Rice dwarf mutant
            <i>d1</i>
            , which is defective in the α subunit of the heterotrimeric G protein, affects gibberellin signal transduction

Ueguchi-Tanaka, Miyako; Fujisawa, Yukiko; Kobayashi, Masatomo; Ashikari, Motoyuki; Iwasaki, Yukimoto; Kitano, Hidemi; Matsuoka, Makoto

doi:10.1073/pnas.97.21.11638

Cited by 351 publications

(306 citation statements)

References 34 publications

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“…Rice d1 mutant also has been shown to have less sensitivity to GA as it is defective in GA 3 -induced α-amylase activity in the aleurone layer [9]. Moreover, RNA blot analysis has shown three GA-inducible genes, OsMYB, Ca 2+ -ATPase and Ramy1, with a weaker response to GA in d1 mutant than in wild-type plant [9].…”

Section: Discussionmentioning

confidence: 99%

“…In addition, RNA blot analysis showed that GA-inducible genes, OsMYB, Ca 2+ -ATPase and Ramy1, had a weaker response to GA in the d1 mutant than that in control plants [9]. Epistatic analysis showed that slr (slender rice), caused by mutation in a crucial regulator in GA signaling, is epistatic to d1 [9]. Undoubtedly, this evidence revealed that GA signaling is affected in the d1 mutant.…”

Section: Introductionmentioning

confidence: 90%

“…Investigation of dose response to gibberellic acid (GA 3 ) revealed that the d1 mutant showed defective induction of α-amylase activity in the aleurone layer as compared to wild-type plants. In addition, RNA blot analysis showed that GA-inducible genes, OsMYB, Ca 2+ -ATPase and Ramy1, had a weaker response to GA in the d1 mutant than that in control plants [9]. Epistatic analysis showed that slr (slender rice), caused by mutation in a crucial regulator in GA signaling, is epistatic to d1 [9].…”

Section: Introductionmentioning

confidence: 99%

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Heterotrimeric G protein α subunit is involved in rice brassinosteroid response

Wang

et al. 2006

Cell Res

112

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Heterotrimeric G proteins are known to function as messengers in numerous signal transduction pathways. The null mutation of RGA (rice heterotrimeric G protein α subunit), which encodes the α subunit of heterotrimeric G protein in rice, causes severe dwarfism and reduced responsiveness to gibberellic acid in rice. However, less is known about heterotrimeric G protein in brassinosteroid (BR) signaling, one of the well-understood phytohormone pathways. In the present study, we used root elongation inhibition assay, lamina inclination assay and coleoptile elongation analysis to demonstrated reduced sensitivity of d1 mutant plants (caused by the null mutation of RGA) to 24-epibrassinolide (24-epiBL), which belongs to brassinosteroids and plays a wide variety of roles in plant growth and development. Moreover, RGA transcript level was decreased in 24-epiBL-treated seedlings in a dose-dependent manner. Our results show that RGA is involved in rice brassinosteroid response, which may be beneficial to elucidate the molecular mechanisms of G protein signaling and provide a novel perspective to understand BR signaling in higher plants.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Heterotrimeric G protein α subunit is involved in rice brassinosteroid response

Wang

et al. 2006

Cell Res

112

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“…The reduction in cell number in G protein mutants is compensated in many cases by cell elongation to achieve nearly normal morphology. Nonetheless, G protein mutants have altered sensitivities to several hormones (Ashikari et al, 1999;Fujisawa et al, 1999;Ueguchi-Tanaka et al, 2000;Ullah et al, 2001Ullah et al, , 2002Ullah et al, , 2003Wang et al, 2001). The reduced perception of some hormones and the complete loss in others in the G protein mutants must impact cellular responsiveness to many signals.…”

Section: Resultsmentioning

confidence: 99%

A Reevaluation of the Role of the Heterotrimeric G Protein in Coupling Light Responses in Arabidopsis

2003

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Previous studies implicated the involvement of a heterotrimeric G protein in red (R) and far-red (FR) light signal transduction, but these studies utilized pharmacological or gain-of-function approaches and, therefore, are indirect tests. Here, we reexamine the role of the single canonical heterotrimeric G protein in R and FR control of hypocotyl growth using a loss-of-function approach. Single-and double-null mutants for the GPA1, AGB1 genes encoding the alpha and beta subunit of the heterotrimeric G protein, respectively, have wild-type sensitivity to R and FR. Ectopic overexpression of wild type and a constitutive active form of the alpha subunit and of the wild-type beta subunit had no effect that can be unequivocally attributed to altered R and FR responsiveness. These results preclude a direct role for the heterotrimeric G complex in R and FR transduction in Arabidopsis leading to growth control in the hypocotyl.The classic example of the molecular coupling of signals by a heterotrimeric G protein to a downstream effector is vision in animals where the alpha subunit of the cognate heterotrimeric complex, transducin, couples the activated heptahelical membrane receptor rhodopsin to its cGMP phosphodiesterase effector in rod photoreceptor cells (Baylor, 1996). Plant cells are also light sensitive, especially in the red (R)/far-red (FR) light spectral region due to its highly light-sensitive family of photoreceptors called phytochrome. Therefore, an obvious question has been whether phytochrome light perception is similarly coupled by a heterotrimeric G protein to an unidentified downstream effector. Two influential papers of the early 1990s suggested that it is (Bowler et al., 1994;Neuhaus et al., 1993). In these elegant studies, some phenotypes of a tomato (Lycopersicon esculentum) phytochrome mutant could be rescued to wild type by pertussis and cholera toxins, agents that stabilize the activated form of the G protein subunit by different means. Furthermore, microinjection of cGMP induced some phytochrome-mediated events in the dark. These observations led these authors to conclude that a heterotrimeric G protein was positioned downstream of phytochrome in the light signal transduction pathway and upstream of a cGMPmediated step, in analogy to light perception in animals. Several other labs used pharmacological approaches in different systems and came to the same conclusion. Electroporation of GDP␤S blocked R-induced protoplast swelling, whereas GTP␥S induced swelling in darkness (Bosson et al., 1990). Cholera toxin was shown to increase the steady-state mRNA levels of the light-regulated gene, CAB (Romero and Lam, 1993).More recently, Okamota and colleagues took a gain-of-function approach to test this hypothesis and concluded with all previous authors that a heterotrimeric G protein is involved in phytochromemediated signal transduction (Okamota et al., 2001). The authors reported that Arabidopsis ectopically overexpressing the alpha subunit of the heterotrimeric G protein, regardless of the G␣ activatio...

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“…GAs consist of a large family of tetracyclic diterpenoids and are associated with a number of plant growth and developmental processes such as seed germination, stem elongation, flowering and fruit development (Reid 1993, Hooley 1994, Ross et al 1997. To date, we have screened and characterized several rice GArelated mutants and isolated the genes involved in GA biosynthesis and signal transduction in the rice plant (Ashikari et al 1999, Ueguchi-Tanaka et al 2000, Ikeda et al 2001, Itoh et al 2001. Through these studies, we recognized that the plant morphology of the sd1 mutants was similar to that of GA-deficient mutants with a weak phenotype.…”

Section: Physiological Characterization Of Sd1mentioning

confidence: 99%

Loss-of-function of a Rice Gibberellin Biosynthetic Gene, GA20 oxidase (GA20ox-2), Led to the Rice 'Green Revolution'.

et al. 2002

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A rice semi-dwarf variety, IR8, known as "miracle rice" enabled dramatic increases rice production and its widespread adoption averted predicted food shortages in Asia during the 1960s to 1990s. This remarkable achievement was referred to as "green revolution". The short stature of IR8 was derived from the semi-dwarf gene, sd1, and the sd1 gene contributed significantly to the rice "green revolution". In this paper, we described the physiological, molecular genetic and biochemical characterization of the sd1 gene. The sd1 mutant contained lower gibberellin (GA) levels than wild-type plants but responded sensitively to exogenous GA. Cloning and sequence analyses revealed that the SD1 gene encoded a GA biosynthetic enzyme, GA20 oxidase. In all of the sd1 mutants tested, nucleotide deletions or substitutions were observed in the GA20 oxidase gene (GA20ox-2), which induced an internal stop codon or single amino acid substitutions, respectively. The sd1 plants, which the wild-type GA20ox-2 gene was introduced showed the normal height. A recombinant GA20ox-2 protein produced from the cDNA clone in E. coli catalyzed the conversion of GA 53 to GA 20 . These results confirmed that SD1 encodes an active GA20 oxidase. The expression of GA20ox-2 was down-regulated by GA in a similar manner to that of some GA20oxs in other plants. The rice genome carried at least two GA 20-oxidase genes (GA20ox-1 and GA20ox-2) and SD1 corresponded to GA20ox-2, which is highly expressed in the leaves and flowers, whereas GA20ox-1 is preferentially expressed in the flowers. The reduced plant height associated with the sd1 alleles was due to the low amount of active GA in leaves, which was caused by a mutation of the GA20ox-2 gene. On the basis of these results, we discussed the importance of GA in the regulation of plant height in crop breeding.

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Rice dwarf mutant d1 , which is defective in the α subunit of the heterotrimeric G protein, affects gibberellin signal transduction

Cited by 351 publications

References 34 publications

Heterotrimeric G protein α subunit is involved in rice brassinosteroid response

Heterotrimeric G protein α subunit is involved in rice brassinosteroid response

A Reevaluation of the Role of the Heterotrimeric G Protein in Coupling Light Responses in Arabidopsis

Loss-of-function of a Rice Gibberellin Biosynthetic Gene, GA20 oxidase (GA20ox-2), Led to the Rice 'Green Revolution'.

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