Gibberellin Requirement for Arabidopsis Seed Germination Is Determined Both by Testa Characteristics and Embryonic Abscisic Acid

Debeaujon, Isabelle; Koornneef, M.

doi:10.1104/pp.122.2.415

Cited by 373 publications

(257 citation statements)

References 41 publications

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“…A model system of seed germination and dormancy was proposed from biochemical and molecular information using dicot plants. Germination is determined by the balance between the growth potential of the embryo and the mechanical resistance of the tissues covering the embryo (26)(27)(28)(29). However, the mechanistic basis of the effect of the genes encoding cell wall proteins and hydrolases on seed germination is not well understood.…”

Section: Discussionmentioning

confidence: 99%

Molecular identification of a major quantitative trait locus, qLTG3–1 , controlling low-temperature germinability in rice

Fujino¹,

Sekiguchi²,

Matsuda³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

273

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Tolerance to abiotic stress is an important agronomic trait in crops and is controlled by many genes, which are called quantitative trait loci (QTLs). Identification of these QTLs will contribute not only to the understanding of plant biology but also for plant breeding, to achieve stable crop production around the world. Previously, we mapped three QTLs controlling low-temperature tolerance at the germination stage (called low-temperature germinability). To understand the molecular basis of one of these QTLs, qLTG3-1 (quantitative trait locus for low-temperature germinability on chromosome 3), map-based cloning was performed, and this QTL was shown to be encoded by a protein of unknown function. The QTL qLTG3-1 is strongly expressed in the embryo during seed germination. Before and during seed germination, specific localization of beta-glucuronidase staining in the tissues covering the embryo, which involved the epiblast covering the coleoptile and the aleurone layer of the seed coat, was observed. Expression of qLTG3-1 was tightly associated with vacuolation of the tissues covering the embryo. This may cause tissue weakening, resulting in reduction of the mechanical resistance to the growth potential of the coleoptile. These phenomena are quite similar to the model system of seed germination presented by dicot plants, suggesting that this model may be conserved in both dicot and monocot plants.natural variation ͉ QTLs ͉ seed germination T he control of seed dormancy and germination is important for the adaptability of plants, and germination under favorable environmental conditions is needed for their survival. Seed dormancy and germination is a complex trait influenced by many genes and environmental conditions (1). In addition, the plant hormones gibberellin and abscisic acid (ABA) play important roles in the expression of seed dormancy and germination (2, 3).Strong seedling vigor under low temperatures is an important objective of rice breeding programs in direct-seeding cultivation methods in temperate rice-growing areas, at high altitudes in tropical and subtropical areas, and in areas with a cold irrigation water supply where low temperature induces retardation of early seedling growth. Germinability (germination rate) and early seedling growth are major components of seedling vigor. A wide range of phenotypic variation of low-temperature germinability was found in rice cultivars. Quantitative trait loci (QTL) analysis for low temperature germinability revealed that many genes control this trait (4-6). However, the molecular functions of the genes for these QTLs have not been identified.A QTL mapping approach is effective to detect genes controlling traits involved in seed germination. Under several kinds of stress, such as temperature, NaCl, and osmotic pressure, germination is delayed or inhibited. QTLs for the speed of germination may be important for germination in general and may not be affected by any kind of stress (7,8). QTLs for the speed of germination collocated with those of ABA sensitivity a...

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Section: Discussionmentioning

confidence: 99%

Molecular identification of a major quantitative trait locus, qLTG3–1 , controlling low-temperature germinability in rice

Fujino¹,

Sekiguchi²,

Matsuda³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

273

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“…GA acts as a positive regulator of Arabidopsis seed germination, and severely GA-deficient mutant seeds do not germinate because the embryos are not able to emerge through the seed coat (Koornneef and van der Veen, 1980;Debeaujon and Koornneef, 2000;Penfield et al, 2006). GA biosynthesis de novo is a prerequisite for germination because inhibitors of GA biosynthesis applied during imbibition effectively inhibit the process (Nambara et al, 1991;Derkx and Karssen, 1993).…”

Section: Seed Germinationmentioning

confidence: 99%

Genetic Analysis Reveals That C19-GA 2-Oxidation Is a Major Gibberellin Inactivation Pathway inArabidopsis

et al. 2008

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Bioactive hormone concentrations are regulated both at the level of hormone synthesis and through controlled inactivation. Based on the ubiquitous presence of 2β-hydroxylated gibberellins (GAs), a major inactivating pathway for the plant hormone GA seems to be via GA 2-oxidation. In this study, we used various approaches to determine the role of C19-GA 2-oxidation in regulating GA concentration and GA-responsive plant growth and development. We show that Arabidopsis thaliana has five C19-GA 2-oxidases, transcripts for one or more of which are present in all organs and at all stages of development examined. Expression of four of the five genes is subject to feed-forward regulation. By knocking out all five Arabidopsis C19-GA 2-oxidases, we show that C19-GA 2-oxidation limits bioactive GA content and regulates plant development at various stages during the plant life cycle: C19-GA 2-oxidases prevent seed germination in the absence of light and cold stimuli, delay the vegetative and floral phase transitions, limit the number of flowers produced per inflorescence, and suppress elongation of the pistil prior to fertilization. Under GA-limited conditions, further roles are revealed, such as limiting elongation of the main stem and side shoots. We conclude that C19-GA 2-oxidation is a major GA inactivation pathway regulating development in Arabidopsis.

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“…GA not only controls the floral transition but also acts as an ABA antagonist during germination (Debeaujon and Koornneef, 2000;Kucera et al, 2005). To investigate whether alterations in RD20 expression also impacted the sensitivity to exogenous ABA, we studied seed germination and postgermination growth of the different RD20 transgenic lines in the presence of increasing concentrations of ABA.…”

Section: Rd20 Affects Aba-dependent Germination and Seed Dormancymentioning

confidence: 99%

The Reductase Activity of the Arabidopsis Caleosin RESPONSIVE TO DESSICATION20 Mediates Gibberellin-Dependent Flowering Time, Abscisic Acid Sensitivity, and Tolerance to Oxidative Stress

et al. 2014

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Contrasting with the wealth of information available on the multiple roles of jasmonates in plant development and defense, knowledge about the functions and the biosynthesis of hydroxylated oxylipins remains scarce. By expressing the caleosin RESPONSIVE TO DESSICATION20 (RD20) in Saccharomyces cerevisiae, we show that the recombinant protein possesses an unusual peroxygenase activity with restricted specificity toward hydroperoxides of unsaturated fatty acid. Accordingly, Arabidopsis (Arabidopsis thaliana) plants overexpressing RD20 accumulate the product 13-hydroxy-9,11,15-octadecatrienoic acid, a linolenate-derived hydroxide. These plants exhibit elevated levels of reactive oxygen species (ROS) associated with early gibberellin-dependent flowering and abscisic acid hypersensitivity at seed germination. These phenotypes are dependent on the presence of active RD20, since they are abolished in the rd20 null mutant and in lines overexpressing RD20, in which peroxygenase was inactivated by a point mutation of a catalytic histidine residue. RD20 also confers tolerance against stress induced by Paraquat, Rose Bengal, heavy metal, and the synthetic auxins 1-naphthaleneacetic acid and 2,4-dichlorophenoxyacetic acid. Under oxidative stress, 13-hydroxy-9,11,15-octadecatrienoic acid still accumulates in RD20-overexpressing lines, but this lipid oxidation is associated with reduced ROS levels, minor cell death, and delayed floral transition. A model is discussed where the interplay between fatty acid hydroxides generated by RD20 and ROS is counteracted by ethylene during development in unstressed environments.

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Gibberellin Requirement for Arabidopsis Seed Germination Is Determined Both by Testa Characteristics and Embryonic Abscisic Acid

Cited by 373 publications

References 41 publications

Molecular identification of a major quantitative trait locus, qLTG3–1 , controlling low-temperature germinability in rice

Molecular identification of a major quantitative trait locus, qLTG3–1 , controlling low-temperature germinability in rice

Genetic Analysis Reveals That C19-GA 2-Oxidation Is a Major Gibberellin Inactivation Pathway inArabidopsis

The Reductase Activity of the Arabidopsis Caleosin RESPONSIVE TO DESSICATION20 Mediates Gibberellin-Dependent Flowering Time, Abscisic Acid Sensitivity, and Tolerance to Oxidative Stress

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