Identification and characterization of cytokinin-signalling gene families in rice

Ito, Yukihiro; Kurata, Nori

doi:10.1016/j.gene.2006.06.020

Cited by 114 publications

(118 citation statements)

References 29 publications

(43 reference statements)

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“…Furthermore, N assimilation and cytokinin-related genes are also quite conserved in higher plants. This includes the His kinase cytokinin receptors as well as downstream phosphotransfer proteins, type A and type B ARRs involved in cytokinin signal transduction (Ito and Kurata, 2006). It is unclear whether Cga1 expression increases as a direct result of N application or indirectly increased through N-induced cytokinin production.…”

Section: Conserved Regulation Of Cga1mentioning

confidence: 99%

Rice Cytokinin GATA Transcription Factor1 Regulates Chloroplast Development and Plant Architecture

et al. 2013

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Chloroplast biogenesis has been well documented in higher plants, yet the complex methods used to regulate chloroplast activity under fluctuating environmental conditions are not well understood. In rice (Oryza sativa), the CYTOKININ-RESPONSIVE GATA TRANSCRIPTION FACTOR1 (Cga1) shows increased expression following light, nitrogen, and cytokinin treatments, while darkness and gibberellin reduce expression. Strong overexpression of Cga1 produces dark green, semidwarf plants with reduced tillering, whereas RNA interference knockdown results in reduced chlorophyll and increased tillering. Coexpression, microarray, and real-time expression analyses demonstrate a correlation between Cga1 expression and the expression of important nucleus-encoded, chloroplast-localized genes. Constitutive Cga1 overexpression increases both chloroplast biogenesis and starch production but also results in delayed senescence and reduced grain filling. Growing the transgenic lines under different nitrogen regimes indicates potential agricultural applications for Cga1, including manipulation of biomass, chlorophyll/ chloroplast content, and harvest index. These results indicate a conserved mechanism by which Cga1 regulates chloroplast development in higher plants.

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Section: Conserved Regulation Of Cga1mentioning

confidence: 99%

Rice Cytokinin GATA Transcription Factor1 Regulates Chloroplast Development and Plant Architecture

et al. 2013

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“…The Arabidopsis genome harbors 3 loci for the cytokinin receptors, CRE1/WOL, AHK2, and AHK3, all of which belong to the superfamily of 2-component regulators (12,24). The CRE cytokinin receptor gene family has been shown to be conserved between the non-woody plant species Arabidopsis, rice, and maize (25,26).…”

Section: The Cre Cytokinin Receptor Gene Family Is Conserved Betweenmentioning

confidence: 99%

Cytokinin signaling regulates cambial development in poplar

Nieminen

Immanen²,

Laxell³

et al. 2008

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

245

204

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Although a substantial proportion of plant biomass originates from the activity of vascular cambium, the molecular basis of radial plant growth is still largely unknown. To address whether cytokinins are required for cambial activity, we studied cytokinin signaling across the cambial zones of 2 tree species, poplar (Populus trichocarpa) and birch (Betula pendula). We observed an expression peak for genes encoding cytokinin receptors in the dividing cambial cells. We reduced cytokinin levels endogenously by engineering transgenic poplar trees (P. tremula ؋ tremuloides) to express a cytokinin catabolic gene, Arabidopsis CYTOKININ OXI-DASE 2, under the promoter of a birch CYTOKININ RECEPTOR 1 gene. Transgenic trees showed reduced concentration of a biologically active cytokinin, correlating with impaired cytokinin responsiveness. In these trees, both apical and radial growth was compromised. However, radial growth was more affected, as illustrated by a thinner stem diameter than in WT at same height. To dissect radial from apical growth inhibition, we performed a reciprocal grafting experiment. WT scion outgrew the diameter of transgenic stock, implicating cytokinin activity as a direct determinant of radial growth. The reduced radial growth correlated with a reduced number of cambial cell layers. Moreover, expression of a cytokinin primary response gene was dramatically reduced in the thin-stemmed transgenic trees. Thus, a reduced level of cytokinin signaling is the primary basis for the impaired cambial growth observed. Together, our results show that cytokinins are major hormonal regulators required for cambial development.cambial activity ͉ cambium ͉ secondary development ͉ Populus ͉ CYTOKININ OXIDASE

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“…It was reported that the expression of OsNSHB2, which has one AGATT motif in its promoter, is regulated by cytokinin (Ross et al, 2004). In the cytokinin signaling pathway of rice, cytokinin signals are received by His kinases and then transferred to B-type RRs by His phosphotransfer proteins (Ito and Kurata, 2006). In the following, B-type RR possibly down-regulates OsMT2b expression.…”

Section: There Is Correlation Between Osmt2b Gene Expression and Cytomentioning

confidence: 99%

“…In rice, 23 A-type and six B-type response regulator (RR) genes had been identified (Jain et al, 2006;Ito and Kurata, 2006). Among them, the OsRR6-overexpression transformants had an increased content of TZ-type cytokinins and showed dwarf phenotypes with poorly developed root systems (Hirose et al, 2007).…”

mentioning

confidence: 99%

Characteristic and Expression Analysis of a Metallothionein Gene, OsMT2b, Down-Regulated by Cytokinin Suggests Functions in Root Development and Seed Embryo Germination of Rice

et al. 2008

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Metallothioneins (MTs) are low molecular mass and cysteine-rich metal-binding proteins known to be mainly involved in maintaining metal homeostasis and stress responses. But, their functions in higher plant development are scarcely studied. Here, we characterized rice (Oryza sativa) METALLOTHIONEIN2b (OsMT2b) molecularly and found that its expression was down-regulated by cytokinins. OsMT2b was preferentially expressed in rice immature panicles, scutellum of germinating embryos, and primordium of lateral roots. In contrast with wild-type plants, OsMT2b-RNA interference (RNAi) transgenic plants had serious handicap in plant growth and root formation, whereas OsMT2b-overexpressing transformants were dwarfed and presented more adventitious roots and big lateral roots. The increased cytokinin levels in RNAi plants and decreased cytokinin levels in overexpressing plants were confirmed by high-performance liquid chromatography quantitative analysis in the roots of wild-type and transgenic plants. In RNAi plants, localization of isopentenyladenosine, a kind of endogenous cytokinin, in roots and germinating embryos expanded to the whole tissues, whereas in overexpressing plants, the isopentenyladenosine signals were very faint in the vascular tissues of roots and scutellum cells of germinating embryos. In vitro culture of embryos could largely resume the reduced germination frequency in RNAi plants but had no obvious change in overexpressing plants. Taken together, these results indicate a possible feedback regulation mechanism of OsMT2b to the level of endogenous cytokinins that is involved in root development and seed embryo germination of rice.

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Identification and characterization of cytokinin-signalling gene families in rice

Cited by 114 publications

References 29 publications

Rice Cytokinin GATA Transcription Factor1 Regulates Chloroplast Development and Plant Architecture

Rice Cytokinin GATA Transcription Factor1 Regulates Chloroplast Development and Plant Architecture

Cytokinin signaling regulates cambial development in poplar

Characteristic and Expression Analysis of a Metallothionein Gene, OsMT2b, Down-Regulated by Cytokinin Suggests Functions in Root Development and Seed Embryo Germination of Rice

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