Plants growing in any particular geographical location are exposed to variable and diverse environmental conditions throughout their lifespan. The multifactorial environmental pressure resulted into evolution of plant adaptation and survival strategies requiring ability to integrate multiple signals that combine to yield specific responses. These adaptive responses enable plants to maintain their growth and development while acquiring tolerance to a variety of environmental conditions. An essential signaling cascade that incorporates a wide range of exogenous as well as endogenous stimuli is multistep phosphorelay (MSP). MSP mediates the signaling of essential plant hormones that balance growth, development, and environmental adaptation. Nevertheless, the mechanisms by which specific signals are recognized by a commonly-occurring pathway are not yet clearly understood. Here we summarize our knowledge on the latest model of multistep phosphorelay signaling in plants and the molecular mechanisms underlying the integration of multiple inputs including both hormonal (cytokinins, ethylene and abscisic acid) and environmental (light and temperature) signals into a common pathway. We provide an overview of abiotic stress responses mediated via MSP signaling that are both hormone-dependent and independent. We highlight the mutual interactions of key players such as sensor kinases of various substrate specificities including their downstream targets. These constitute a tightly interconnected signaling network, enabling timely adaptation by the plant to an ever-changing environment. Finally, we propose possible future directions in stress-oriented research on MSP signaling and highlight its potential importance for targeted crop breeding.

• Klíčová slova
• Arabidopsis, abiotic stress, abscisic acid, cytokinin, ethylene, light signaling, multistep phosphorelay (MSP), temperature,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

In plants, the multistep phosphorelay (MSP) pathway mediates a range of regulatory processes, including those activated by cytokinins. The cross talk between cytokinin response and light has been known for a long time. However, the molecular mechanism underlying the interaction between light and cytokinin signaling remains elusive. In the screen for upstream regulators we identified a LONG PALE HYPOCOTYL (LPH) gene whose activity is indispensable for spatiotemporally correct expression of CYTOKININ INDEPENDENT1 (CKI1), encoding the constitutively active sensor His kinase that activates MSP signaling. lph is a new allele of HEME OXYGENASE1 (HY1) that encodes the key protein in the biosynthesis of phytochromobilin, a cofactor of photoconvertible phytochromes. Our analysis confirmed the light-dependent regulation of the CKI1 expression pattern. We show that CKI1 expression is under the control of phytochrome A (phyA), functioning as a dual (both positive and negative) regulator of CKI1 expression, presumably via the phyA-regulated transcription factors (TF) PHYTOCHROME INTERACTING FACTOR3 and CIRCADIAN CLOCK ASSOCIATED1. Changes in CKI1 expression observed in lph/hy1-7 and phy mutants correlate with misregulation of MSP signaling, changed cytokinin sensitivity, and developmental aberrations that were previously shown to be associated with cytokinin and/or CKI1 action. Besides that, we demonstrate a novel role of phyA-dependent CKI1 expression in the hypocotyl elongation and hook development during skotomorphogenesis. Based on these results, we propose that the light-dependent regulation of CKI1 provides a plausible mechanistic link underlying the well-known interaction between light- and cytokinin-controlled plant development.

• MeSH
• Arabidopsis genetika   metabolismus   účinky záření   MeSH
• cytokininy metabolismus   MeSH
• fytochrom A genetika   metabolismus   MeSH
• geneticky modifikované rostliny MeSH
• hemová oxygenasa (decyklizující) genetika   metabolismus   MeSH
• hypokotyl genetika   metabolismus   účinky záření   MeSH
• modely genetické MeSH
• mutace MeSH
• proteinkinasy genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin genetika   účinky záření   MeSH
• signální transdukce genetika   účinky záření   MeSH
• světlo * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• CKI1 protein, Arabidopsis MeSH Prohlížeč
• cytokininy MeSH
• fytochrom A MeSH
• hemová oxygenasa (decyklizující) MeSH
• HY1 protein, Arabidopsis MeSH Prohlížeč
• proteinkinasy MeSH
• proteiny huseníčku MeSH

Banana (Musa sp.) is a vegetatively propagated, low fertility, potentially hybrid and polyploid crop. These qualities make the breeding and targeted genetic improvement of this crop a difficult and long process. The Genome-Wide Association Study (GWAS) approach is becoming widely used in crop plants and has proven efficient to detecting candidate genes for traits of interest, especially in cereals. GWAS has not been applied yet to a vegetatively propagated crop. However, successful GWAS in banana would considerably help unravel the genomic basis of traits of interest and therefore speed up this crop improvement. We present here a dedicated panel of 105 accessions of banana, freely available upon request, and their corresponding GBS data. A set of 5,544 highly reliable markers revealed high levels of admixture in most accessions, except for a subset of 33 individuals from Papua. A GWAS on the seedless phenotype was then successfully applied to the panel. By applying the Mixed Linear Model corrected for both kinship and structure as implemented in TASSEL, we detected 13 candidate genomic regions in which we found a number of genes potentially linked with the seedless phenotype (i.e. parthenocarpy combined with female sterility). An additional GWAS performed on the unstructured Papuan subset composed of 33 accessions confirmed six of these regions as candidate. Out of both sets of analyses, one strong candidate gene for female sterility, a putative orthologous gene to Histidine Kinase CKI1, was identified. The results presented here confirmed the feasibility and potential of GWAS when applied to small sets of banana accessions, at least for traits underpinned by a few loci. As phenotyping in banana is extremely space and time-consuming, this latest finding is of particular importance in the context of banana improvement.

• MeSH
• banánovník anatomie a histologie   genetika   MeSH
• celogenomová asociační studie MeSH
• chov MeSH
• DNA rostlinná genetika   MeSH
• fenotyp MeSH
• genetické markery MeSH
• genotyp MeSH
• jednonukleotidový polymorfismus MeSH
• rostlinné geny MeSH
• semena rostlinná genetika   MeSH
• vazebná nerovnováha MeSH
• zemědělské plodiny anatomie a histologie   genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA rostlinná MeSH
• genetické markery MeSH

Histidine-containing phosphotransfer proteins from Arabidopsis thaliana (AHP1-5) act as intermediates between sensor histidine kinases and response regulators in a signalling system called multi-step phosphorelay (MSP). AHP proteins mediate and potentially integrate various MSP-based signalling pathways (e.g. cytokinin or osmosensing). However, structural information about AHP proteins and their importance in MSP signalling is still lacking. To obtain a deeper insight into the structural basis of AHP-mediated signal transduction, the three-dimensional structure of AHP2 was determined. The AHP2 coding sequence was cloned into pRSET B expression vector, enabling production of AHP2 fused to an N-terminal His tag. AHP2 was expressed in soluble form in Escherichia coli strain BL21 (DE3) pLysS and then purified to homogeneity using metal chelate affinity chromatography and anion-exchange chromatography under reducing conditions. Successful crystallization in a buffer which was optimized for thermal stability yielded crystals that diffracted to 2.5 Å resolution.

• Klíčová slova
• AHP2, Arabidopsis thaliana, histidine phosphotransfer proteins, multi-step phosphorelay,
• MeSH
• Arabidopsis metabolismus   MeSH
• difrakce rentgenového záření MeSH
• elektroforéza v polyakrylamidovém gelu MeSH
• fosfotransferasy chemie   izolace a purifikace   MeSH
• krystalizace MeSH
• proteiny huseníčku chemie   izolace a purifikace   MeSH
• signální transdukce * MeSH
• tranzitní teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• AHP2 protein, Arabidopsis MeSH Prohlížeč
• fosfotransferasy MeSH
• proteiny huseníčku MeSH

The plant hormones cytokinins (CKs) regulate multiple developmental and physiological processes in Arabidopsis (Arabidopsis thaliana). Responses to CKs vary in different organs and tissues (e.g. the response to CKs has been shown to be opposite in shoot and root samples). However, the tissue-specific targets of CKs and the mechanisms underlying such specificity remain largely unclear. Here, we show that the Arabidopsis proteome responds with strong tissue and time specificity to the aromatic CK 6-benzylaminopurine (BAP) and that fast posttranscriptional and/or posttranslational regulation of protein abundance is involved in the contrasting shoot and root proteome responses to BAP. We demonstrate that BAP predominantly regulates proteins involved in carbohydrate and energy metabolism in the shoot as well as protein synthesis and destination in the root. Furthermore, we found that BAP treatment affects endogenous hormonal homeostasis, again with strong tissue specificity. In the shoot, BAP up-regulates the abundance of proteins involved in abscisic acid (ABA) biosynthesis and the ABA response, whereas in the root, BAP rapidly and strongly up-regulates the majority of proteins in the ethylene biosynthetic pathway. This was further corroborated by direct measurements of hormone metabolites, showing that BAP increases ABA levels in the shoot and 1-aminocyclopropane-1-carboxylic acid, the rate-limiting precursor of ethylene biosynthesis, in the root. In support of the physiological importance of these findings, we identified the role of proteins mediating BAP-induced ethylene production, METHIONINE SYNTHASE1 and ACC OXIDASE2, in the early root growth response to BAP.

• MeSH
• 2D gelová elektroforéza MeSH
• Arabidopsis účinky léků   genetika   metabolismus   MeSH
• benzylové sloučeniny MeSH
• biologické modely MeSH
• cytokininy metabolismus   farmakologie   MeSH
• homeostáza účinky léků   MeSH
• kinetin metabolismus   farmakologie   MeSH
• kořeny rostlin účinky léků   genetika   metabolismus   MeSH
• modely genetické MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteom genetika   metabolismus   MeSH
• puriny MeSH
• regulace genové exprese u rostlin účinky léků   MeSH
• regulátory růstu rostlin metabolismus   farmakologie   MeSH
• stanovení celkové genové exprese MeSH
• výhonky rostlin účinky léků   genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• benzylaminopurine MeSH Prohlížeč
• benzylové sloučeniny MeSH
• cytokininy MeSH
• kinetin MeSH
• proteiny huseníčku MeSH
• proteom MeSH
• puriny MeSH
• regulátory růstu rostlin MeSH

The development and activity of the procambium and cambium, which ensure vascular tissue formation, is critical for overall plant architecture and growth. However, little is known about the molecular factors affecting the activity of vascular meristems and vascular tissue formation. Here, we show that the His kinase CYTOKININ-INDEPENDENT1 (CKI1) and the cytokinin receptors ARABIDOPSIS HISTIDINE KINASE2 (AHK2) and AHK3 are important regulators of vascular tissue development in Arabidopsis thaliana shoots. Genetic modifications of CKI1 activity in Arabidopsis cause dysfunction of the two-component signaling pathway and defects in procambial cell maintenance. CKI1 overexpression in protoplasts leads to cytokinin-independent activation of the two-component phosphorelay, and intracellular domains are responsible for the cytokinin-independent activity of CKI1. CKI1 expression is observed in vascular tissues of inflorescence stems, and CKI1 forms homodimers both in vitro and in planta. Loss-of-function ahk2 and ahk3 mutants and plants with reduced levels of endogenous cytokinins show defects in procambium proliferation and an absence of secondary growth. CKI1 overexpression partially rescues ahk2 ahk3 phenotypes in vascular tissue, while the negative mutation CKI1H405Q further accentuates mutant phenotypes. These results indicate that the cytokinin-independent activity of CKI1 and cytokinin-induced AHK2 and AHK3 are important for vascular bundle formation in Arabidopsis.

• MeSH
• Arabidopsis enzymologie   genetika   růst a vývoj   MeSH
• geneticky modifikované rostliny enzymologie   genetika   růst a vývoj   MeSH
• histidinkinasa MeSH
• imunoblotting MeSH
• imunoprecipitace MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• proteinkinasy genetika   fyziologie   MeSH
• proteiny huseníčku genetika   fyziologie   MeSH
• regulace genové exprese u rostlin genetika   fyziologie   MeSH
• výhonky rostlin enzymologie   genetika   růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• AHK2 protein, Arabidopsis MeSH Prohlížeč
• AHK3 protein, Arabidopsis MeSH Prohlížeč
• CKI1 protein, Arabidopsis MeSH Prohlížeč
• histidinkinasa MeSH
• proteinkinasy MeSH
• proteiny huseníčku MeSH