Comparative Expression and Phylogenetic Analysis of Maize Cytokinin Dehydrogenase/Oxidase (CKX) Gene Family

Gu, Rong; Fu, Junjie; Guo, Song; Duan, Fengying; Wang, Zhangkui; Mi, Guohua; Yuan, Lixing

doi:10.1007/s00344-010-9155-y

Cited by 52 publications

(54 citation statements)

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“…The spatial and temporal distributions of bioactive cytokinin level are also strictly controlled for plant development events. There exist 11 genes encoding for CKX in the rice genome, with two sets of segmental duplication genes (OsCKX4/ OsCKX9 and OsCKX3/OsCKX8) and a pair of tandem duplication genes (OsCKX6/OsCKX7; Ashikari et al, 2005;Gu et al, 2010). Although some characterizations of OsCKX genes have been reported recently Tsai et al, 2012), only OsCKX2 has been characterized in detail to date.…”

Section: Discussionmentioning

confidence: 99%

“…A BLAST search indicated that OsCKX4 contains a FAD-binding domain located at its N terminus and a cytokinin-binding site located at its C terminus. Phylogenetic analysis shows that OsCKX4 is more closely related to Arabidopsis CKX proteins, indicating that separation of the present CKX genes occurred before the separation of monocot and dicot plants Gu et al, 2010).…”

Section: Phenotypes Of Ren1-d Are Caused By Activation Taggingmentioning

confidence: 99%

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CYTOKININ OXIDASE/DEHYDROGENASE4 Integrates Cytokinin and Auxin Signaling to Control Rice Crown Root Formation

et al. 2014

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Crown roots constitute the majority of the rice (Oryza sativa) root system and play an important role in rice growth and development. However, the molecular mechanism of crown root formation in rice is not well understood. Here, we characterized a rice dominant mutant, root enhancer1 (ren1-D), which was observed to exhibit a more robust root system, increased crown root number, and reduced plant height. Molecular and genetic analyses revealed that these phenotypes are caused by the activation of a cytokinin oxidase/dehydrogenase (CKX) family gene, OsCKX4. Subcellular localization demonstrated that OsCKX4 is a cytosolic isoform of CKX. OsCKX4 is predominantly expressed in leaf blades and roots. It is the dominant CKX, preferentially expressed in the shoot base where crown root primordia are produced, underlining its role in root initiation. OsCKX4 is induced by exogenous auxin and cytokinin in the roots. Furthermore, one-hybrid assays revealed that OsCKX4 is a direct binding target of both the auxin response factor OsARF25 and the cytokinin response regulators OsRR2 and OsRR3. Overexpression and RNA interference of OsCKX4 confirmed that OsCKX4 plays a positive role in crown root formation. Moreover, expression analysis revealed a significant alteration in the expression of auxin-related genes in the ren1-D mutants, indicating that the OsCKX4 mediates crown root development by integrating the interaction between cytokinin and auxin. Transgenic plants harboring OsCKX4 under the control of the root-specific promoter RCc3 displayed enhanced root development without affecting their shoot parts, suggesting that this strategy could be a powerful tool in rice root engineering.

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Section: Discussionmentioning

confidence: 99%

Section: Phenotypes Of Ren1-d Are Caused By Activation Taggingmentioning

confidence: 99%

CYTOKININ OXIDASE/DEHYDROGENASE4 Integrates Cytokinin and Auxin Signaling to Control Rice Crown Root Formation

et al. 2014

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“…2b). Both the IPT and CKX genes coexist in the moss Physcomitrella patens, which points to an important evolutionary event generating fine-tuning control of CK homeostasis via biosynthesis and degradation processes (Gu et al 2010). tRNA-IPTs are evolutionally conserved throughout the whole phylogenetic tree, whereas adenylate IPTs that are capable of de novo CK synthesis occurred later during the evolution of seed plants (Fig.…”

Section: Evolution Of Ck Machinery In Plantsmentioning

confidence: 97%

“…The algal biosynthetic pathway has not been confirmed yet, no CK-metabolic genes have been identified so far in algal genomes (Gu et al 2010), and only Type B response regulators (RRs) -but not the cytokinin receptor -have been found in the green unicellular microalgae Chlamydomonas reinhardtii (Pils and Heyl 2009). Two scenarios were suggested for the evolution of CK signalling in algae by Pils and Heyl (2009): (1) algae that were not confronted with the new stress conditions faced by the land conquesting plants and did not need more elaborate developmental programmes requiring a new or more complex regulation of CKs could have lost the CHASE domain His kinase fixed in the last common ancestor of amoebae and algae over time, or (2) CHASE domain His kinase exists in the charaphytes that are ancestral to land plants but the fact that their genome sequences have not been mapped yet has prevented the identification of CK receptors in these algae lineages.…”

Section: Evolution Of Ck Machinery In Plantsmentioning

confidence: 99%

“…In all genomes sequenced so far, one cytosolic CKX is always conserved (Frébort et al 2011). However, in the basal land plants Physcomitrella and Selaginella, other putative CKXs have been identified (Gu et al 2010;Frébort et al 2011). This already implies the drastic expansion of CKX genes into multigene families with a varying number of members with the diverse functions, expression patterns and (sub)cellular localisations that are typical of higher plants (Gu et al 2010).…”

Section: Evolution Of Ck Machinery In Plantsmentioning

confidence: 99%

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Cytokinins - recent news and views of evolutionally old molecules

Spíchal¹

2012

Functional Plant Biol.

159

169

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Cytokinins (CKs) are evolutionally old and highly conserved low-mass molecules that have been identified in almost all known organisms. In plants, they evolved into an important group of plant hormones controlling many physiological and developmental processes throughout the whole lifespan of the plant. CKs and their functions are, however, not unique to plants. In this review, the strategies and mechanisms of plants – and phylogenetically distinct plant-interacting organisms such as bacteria, fungi, nematodes and insects employing CKs or regulation of CK status in plants – are described and put into their evolutionary context. The major breakthroughs made in the last decade in the fields of CK biosynthesis, degradation and signalling are also summarised.

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The soybean (Glycine max L.) cytokinin oxidase/dehydrogenase multigene family; Identification of natural variations for altered cytokinin content and seed yield

et al. 2021

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Cytokinins (CKs) play a fundamental role in regulating dynamics of organ source/sink relationships during plant development, including flowering and seed formation stages. As a result, CKs are key drivers of seed yield. The cytokinin oxidase/dehydrogenase (CKX) is one of the critical enzymes responsible for regulating plant CK levels by causing their irreversible degradation. Variation of CKX activity is significantly correlated with seed yield in many crop species while in soybean (Glycine max L.), the possible associations between CKX gene family members (GFMs) and yield parameters have not yet been assessed. In this study, 17 GmCKX GFMs were identified, and natural variations among GmCKX genes were probed among soybean cultivars with varying yield characteristics. The key CKX genes responsible for regulating CK content during seed filling stages of reproductive development were highlighted using comparative phylogenetics, gene expression analysis and CK metabolite profiling. Five of the seventeen identified GmCKX GFMs, showed natural variations in the form of single nucleotide polymorphisms (SNPs). The gene GmCKX7‐1, with high expression during critical seed filling stages, was found to have a non‐synonymous mutation (H105Q), on one of the active site residues, Histidine 105, previously reported to be essential for co‐factor binding to maintain structural integrity of the enzyme. Soybean lines with this mutation had higher CK content and desired yield characteristics. The potential for marker‐assisted selection based on the identified natural variation within GmCKX7‐1, is discussed in the context of hormonal control that can result in higher soybean yield.

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Comparative Expression and Phylogenetic Analysis of Maize Cytokinin Dehydrogenase/Oxidase (CKX) Gene Family

Cited by 52 publications

References 40 publications

CYTOKININ OXIDASE/DEHYDROGENASE4 Integrates Cytokinin and Auxin Signaling to Control Rice Crown Root Formation

CYTOKININ OXIDASE/DEHYDROGENASE4 Integrates Cytokinin and Auxin Signaling to Control Rice Crown Root Formation

Cytokinins - recent news and views of evolutionally old molecules

The soybean (Glycine max L.) cytokinin oxidase/dehydrogenase multigene family; Identification of natural variations for altered cytokinin content and seed yield

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