Key Role for Endogenous Gibberellins in the Control of Seed Germination

Karssen, C.M.; Zagórski, Slawomir; Kępczyński, Jan; Groot, S.P.C.

doi:10.1093/oxfordjournals.aob.a087730

Cited by 214 publications

(139 citation statements)

References 17 publications

Supporting

Mentioning

124

Contrasting

Unclassified

Order By: Relevance

“…), seeds of which will not germinate unless exogenously supplied with GAs (Koornneef and van der Veen, 1980;Groot and Karssen, 1987). Furthermore, the fact that inhibitors of GA biosynthesis such as paclobutrazol (PAC), uniconazol, and tetcyclacis prevent germination (Karssen et al, 1989;Nambara et al, 1991;Jacobsen and Olszewski, 1993) indicated the requirement for de novo synthesis of GAs in germination.…”

Section: Influence Of Gasmentioning

confidence: 99%

The Effect of α-Amanitin on the Arabidopsis Seed Proteome Highlights the Distinct Roles of Stored and Neosynthesized mRNAs during Germination

et al. 2004

View full text Add to dashboard Cite

To investigate the role of stored and neosynthesized mRNAs in seed germination, we examined the effect of a-amanitin, a transcriptional inhibitor targeting RNA polymerase II, on the germination of nondormant Arabidopsis seeds. We used transparent testa mutants, of which seed coat is highly permeable, to better ascertain that the drug can reach the embryo during seed imbibition. Even with the most permeable mutant (tt2-1), germination (radicle protrusion) occurred in the absence of transcription, while subsequent seedling growth was blocked. In contrast, germination was abolished in the presence of the translational inhibitor cycloheximide. Taken together, the results highlight the role of stored proteins and mRNAs for germination in Arabidopsis and show that in this species the potential for germination is largely programmed during the seed maturation process. The a-amanitin-resistant germination exhibited characteristic features. First, this germination was strongly slowed down, indicating that de novo transcription normally allows the synthesis of factor(s) activating the germination rate. Second, the sensitivity of germination to gibberellic acid was reduced 15-fold, confirming the role of this phytohormone in germination. Third, de novo synthesis of enzymes involved in reserve mobilization and resumption of metabolic activity was repressed, thus accounting for the failure in seedling establishment. Fourth, germinating seeds can recapitulate at least part of the seed maturation program, being capable of using mRNAs stored during development. Thus, commitment to germination and plant growth requires transcription of genes allowing the imbibed seed to discriminate between mRNAs to be utilized in germination and those to be destroyed.

show abstract

Section: Influence Of Gasmentioning

confidence: 99%

The Effect of α-Amanitin on the Arabidopsis Seed Proteome Highlights the Distinct Roles of Stored and Neosynthesized mRNAs during Germination

et al. 2004

View full text Add to dashboard Cite

show abstract

“…For example, since the original observation by Chrispeels and Varner (1966), it has been repeatedly shown that GA induces germination and that abscisic acid (ABA) antagonizes the GA effect (Koornneef and Van der Veen, 1980;Karssen et al, 1989;Gilroy and Jones, 1994;Ritchie and Gilroy, 1998;Lovegrove and Hooley, 2000). Seed germination of GA synthesis mutants can be rescued by the application of GA and ABA synthesis and insensitive mutants lack the ABA inhibition of GA-induced germination as well as being viviparous (Koornneef et al, 1982(Koornneef et al, , 1984Finkelstein and Somerville, 1990;Koornneef and Karssen, 1994;Leon-Kloosterziel et al, 1996).…”

mentioning

confidence: 99%

Role of a Heterotrimeric G Protein in Regulation of Arabidopsis Seed Germination

et al. 2002

View full text Add to dashboard Cite

Seed germination is regulated by many signals. We investigated the possible involvement of a heterotrimeric G protein complex in this signal regulation. Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA), have increased sensitivity to high levels of Glc, and have a near-wild-type germination response to abscisic acid and ethylene, indicating that GPA1 does not directly couple these signals in germination control. Seeds ectopically expressing GPA1 are at least a million-fold more responsive to GA, yet still require GA for germination. We conclude that the GPA1 indirectly operates on the GA pathway to control germination by potentiation. We propose that this potentiation is directly mediated by brassinosteroids (BR) because the BR response and synthesis mutants, bri1-5 and det2-1, respectively, share the same GA sensitivity as gpa1 seeds. Furthermore, gpa1 seeds are completely insensitive to brassinolide rescue of germination when the level of GA in seeds is reduced. A lack of BR responsiveness is also apparent in gpa1 roots and hypocotyls suggesting that BR signal transduction is likely coupled by a heterotrimeric G protein at various points in plant development.Seeds integrate many intrinsic signals to control germination (Koornneef et al., 2002). For example, since the original observation by Chrispeels and Varner (1966), it has been repeatedly shown that GA induces germination and that abscisic acid (ABA) antagonizes the GA effect (Koornneef and Van der Veen, 1980;Karssen et al., 1989; Gilroy and Jones, 1994;Ritchie and Gilroy, 1998;Lovegrove and Hooley, 2000). Seed germination of GA synthesis mutants can be rescued by the application of GA and ABA synthesis and insensitive mutants lack the ABA inhibition of GA-induced germination as well as being viviparous (Koornneef et al., 1982(Koornneef et al., , 1984 Finkelstein and Somerville, 1990;Koornneef and Karssen, 1994;Leon-Kloosterziel et al., 1996). Brassinosteroid (BR) probably acts downstream of GA because BR is able to rescue germination of GA-deficient (Steber and McCourt, 2001) and GA response (Steber et al., 1998) mutant seeds. These authors argue that the BR input is likely to reside upstream of ABA's attenuating effect on GA-induced germination because BR synthesis and response mutants have slightly altered ABA sensitivity.The inhibitory effect of high concentrations of sugars on germination may occur via ABA. The evidence supporting this comes from measurements of ABA in Glc-treated seedlings (Arenas-Huertero et al., 2000) and from the observation that ABA synthesis and response mutants are insensitive to Glc (Laby et al., 2000;Rook et al., 2001). Ethylene controls the Glc inhibition of germination (Zhou et al., 1998). Evidence supporting this includes the observations that high concentrations of ethylene antagonize the Glc repression of germination (Ghassemian et al., 2000), the ctr1 (constitutive ethylene response mutant; Gibs...

show abstract

“…Hence, both endogenous GA and ethylene appear to control seed germination by decreasing ABA responsiveness ( Figure 10A). GA and ethylene can replace each other to a certain extent because germination of the ga1 mutant could be induced by exogenous ethylene (Karssen et al, 1989), and conversely, a GA treatment stimulated germination of the etr1-1 mutant (Bleecker et al, 1988). The roles of endogenous GA and ethylene are unlikely to be completely redundant, however, because mutations that impair the action of either of these two hormones lead to tangible alterations in seed germination.…”

mentioning

confidence: 99%

Interactions between Abscisic Acid and Ethylene Signaling Cascades

et al. 2000

View full text Add to dashboard Cite

We screened for mutations that either enhanced or suppressed the abscisic acid (ABA)-resistant seed germination phenotype of the Arabidopsis abi1-1 mutant. Alleles of the constitutive ethylene response mutant ctr1 and ethyleneinsensitive mutant ein2 were recovered as enhancer and suppressor mutations, respectively. Using these and other ethylene response mutants, we showed that the ethylene signaling cascade defined by the ETR1 , CTR1 , and EIN2 genes inhibits ABA signaling in seeds. Furthermore, epistasis analysis between ethylene-and ABA-insensitive mutations indicated that endogenous ethylene promotes seed germination by decreasing sensitivity to endogenous ABA. In marked contrast to the situation in seeds, ein2 and etr1-1 roots were resistant to both ABA and ethylene. Our data indicate that ABA inhibition of root growth requires a functional ethylene signaling cascade, although this inhibition is apparently not mediated by an increase in ethylene biosynthesis. These results are discussed in the context of the other hormonal regulations controlling seed germination and root growth. INTRODUCTIONAbscisic acid (ABA) regulates various aspects of plant growth and development, including seed maturation and dormancy, as well as adaptation to abiotic environmental stresses (Zeevaart and Creelman, 1988; Davies and Jones, 1991). Substantial progress has been made in the characterization of ABA signaling pathways (Busk and Pagès, 1997; Bonetta and McCourt, 1998;Leung and Giraudat, 1998;MacRobbie, 1998). In particular, mutational analyses in Arabidopsis have led to the identification of several genes that control ABA responsiveness. These genetic screens were based primarily on the inhibition of seed germination by applied ABA. The ABA-insensitive ( abi ) mutants abi1 to abi5 are able to germinate in the presence of ABA concentrations that are inhibitory to the wild type (Koornneef et al., 1984;Ooms et al., 1993; Finkelstein, 1994;Nambara et al., 1995). In contrast, germination of the era1 (enhanced response to ABA) to era3 mutant seed is prevented by low concentrations of ABA that ordinarily permit germination of wild-type seed (Cutler et al., 1996). As judged from their impact on seed dormancy, these two sets of mutations also alter the regulation of seed germination by endogenous ABA. Like ABA-deficient mutants (Karssen et al., 1983;Léon-Kloosterziel et al., 1996a), the ABA-insensitive mutants abi1 to abi3 display marked reductions in seed dormancy (Koornneef et al., 1984;Ooms et al., 1993;Nambara et al., 1995). Conversely, the ABA-supersensitive era1 mutation confers enhanced seed dormancy (Cutler et al., 1996).The abi3 , abi4, and abi5 mutants exhibit additional defects in various aspects of seed maturation (Koornneef et al., 1984; Finkelstein and Somerville, 1990;Ooms et al., 1993; Finkelstein, 1994;Parcy et al., 1994;Nambara et al., 1995). The ABI3 and ABI4 genes have been cloned and encode putative transcriptional regulators. ABI3 is orthologous to the maize Viviparous 1 protein (McCarty et al., 1991;Giraudat e...

show abstract

Key Role for Endogenous Gibberellins in the Control of Seed Germination

Cited by 214 publications

References 17 publications

The Effect of α-Amanitin on the Arabidopsis Seed Proteome Highlights the Distinct Roles of Stored and Neosynthesized mRNAs during Germination

The Effect of α-Amanitin on the Arabidopsis Seed Proteome Highlights the Distinct Roles of Stored and Neosynthesized mRNAs during Germination

Role of a Heterotrimeric G Protein in Regulation of Arabidopsis Seed Germination

Interactions between Abscisic Acid and Ethylene Signaling Cascades

Contact Info

Product

Resources

About