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D10transcription might be a critical step in the regulation of the branching inhibitor pathway.

Annotated Information


D10,carotenoid cleavage dioxygenase 8(OsCCD8)controls lateral bud outgrowth of rice, and then ultimate control of rice tillers. OsCCD8 is an important enzyme of biosynthesis Strigolactones process.It´s involved in the biosynthesis of Strigolactones / Strigolactones derivative SL.And D10 may play an important role in auxin regulation of SL.D10 may plays an important role in regulate Strigolactones and its derivatives by auxin , but may reduce the transport ability of auxin and promote the synthesis of cytokinin by reducing the auxin levels at the same time.


Localization ofD10expression (from reference [1]).
Analysis of feedback regulation of D10 and other branching genes (from reference [1]).

D10 is a carotenoid cleavage dioxygenase, mainly expressed in vascular cells of various organs, and induced by exogenous auxin.D10 expression predominantly occurs in vascular cells in most organs. Real-time polymerase chain reaction analysis revealed that accumulation of D10 mRNA is induced by exogenous auxin. In addition, the expression of D10 up-regulated in 6 mutated branches,including d3,d10,d14,d17,d27,htdi.But MAX2 and MAX3 rice homologous gene D3 and HTD1 have no expression change in these mutants. These finding may indicate that D10's transcription may be key factor of regulating branches inhibition pathway. [1]

Tissue specificity of the expression of D10 and other rice branching genes was examined by reverse transcription polymerase chain reaction (RT-PCR) analysis (Figure 1a). Low levels of D10mRNA were detected in all tissues examined, except for the root tip. Expression in lateral buds and shoot apices was slightly higher than in panicles, leaves and roots. In contrast,D10likewas expressed predominantly in the panicle. As previously reported, D3andHTD1were expressed in all tissues [2]. Tissue-specific distribution of D10 mRNA was further examined using the D10 promoter GUS(D10:GUS) chimeric gene (Figure 1b–h). Despite differences in the overall intensity of GUS activity, all nine transgenic lines showed a common pattern of GUS distribution. As shown in Figure 1b, GUS staining was detected in vascular cells in roots, nodes, internodes and the inflorescence. GUS expression was hardly observed in leaves . A relatively high level of GUS expression was observed in roots (Figure 1c,d). Consistent with the results obtained from RTPCR analysis, root tips did not show GUS activity. Analysis with a longitudinal section of the root indicated that the GUS activity was localized in the parenchyma cells in the root stele (Figure 1e,f). In the stem, GUS activity was localized in xylem parenchyma cells (Figure 1g,h). As shown in Figure 2, levels of D10transcripts were substantially increased in all five dmutants, whereas no such effect was observed infc1. Interestingly,D10like,D3andHTD1expression was unaltered indandfc1mutants, indicating that the level ofD10mRNA accumulation might be a critical step in the regulation of the synthesis of the branching inhibitor.

Primer Forward primer Reverse primer


D10 orthologs have been isolated from four species: rice, pea, Arabidopsis and petunia. Feedback upregulation has been observed in three of them: pea RMS1 [3], petunia DAD1 [4] and rice D10. Although details of molecular mechanisms underlying the feedback control of D10, RMS1 and DAD1 remain to be unraveled, and although the extent of the upregulation varies widely between the three genes, the conservation of the feedback effect indicates that the adjustment of the branching inhibitor level by D10 plays a significant role in the control of shoot branching. D10 is a rice ortholog of MAX4/RMS1/DAD1 that encodes a carotenoid cleavage dioxygenase 8 and is supposed to be involved in the synthesis of an unidentified inhibitor of shoot branching.encoding a member of the 9-cis epoxycarotenoid dioxygenase family ,is responsible for the synthesis of a novel carotenoid-derived signal molecule that controls shoot branching in rice.

Knowledge Extension

Although molecular cloning has not yet been performed, the three genes D14,D17 and D27 are likely to function in the same pathway asD3andD10, because a feedback regulation of D10expression was observed in d14, d17 and d27 mutants as ind3, d10andhtd1. So far, mutants of four MAX loci in Arabidopsis, four peaRMSgenes (RMS1,RMS3, RMS4andRMS5) and one petunia gene,DAD1, which show similar enhanced-branching phenotypes, have been characterized at the molecular level.Although the rice mutant corresponding to max1has not yet been identified, the mapped positions ofD14,D17andD27suggest that none of them corresponds to MAX1.

A proposed model of Strigolactone(SL) signalling patyway [5]).

Strigolactones (SLs) are a group of newly identified plant hormones that control plant shoot branching[5]. SL signaling requires the hormone-dependent interaction of DWARF14 (D14) which is regulated by the interaction of OsMADS57 with OsTB1[6]. In this study[5], they have identified theD53gene that encodes a substrate of the SCF(D3) ubiquitination complex, and revealed that D53 functions as a repressor ofSL signalling. These results allow to establish a model of SL signalling that is centred around a D14–D3–D53 signalling axis . In the presence of SLs, perception of SL by D14 and the SCF(D3) complex leads to ubiquitination of D53 and its subsequent degradation by the ubiquitin proteasome system, which in turn releases the repression of downstream target genes . In the d53 plant, the mutated D53 protein is resistant to ubiquitination and degradation, leading to the accumulation of d53, which blocks SL signalling and results in dwarf and high tillering phenotypes. The signalling paradigm of SLs is still emerging as SLs are a relatively new class of plant hormone for which many knowledge gaps still exist. Identification of D53 as a repressor of SL signalling adds a critical piece of information that helps to paint the whole picture of the SL signalling pathways. Moreover, the work has also provided an important paradigm for understanding signalling pathways of other plant hormones, for example, karrikins, a class of plant growth regulators found in the smoke of burning plants. Karrikin signalling involves MAX2 and KAI2, a D14-like α / β-hydrolase. It is probable that a similar protein to D53 could serve as the repressor of karrikin signalling. Indeed, multiple D53-like proteins are found in rice and inArabidopsis. We propose that these proteins could serve as repressors of signalling by karrikin and other plant hormones, in a similar way to D53 in SL signalling.[5]

Labs working on this gene

  • The State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences
  • College of Biological Sciences and Biotechnology, Beijing Forestry University
  • Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo
  • RIKEN Plant Science Center, Japan
  • Research Institute for Bioresources, Okayama University, Kurashiki, Okayama 710-0046, Japan

Structured Information

Structured Information

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