy type. We assessed the effect on germination of light, constant temperatures (5−35 °C) and fluctuating (25/35 °C, 18/6 h, with the highest temperature at noon, photoperiod 12/12), cold stratification, scarification (with HCl); gibberellins and seed immersion in acetone or hexane. We also studied the morphology and structure of the seeds, and the allelopathic potential of the pigments present in the seed coat on its own seed germination and early seedling growth. Light, gibberellins, a combination of temperature with gibberellins, and immersion in acetone increased seed germination. Alternating temperatures replaced the effect of gibberellins. Immersion in acetone eliminated a pigment from the seed coat, enhancing full seed germination. The acetone extract from H. philonotis seeds partially inhibited seed germination and early growth. The endosperm was reduced, and the main reserve in cotyledons was proteins. The H. philonotis seeds exhibited physiological dormancy. Gibberellins increased the embryo growth potential, reducing the constraint of the thick seed cover and any inhibiting effect of the acetone extract. The requirement of light and temperature fluctuation acts as an environmental cue for the successful germination of these minuscule seeds (0.5−0.8 mm in length).
    Flora - Morphology Distribution Functional Ecology of Plants 04/2015; 213. DOI:10.1016/j.flora.2015.04.001 · 1.46 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Davood Eradatmand Asli, Alireza Houshmandfar and Anoosh Eghdami; Endogenous gibberellins and abscisic acid levels during grain development of durum wheat genotypes ABSTRACT Grain growth rate (GGR), gibberellins (GAs), and abscisic acid (ABA) levels were studied within developing grains of different durum wheat genotypes (Triticum durum L.) included HD 4713, HD 4530 and PDW 233. The plants were grown in a screen covered hall under otherwise natural conditions and secondary tillers were removed as they appeared. Grain dry matter accumulation, GAs including GA 1 , GA 3 and GA 4 , and also ABA levels were determined in ten labelled spikes which sampled five times, seven-day intervals started from seventh day after anthesis (DAA) up to 35 th DAA. The GAs and ABA levels were possessed in a sequence during early to middle phase of grain setting while the GGR was max. The new genotype of HD 4713 which had maximum amounts of both GAs and ABA produced a highest quantum of dry matter accumulation. The results suggest that GAs and ABA contents are important factors governing grain dry matter accumulation in different genotypes. Furthermore, it could be possible to improve grain weight by manipulating GAs and ABA levels in grain, especially during the early to middle stage of grain filling either through breeding or crop management.
Show more