Cytokinin
From Purdue Genomics Database Facility
Contents |
Cytokinin metabolisms
M. Kubo and T. Nishiyama
(ku-bo@nibb.ac.jp) (tomoakin@kenroku.kanazawa-u.ac.jp)
Cytokinins (CKs) are N6-substituted adenine derivatives involved in not only cell proliferation and differentiation but also in morphogenesis of tissues and organs in land plants (Kakimoto, 2003). Several key enzymes for CK biosynthesis and metabolisms have been identified (Sakakibara, 2006). CYP735A, a P450 catalyzing next step of IPT reaction were found in only angiosperm lineage. CK oxidases (CKX) catalyze CK degradation by cleavage of its side chain, which play crucial roles in regulating CK levels in plant tissues (Schmülling et al., 2003). We found their potential orthologs in S. moellendorffii and P. patens, but not in the algae. CKX homologs diverged in the each lineage in parallel.
Cytokinin signalling
M. Kubo, T. Aoyama, and T. Nishiyama
(ku-bo@nibb.ac.jp) (tomoakin@kenroku.kanazawa-u.ac.jp)
Cytokinin (CK)signal transduction is mediated by a two-component system with histidine kinases as CK receptors and response regulators (Kakimoto, 2003). We found putative orthologues of the A. thaliana CK receptors in S. moellendorffii and P. patens. The CK receptor land plant orthologues expanded in the angiosperms, S. moellendorffii, and P. patens lineages in parallel. Phosphotransmitters (AHPs), which mediate phosphorylation signals from the CK receptors to response regulators, were found in each land plant lineage and were expanded in each lineage. Response regulators are classified as type-A (ARR-A) or type-B (ARR-B). The ARR-A genes were divided into two groups: ARR22 and other. We found land plant orthologues in each lineage for both groups, indicating these groups separated before the divergence of P. patens from other land plants. The ARR-A homologues expanded in each land plant lineage, which suggests the functional divergence of ARR-A amongst the lineages. All land plants had ARR-B genes, although they diverged more extensively in the angiosperm lineage than in other lineages.
References
Kakimoto, T. (2003). Biosynthesis of cytokinins. Journal Plant Research 116, 233-239.
Kakimoto, T. (2003). Perception and signal transduction of cytokinins. Annu. Rev. Plant Biol. 54, 605-627.
Sakakibara, H. (2006). Cytokinins: Activity, biosynthesis, and translocation. Annual Review of Plant Biology 57, 431-449.
Schmülling, T., Werner, T., Riefler, M., Krupková, E., and Bartrina y Manns, I. (2003). Structure and function of cytokinin oxidase/dehydrogenase genes of maize, rice, Arabidopsis and other species. J. Plant Res. 116, 241-252.
Table of gene numbers
| Gene functions | Gene | Gene used as a query | The number of putative orthologs | |||
|---|---|---|---|---|---|---|
| Arabidopsis thaliana | Oryza sativa | Selaginalla moellendorffii | Physcomitrella patens | |||
| Cytokinin metabolisms | CYP735A | CYP735A1 | 2 | 2 | 0 | 0 |
| Cytokinin metabolisms | CKX | CKX7 | 7 | 9 | 3 (5) | 6 |
| Cytokinin signalling | AHK2, 3, and CRE1/WOL/AHK4 | CRE1 | 3 | 5 | 2 (3) | 3 |
| Cytokinin signalling | AHP1 to 6 | AHP2 | 7 | 4 | 2 (4) | 3 |
| Cytokinin signalling | ARR3 to 9, 15 to 17 | ARR5 | 11 | 15 | 2 (4) | 7 |
| Cytokinin signalling | ARR22 | ARR22 | 2 | 1 | 2 (3) | 3 |
| Cytokinin signalling | ARR1, 2, 10 to 14, 18 to 21, and 23 | ARR1 | 12 | 9 | 5 (9) | 5 |
Table of gene models in the assembly
| protein id | gene name | alternate model | other name | by whom |
| CKX related genes | ||||
|---|---|---|---|---|
| 98722 | CKX1-1 | |||
| 127173 | CKX1-2 | |||
| 174721 | CKX2-1 | |||
| 106833 | CKX2-2 | |||
| CRE1 related genes | ||||
| 152221 | CRE1-1 | HK2 | heyl | |
| 158365 | CRE1-2 | |||
| 231095 | CRE2-1 | HK1 | heyl | |
| 430773 | CRE2-2 | |||
| AHP2 related genes | ||||
| 267058 | HP1-1 | HP1 | heyl | |
| 152299 | HP1-2 | |||
| 84165 | HP2-1 | HP2 | heyl | |
| 179923 | HP2-2 | |||
| ARR5 related genes | ||||
| 437754 | RR7-1 | RR7 | heyl | |
| 444661 | RR7-2 | |||
| 445841 | RR6-1 | RR6 | heyl | |
| 97144 | RR6-2 | |||
| ARR1 related genes | ||||
| 442188 | RR1-1 | RR1 | heyl | |
| 150746 | RR1-2 | |||
| 450181 | RR2-1 | RR2 | heyl | |
| 173793 | RR2-2 | |||
| 418787 | RR3-1 | RR3 | heyl | |
| 187683 | RR3-2 | |||
| 444702 | RR4-1 | RR4 | heyl | |
| 447635 | RR4-2 | |||
| 440049 | RR5-1 | RR5 | heyl | |
| 115021 | RR5-2 | |||
| ARR22 related genes | ||||
| 451426 | HK5-1 | |||
| 449209 | HK5-2 | |||
| 451436 | HK6-1 | PRR6 | heyl | |
| 451432 | HK6-2 | |||
| genes checked for comparison | ||||
| 451444 | SHPK6-1 | 449750 | SHPK6 | Jody Banks |
| 451443 | SHPK6-2 | 101918 | RR8 | heyl |
