Involvement of Endogenous Abscisic Acid in Onset and Release of <i>Helianthus annuus</i> Embryo Dormancy

Page-Degivry, Marie-Thérèse Le; Barthe, Philippe; Garello, G.

doi:10.1104/pp.92.4.1164

Cited by 78 publications

(35 citation statements)

References 10 publications

(7 reference statements)

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“…Again, because it is unlikely that this inhibition occurs because of direct ABA action, it will be an extended result of ABA action during seed development, which may interfere with GA production, transport, or sensitivity. Studies with A. thaliana (12) and H. annuus (14) support the hypothesis that dormancy is related to decreased GA sensitivity. Seed of ABA-deficient lines of Arabidopsis were 100-fold more sensitive to GA4+7 than ABA-producing lines, and preincubation in water of dormant Helianthus embryos resulted in both an increase of the sensitivity to GA and a relief of dormancy.…”

Section: Maintenance Of Dormancysupporting

confidence: 53%

See 1 more Smart Citation

Dormancy and Germination of Abscisic Acid-Deficient Tomato Seeds

Groot¹,

Karssen²

1992

Plant Physiol.

184

120

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The role of abscisic acid (ABA) in the dormancy induction of tomato (Lycopersicon esculentum) seeds was studied by comparison of the germination behavior of the ABA-deficient sitiens mutant with that of the isogenic wild-type genotype. Freshly harvested mutant seeds, in contrast to wild-type seeds, always readily germinate and even exhibit viviparous germination in overripe fruits. Crosses between mutant and wild-type and self-pollination of heterozygous plants show that in particular the ABA fraction of embryo and endosperm is decisive for the induction of dormancy. After-ripened wild-type seeds fully germinate in water but are more sensitive toward osmotic inhibition than mutant seeds. Germination of both wild-type and mutant seeds is equally sensitive toward inhibition by exogenous ABA. ABA content of mature wildtype seeds is about 10-fold the level found in mutant seeds. Nevertheless, it is argued that the differences in dormancy between the seeds of both genotypes are not a result of actual ABA levels in the mature seeds or fruits but a result of differences in ABA levels during seed development. It is hypothesized that the high levels of ABA that occur during seed development in wild-type seeds induce an inhibition of cell elongation of the radicle that can still be observed after long periods of dry storage.Studies with ABA-deficient mutants of Arabidopsis thaliana provided clear evidence that the induction of dormancy during the development of seeds on the mother plant depends on an increase of endogenous ABA (11 the mature seed (12). Bonamy and Dennis (1) showed that in mature peach seeds the ABA level diminished much more rapidly during incubation at 20 than at 50C, whereas dormancy was only relieved at 50C.It was the aim of the present study to test whether the hypothesis formulated for seeds of A. thaliana also holds for tomato (Lycopersicon esculentum) seeds. The experiments were performed with the sitiens (sitw) mutant of cv Moneymaker, isolated and phenotypically characterized by Koomneef et al. (13). It was shown before that developing sit' seeds contain about 3% of the ABA level in wild-type seeds (8). The strong reduction of ABA levels did not show significant influence on seed development. From our present work, however, we have found that the mutation caused vivipary and lack of dormancy in ripe and mature seeds. An attempt will be made to characterize and localize the ABA-induced dormancy.Compared to the tiny seeds of A. thaliana, the relatively large seeds of tomato are better objects for a study of the localization of hormone action in the different seed parts during development and germination. Previous experiments with the GA3-deficient gib-i mutant of tomato (in those studies still denoted as ga-1) have shown that endogenous GA promotes tomato seed germination by induction of cell wall-hydrolyzing enzymes in the endosperm, thereby facilitating a weakening of the mechanical restraint of the endosperm region opposing the radicle tip (6, 7). We will study whether the direct or indi...

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Section: Maintenance Of Dormancysupporting

confidence: 53%

“…Recently, Le Page-Degivry et al (14) demonstrated that application of fluridone caused a strong reduction of ABA levels and prevented the development of embryo dormancy in developing seeds of Helianthus anuus.…”

mentioning

confidence: 99%

Dormancy and Germination of Abscisic Acid-Deficient Tomato Seeds

Groot¹,

Karssen²

1992

Plant Physiol.

184

120

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“…7E, L2) of the same plant. This is consistent with the fluridone effect on seed embryo dormancy breaking prior to ABA accumulation (Fong et al, 1983;Le Page-Degivry et al, 1990;Yoshioka et al, 1998). While fluridone is known to have multiple pleiotropic effects on the plant, our results show that fluridone can restore normal plantlet development, likely due to systemic ABA biosynthesis inhibition prior to its accumulation.…”

Section: Functional Kdlec1 Gene Is Expressed In Transgenic Leaf Marginssupporting

confidence: 74%

Truncation of LEAFY COTYLEDON1 Protein Is Required for Asexual Reproduction in Kalanchoë daigremontiana

et al. 2014

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Kalanchoë daigremontiana reproduces asexually by generating numerous plantlets on its leaf margins. The formation of plantlets requires the somatic initiation of organogenic and embryogenic developmental programs in the leaves. However, unlike normal embryogenesis in seeds, leaf somatic embryogenesis bypasses seed dormancy to form viable plantlets. In Arabidopsis (Arabidopsis thaliana), seed dormancy and embryogenesis are initiated by the transcription factor LEAFY COTYLEDON1 (LEC1). The K. daigremontiana ortholog of LEC1 is expressed during leaf somatic embryo development. However, KdLEC1 encodes for a LEC1-type protein that has a unique B domain, with 11 unique amino acids and a premature stop codon. Moreover, the truncated KdLEC1 protein is not functional in Arabidopsis. Here, we show that K. daigremontiana transgenic plants expressing a functional, chimeric KdLEC1 gene under the control of Arabidopsis LEC1 promoter caused several developmental defects to leaf somatic embryos, including seed dormancy characteristics. The dormant plantlets also behaved as typical dormant seeds. Transgenic plantlets accumulated oil bodies and responded to the abscisic acid biosynthesis inhibitor fluridone, which broke somatic-embryo dormancy and promoted their normal development. Our results indicate that having a mutated form of LEC1 gene in K. daigremontiana is essential to bypass dormancy in the leaf embryos and generate viable plantlets, suggesting that the loss of a functional LEC1 promotes viviparous leaf somatic embryos and thus enhances vegetative propagation in K. daigremontiana. Mutations resulting in truncated LEC1 proteins may have been of a selective advantage in creating somatic propagules, because such mutations occurred independently in several Kalanchoë species, which form plantlets constitutively.

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“…When ABA was applied to young nondormant embryos (7)(8)(9)(10), it inhibited germination as long as it was present. However, whatever the dose used ( and the duration ofits application (5 or 10 d) ABA was unable to induce dormancy since after transfer on control medium, germination occurred ( Figs.…”

Section: Responsiveness Of Young Nondormant Embryos To Exogenous Abamentioning

confidence: 99%

In Situ Abscisic Acid Synthesis

Page-Degivry¹,

Garello²

1992

Plant Physiol.

Self Cite

110

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When applied to young nondormant embryos of sunflower (Helianthus annus) (7-10 day[s] after pollination [DAP]), abscisic acid (ABA) inhibited germination as long as it was present. However, whatever the dose used and the duration of its application, ABA was unable to induce dormancy because after transfer of treated embryos to control (without ABA) medium, germination occurred. Thereafter, exogenous ABA became effective and allowed the dormancy to develop in 13 and 17 DAP embryos, i.e. in embryos which after isolation were still able to germinate in high percentage. After embryo dormancy was well established (21 DAP), application of fluridone allowed the germination to occur very quickly on control medium. Isolated dormant axes were also induced to germinate by an application of fluridone. Radioimmunological analysis showed that 24 hours after these treatments, endogenous ABA levels were drastically reduced in the axes. When these fluridone-treated embryos were cultured on ABA medium, germination was again inhibited as long as exogenous ABA was present but germination occurred as soon as embryos were transferred to control medium. Such behavior suggested that in situ ABA synthesis is necessary to impose and maintain the embryo dormancy.The involvement ofABA in the initiation ofseed dormancy has been the subject of many recent studies using either mutants deficient in or insensitive to the hormone (4-6) or inhibitors of synthesis, particularly fluridone (3,11,12 embryos isolated at various times after pollination to exogenous ABA. It seemed necessary to distinguish clearly between the physiological consequences of the presence of exogenous ABA in the culture medium and those associated with a genuine induction effect, that is to say those produced by transient application of the hormone and which subsequently persist in its absence. Furthermore, we studied the consequences of an application of fluridone to isolated dormant embryos on their physiological behavior, their endogenous ABA levels and their responsiveness to exogenous ABA. MATERIALS AND METHODS Plant MaterialPlants of sunflower (Helianthus annuus cv Mirasol) were grown in the fields during summer. In September, flowers of male sterile plants were manually pollinated by pollen harvested on small female sterile flowers (seeds generously provided by S.A. Cargill). Flowers were tagged and harvest took place at different times after pollination.For each age, 25 embryos, i.e. a sample considered as sufficient to be representative of the population, were used for in vitro culture and extraction. All the experiments were carried out two or three times in two different years (1989)(1990).

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Involvement of Endogenous Abscisic Acid in Onset and Release of Helianthus annuus Embryo Dormancy

Cited by 78 publications

References 10 publications

Dormancy and Germination of Abscisic Acid-Deficient Tomato Seeds

Dormancy and Germination of Abscisic Acid-Deficient Tomato Seeds

Truncation of LEAFY COTYLEDON1 Protein Is Required for Asexual Reproduction in Kalanchoë daigremontiana

In Situ Abscisic Acid Synthesis

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