• MeSH
• Chorionic Gonadotropin MeSH
• Gibberellins MeSH
• Mice MeSH
• Pregnancy MeSH
• Neoplasm Transplantation MeSH
• Check Tag
• Mice MeSH
• Pregnancy MeSH

Global inspection of plant genomes identifies genes maintained in low copies across taxa and under strong purifying selection, which are likely to have essential functions. Based on this rationale, we investigated the function of the low-duplicated CYP715 cytochrome P450 gene family that appeared early in seed plants and evolved under strong negative selection. Arabidopsis CYP715A1 showed a restricted tissue-specific expression in the tapetum of flower buds and in the anther filaments upon anthesis. cyp715a1 insertion lines showed a strong defect in petal development, and transient alteration of pollen intine deposition. Comparative expression analysis revealed the downregulated expression of genes involved in pollen development, cell wall biogenesis, hormone homeostasis, and floral sesquiterpene biosynthesis, especially TPS21 and several key genes regulating floral development such as MYB21, MYB24, and MYC2. Accordingly, floral sesquiterpene emission was suppressed in the cyp715a1 mutants. Flower hormone profiling, in addition, indicated a modification of gibberellin homeostasis and a strong disturbance of the turnover of jasmonic acid derivatives. Petal growth was partially restored by the active gibberellin GA3 or the functional analog of jasmonoyl-isoleucine, coronatine. CYP715 appears to function as a key regulator of flower maturation, synchronizing petal expansion and volatile emission. It is thus expected to be an important determinant of flower-insect interaction.

• MeSH
• Arabidopsis classification   enzymology   genetics   growth & development   MeSH
• Phylogeny MeSH
• Conserved Sequence MeSH
• Flowers classification   enzymology   genetics   growth & development   MeSH
• Arabidopsis Proteins chemistry   genetics   metabolism   MeSH
• Gene Expression Regulation, Plant MeSH
• Plants classification   enzymology   genetics   MeSH
• Seeds classification   enzymology   genetics   growth & development   MeSH
• Cytochrome P-450 Enzyme System chemistry   genetics   metabolism   MeSH
• Gene Expression Regulation, Developmental MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Cytokinin (CK) signalling is known to play key roles in the regulation of plant growth and development, crop yields, and tolerance to both abiotic stress and pathogen defences, but the mechanisms involved are poorly characterized in dicotyledonous crops. Here the identification and functional characterization of sensor histidine kinases homologous to Arabidopsis CK receptors AHK2 and AHK3 in winter oilseed rape are presented. Five CHASE-containing His kinases were identified in Brassica napus var. Tapidor (BnCHK1-BnCHK5) by heterologous hybridization of its genomic library with gene-specific probes from Arabidopsis. The identified bacterial artificial chromosome (BAC) clones were fingerprinted and representative clones in five distinct groups were sequenced. Using a bioinformatic approach and cDNA cloning, the precise gene and putative protein domain structures were determined. Based on phylogenetic analysis, four AHK2 (BnCHK1-BnCHK4) homologues and one AHK3 (BnCHK5) homologue were defined. It is further suggested that BnCHK1 and BnCHK3, and BnCHK5 are orthologues of AHK2 and AHK3, originally from the B. rapa A genome, respectively. BnCHK1, BnCHK3, and BnCHK5 displayed high affinity for trans-zeatin (1-3nM) in a live-cell competitive receptor assay, but not with other plant hormones (indole acetic acid, GA3, and abscisic acid), confirming the prediction that they are genuine CK receptors. It is shown that BnCHK1 and BnCHK3, and BnCHK5 display distinct preferences for various CK bases and metabolites, characteristic of their AHK counterparts, AHK2 and AHK3, respectively. Interestingly, the AHK2 homologues could be divided into two subfamilies (BnCHK1/BnCK2 and BnCHK3/BnCHK4) that differ in putative transmembrane domain topology and CK binding specificity, thus implying potential functional divergence.

• MeSH
• Brassica napus genetics   metabolism   MeSH
• Phylogeny MeSH
• Molecular Sequence Data MeSH
• Protein Kinases genetics   metabolism   MeSH
• Gene Expression Regulation, Plant * MeSH
• Plant Proteins chemistry   genetics   metabolism   MeSH
• Amino Acid Sequence MeSH
• Sequence Alignment MeSH
• Signal Transduction MeSH
• Protein Structure, Tertiary MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

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