Gibberellins and Seed Development in Maize. I. Evidence That Gibberellin/Abscisic Acid Balance Governs Germination versus Maturation Pathways

White, Constance; Proebsting, William M.; Hedden, Peter; Rivin, Carol J.

doi:10.1104/pp.122.4.1081

Cited by 207 publications

(136 citation statements)

References 41 publications

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“…The inhibition of de novo ABA biosynthesis by fluridone in the newly formed leaves of these plants caused a complete break of leaf embryo dormancy and induced their "germination." Our results are in agreement with two other reports, which showed that the applications of fluridone to developing embryos, before the increase of endogenous ABA levels, prevented both ABA accumulation and development of embryo dormancy (Fong et al, 1983;White et al, 2000). On the other hand, none of the exogenous ABA applications could aggravate the transgenic dormant seed-like phenotype, nor did they affect normal wildtype leaf embryo development (data not shown).…”

Section: Discussionsupporting

confidence: 83%

“…This indicates that ABA alone is not sufficient to induce dormancy to K. daigremontiana leaf embryos. In fact, the ABA-deficient maize mutant kernels are viviparous and precociously germinate in spite of a large contribution of ABA from the maternal plant (White et al, 2000). These results have led to the supposition that a threshold level of ABA at the appropriate time is required to block viviparous development (Fong et al, 1983;White et al, 2000).…”

Section: Discussionmentioning

confidence: 96%

“…Interestingly, ABA applications failed to aggravate the transgenic dormant seed-like phenotype and did not affect normal wild-type plantlet development (data not shown). One explanation for this result is that the window of developmental time during which ABA can impose dormancy is narrow and was missed during our experiments (Fong et al, 1983;White et al, 2000).…”

Section: Functional Kdlec1 Gene Is Expressed In Transgenic Leaf Marginsmentioning

confidence: 92%

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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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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 96%

Section: Functional Kdlec1 Gene Is Expressed In Transgenic Leaf Marginsmentioning

confidence: 92%

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

et al. 2014

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“…These include ABA/stressinducible proteins, heat shock proteins, late embryogenesis abundant (LEA) proteins, and proteases (Yacoob and Filion, 1986;Prasad, 1996;Nieto-Sotelo et al, 1999;White et al, 2000). Upon comparing the accession numbers of drought and cold-induced genes in Arabidopsis reported by Seki et al (2001) with the differentially expressed genes in this study (Tables I-IV), we found none of the genes to be in common.…”

Section: Differentially Expressed Genesmentioning

confidence: 92%

Expression Profiling of Reciprocal Maize Hybrids Divergent for Cold Germination and Desiccation Tolerance

et al. 2002

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Recombinant inbred lines (RILs) derived from B73 ϫ M017 were screened for cold germination (CG) and desiccation tolerance (DT) phenotypes. Reciprocal F 1 hybrids were made between divergent RILs, and hybrids that showed differential phenotypes (parent-of-origin effect) for CG or DT were selected for profiling mRNA and protein expression. mRNA and proteins were extracted from embryo axes of seed germinated for 11 d at 12.5°C in the dark and developing embryos at 40% seed moisture (R5 stage) for CG and DT, respectively. GeneCalling analysis, an open-ended mRNA profiling method, identified 336 of 32,496 and 656 of 32,940 cDNA fragments that showed Ն1.5-fold change in expression between the reciprocal F 1 hybrids for CG and DT, respectively. Protein expression map (PEM) analysis, an open-ended two-dimensional polyacrylamide gel electrophoresis, identified 117 of 2,641 and 205 of 1,876 detected proteins to be differentially expressed with Ն1.5-fold change between the reciprocal F 1 hybrids in CG and DT samples, respectively. A subset of these proteins was identified by tandem mass spectrometry followed by database query of the spectra. The differentially expressed genes/ proteins were classified into various functional groups including carbohydrate and amino acid metabolism, ion transporters, stress and defense response, polyamine metabolism, chaperonins, cytoskeleton associated, etc. Phenotypic analysis of seed from self-pollinated ears of the reciprocal F 1 hybrids displayed small differences compared with the reciprocal hybrids themselves, suggesting a negligible effect of cytoplasmic factors on CG and DT traits. The results provide leads to improving our understanding of the genes involved in stress response during seed maturation and germination.

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“…The current theory of ABA/GAs antagonism in seed germination is based on experiments showing that ABA-deficient and ABAinsensitive mutants rescue the germination of the ga1 GA-deficient mutant and of seeds treated with GA biosynthetic inhibitor (Koornneef et al, 1982;Nambara et al, 1991;Leon-Kloosterziel et al, 1996). In maize (Zea mays), the ABA/GAs balance also governs seed development, as GA deficiency early in seed development suppresses precocious germination in ABA-deficient developing kernels and bioactive GA species accumulate prior to the peak in ABA content (White et al, 2000). While ABA biosynthesis is regulated both maternally and zygotically, the control of GA biosynthesis during seed development is largely unknown.…”

mentioning

confidence: 99%

AtGA3ox2, a Key Gene Responsible for Bioactive Gibberellin Biosynthesis, Is Regulated during Embryogenesis by LEAFY COTYLEDON2 and FUSCA3 in Arabidopsis

et al. 2004

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Embryonic regulators LEC2 (LEAFY COTYLEDON2) and FUS3 (FUSCA3) are involved in multiple aspects of Arabidopsis (Arabidopsis thaliana) seed development, including repression of leaf traits and premature germination and activation of seed storage protein genes. In this study, we show that gibberellin (GA) hormone biosynthesis is regulated by LEC2 and FUS3 pathways. The level of bioactive GAs is increased in immature seeds of lec2 and fus3 mutants relative to wild-type level. In addition, we show that the formation of ectopic trichome cells on lec2 and fus3 embryos is a GA-dependent process as in true leaves, suggesting that the GA pathway is misactivated in embryonic mutants. We next demonstrate that the GA-biosynthesis gene AtGA3ox2, which encodes the key enzyme AtGA3ox2 that catalyzes the conversion of inactive to bioactive GAs, is ectopically activated in embryos of the two mutants. Interestingly, both b-glucuronidase reporter gene expression and in situ hybridization indicate that FUS3 represses AtGA3ox2 expression mainly in epidermal cells of embryo axis, which is distinct from AtGA3ox2 pattern at germination. Finally, we show that the FUS3 protein physically interacts with two RY elements (CATGCATG) present in the AtGA3ox2 promoter. This work suggests that GA biosynthesis is directly controlled by embryonic regulators during Arabidopsis embryonic development.Higher plant embryogenesis is divided into two major phases: embryo development (or morphogenesis) and seed maturation (West and Harada, 1993). During embryo development, early morphogenetic processes occur that give rise to embryonic cell types, tissues, and organs. During seed maturation, the fully developed embryo undergoes maturation, during which food reserves accumulate and dormancy and desiccation tolerance develop.Seed development has been extensively studied in Arabidopsis (Arabidopsis thaliana) using mutants defective either in morphogenesis, such as GNOM (Mayer et al., 1991;Shevell et al., 1994) or KNOLLE (Mayer et al., 1991;Lukowitz et al., 1996), or in maturation, such as ABI (ABSCISIC ACID-INSENSITIVE) loci that were initially identified on the basis of the abscisic acid (ABA) hormone-resistant germination of mutants at these loci (Koornneef et al., 1984;Giraudat et al., 1992;Finkelstein et al., 1998;Finkelstein and Lynch, 2000). A particular set of mutants exhibiting the lec phenotype, which consists of a partial transformation of cotyledons into leaves, has allowed the identification of an important network of regulatory genes. The LEC1 (LEAFY COTYLEDON1; Meinke, 1992), LEC2 (Meinke et al., 1994), and FUS3 (FUSCA3;Keith et al., 1994;Meinke et al., 1994) genes, which are defined as the LEC genes hereafter, are the only known regulators required for normal development during both the morphogenesis and the maturation phases (Holdsworth et al., 1999;Harada, 2001 Article, publication date, and citation information can be found at www.plantphysiol.org/cgi

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Gibberellins and Seed Development in Maize. I. Evidence That Gibberellin/Abscisic Acid Balance Governs Germination versus Maturation Pathways

Cited by 207 publications

References 41 publications

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

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

Expression Profiling of Reciprocal Maize Hybrids Divergent for Cold Germination and Desiccation Tolerance

AtGA3ox2, a Key Gene Responsible for Bioactive Gibberellin Biosynthesis, Is Regulated during Embryogenesis by LEAFY COTYLEDON2 and FUSCA3 in Arabidopsis

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