Paula Elomaa - Academia.edu (original) (raw)

Papers by Paula Elomaa

Plant Molecular Biology, May 1, 1993

Cloning of cDNA coding for dihydroflavonol-4-reductase (DFR) and characterization of dfr expressi... more Cloning of cDNA coding for dihydroflavonol-4-reductase (DFR) and characterization of dfr expression in the corollas of Gerbera hybrida var.

Suomen maataloustieteellisen seuran tiedote, Jan 31, 2010

Kasvien kukintaa säätelevät sekä ulkoiset (ympäristöolosuhteet) että sisäiset tekijät (kasvin keh... more Kasvien kukintaa säätelevät sekä ulkoiset (ympäristöolosuhteet) että sisäiset tekijät (kasvin kehitysvaihe). Näiden tekijöiden vaikutusta kukinnan alkamiseen on tutkittu paljon erityisesti lituruohon (Arabidopsis thaliana (L.) Heyhn.), avulla. Lituruoholla kukintaa säätelevät useat reitit, kuten esimerkiksi päivänpituus-, hormoni-, vernalisaatio-ja autonominen reitti. Reitit muodostavat geeniverkoston, joka säätelee kukintaingeraattorigeenien FT ja SOC1 kautta kukkameristeemin identiteettigeenejä LFY ja AP1. Päivänpituusreitti edistää kukintaa aktivoimalla FT:n ilmenemistä, kun taas hormoni-, vernalisaatio-ja autonominen reitti edistävät kukintaa estämällä kahden kukintaa negatiivisesti säätelevän geenin, FLC:n ja SVP:n, ilmenemistä. Yhteistä SOC1:lle, FLC:lle ja SVP:lle on se, että ne kaikki kuuluvat laajaan MADS-boxgeeniperheeseen. MADS-geenien koodaamat proteiinit säätelevät kohdegeeniensä toimintaa sitoutumalla niiden DNA:han. Lisäksi MADS-proteiinit pystyvät muodostamaan komplekseja sekä itsensä että muiden MADS-proteiinien kanssa. Esimerkiksi SOC1 aktivoi LFY:ä sitoutumalla sen säätelyalueeseen, mutta pystyy siirtymään tumaan vain vuorovaikutuksessa toisen MADS-proteiinin kanssa. Vastaavasti FLC ja SVP estävät SOC1:n ilmenemistä sitoutumalla sen säätelyalueeseen keskinäisessä vuorovaikutuksessa. MADS-proteiinit ja niiden vuorovaikutukset sekä toiminta ovat varsin säilyneitä eri kasvilajien välillä, joskin keskeinen kukintaa estävä MADS-geeni FLC on tunnistettu vain ristikukkaisissa lajeissa. Ahomansikka on, toisin kuin lituruoho, monivuotinen lyhyenpäivänkasvi. Tutkimme mansikan kukinnan säätelyä käyttämällä ahomansikkaa mallikasvina. Ahomansikalta tunnetaan villityypin lisäksi useita jatkuvasatoisia muunnoksia. Näiden avulla olemme identifioineet mahdollisia kukintaan liittyviä kandidaattigeenejä, joiden toimintaa mansikalla voidaan tutkia siirtogeenisten mansikkalinjojen avulla. Tutkimme ahomansikan SOC1:n roolia kukinnan säätelyssä käyttämällä geenien ylituotto-ja hiljentämistekniikkaa Hawaii-4-genotyypillä. Olemme tuottaneet agrobakteerivälitteisen geeninsiirron avulla useita ylituotto-ja hiljennyslinjoja, joiden kukintaominaisuuksissa näkyy muutoksia.

Acta horticulturae, Oct 1, 2001

TH (1999). Organ identity genes and modified patterns of flower development in Gerbera hybrida (A... more TH (1999). Organ identity genes and modified patterns of flower development in Gerbera hybrida (Asteraceae). Plant J. 17: 51-62. *Joint first authors.

Plant Molecular Biology, Aug 1, 1995

In the ornamental cut flower plant Gerbera hybrida the spatial distribution of regulatory molecul... more In the ornamental cut flower plant Gerbera hybrida the spatial distribution of regulatory molecules characteristic of differentiation of the composite inflorescence is visualized as the various patterns of anthocyanin pigmentation of different varieties. In order to identify genes that the plant can regulate according to these anatomical patterns, we have analysed gene expression affecting two enzymatic steps, chalcone synthase (CH S) and dihydroflavonol-4-reductase (DFR), in five gerbera varieties with spatially restricted anthocyanin pigmentation patterns. The dfr expression profiles vary at the levels of floral organ, flower type and region within corolla during inflorescence development according to the anthocyanin pigmentation of the cultivars. In contrast, chs expression, although regulated in a tissue-specific manner during inflorescence development, varies only occasionally. The variation in the dfr expression profiles between the varieties reveals spatially specific gene regulation that senses the differentiation events characteristic of the composite inflorescence.

The Plant Cell, Oct 1, 2000

Despite the differences in flower form, the underlying mechanism in determining the identity of f... more Despite the differences in flower form, the underlying mechanism in determining the identity of floral organs is largely conserved among different angiosperms, but the details of how the functions of A, B, and C are specified varies greatly among plant species. Here, we report functional analysis of a Gerbera MADS box gene, GRCD1 , which is orthologous to AGL2-like MADS box genes. Members of this group of genes are being reported in various species in growing numbers, but their functions remained largely unsettled. GRCD1 expression is detected in all four whorls, but the strongest signal is seen in the developing stamen and carpel. Downregulating GRCD1 expression by antisense transformation revealed that lack of GRCD1 caused homeotic changes in one whorl only: sterile staminodes, which normally develop in whorl 3 of marginal female florets, were changed into petals. This indicates that the GRCD1 gene product is active in determining stamen identity. Transgenic downregulation of GRCD1 causes a homeotic change similar to that in the downregulation of the Gerbera C function genes GAGA1 and GAGA2 , but one that is limited to whorl 3. Downregulation of GRCD1 expression does not reduce expression of GAGA1 or GAGA2 , or vice versa; and in yeast two-hybrid analysis, GRCD1 is able to interact with GAGA1 and GAGA2. We propose that a heterodimer between the GRCD1 and GAGA1/2 gene products is needed to fulfill the C function in whorl 3 in Gerbera.

Acta horticulturae, Oct 1, 2001

We have identified a new chalcone synthase (CHS)-like enzyme, 2-pyrone synthase (2PS), in Gerbera... more We have identified a new chalcone synthase (CHS)-like enzyme, 2-pyrone synthase (2PS), in Gerbera hybrida var. Regina (Asteraceae). While 2PS has amino acid sequence identity of ~70% to CHS enzymes, it has a novel substrate specificity and uses acetyl-CoA as a starter substrate. Transgenic 2PS antisense gerbera plants with very low 2PS activity lack two abundant secondary metabolites found in control plants, gerberin and parasorboside. The antisense plants show susceptibility for the mold Botrytis cinerea and insect pests. Statistical analyses revealed significant difference between resistent and sensitive G. hybrida varieties when concerning the total amount of gerberin and parasorboside.

Plant Molecular Biology, Nov 1, 1994

We are examining the floral organ differentiation in Compositae by isolating and characterizing c... more We are examining the floral organ differentiation in Compositae by isolating and characterizing corolla abundant genes. Differential screening of a cDNA library made from the ray floret corolla of Gerbera hybrida var. Regina revealed an abundant cDNA clone which is expressed in the corolla but not in leaves. This cDNA (gltp1) codes for a polypeptide similar to non-specific lipid transfer proteins of the plants. The gltp1 gene is expressed only in the corolla and carpels and is developmentally regulated during corolla development. The gltp1 mRNA accumulates both in epidermal cell layers and in the mesophyll of the corolla. In the stylar part of the carpel, the gltp1 mRNA can be detected in the epidermal and in parenchymal cells but not in the transmitting tissue. Analogous patterns of gltp1 expression in the corolla and carpel may indicate that similar genetic programmes operates during the development of these two tissues.

Proceedings of the National Academy of Sciences of the United States of America, Oct 25, 2004

Reproductive transition, inflorescence architecture, meristem patterning, and floral organ identi... more Reproductive transition, inflorescence architecture, meristem patterning, and floral organ identity have been studied as distinct research areas in plant science. By using the ornamental plant Gerbera, we demonstrate that all of these keystone aspects of reproductive meristematic fate are integrated genetically by a single SEPALLATA-like MADS-box gene from a functional class designated previously as ''floral homeotic'' or ''organ identity.'' This extended regulatory network has not been elaborated in the model plant systems, which have a floral design and inflorescencedeterminacy state that obscures these relationships.

Plant Physiology, Sep 8, 2020

The large sunflower family, Asteraceae, is characterized by compressed, flower-like inflorescence... more The large sunflower family, Asteraceae, is characterized by compressed, flower-like inflorescences that may bear phenotypically distinct flower types. The CYCLOIDEA/TEOSINTE BRANCHED1 (CYC/TB1)-like transcription factors (TFs) belonging to the TEOSINTE BRANCHED 1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) protein family are known to regulate bilateral symmetry in single flowers. In Asteraceae, they function at the inflorescence level, and were recruited to define differential flower type identities. Here, we identified upstream regulators of GhCYC3, a gene that specifies ray flower identity at the flower head margin in the model plant Gerbera hybrida. We discovered a previously unidentified expression domain and functional role for the paralogous CINCINNATA-like (CIN) TCP proteins. They function upstream of GhCYC3 and affect the developmental delay of marginal ray primordia during their early ontogeny. At the level of single flowers, the Asteraceae CYC genes show a unique function in regulating the elongation of showy ventral ligules that play a major role in pollinator attraction. We discovered that during ligule development, the E class MADS-box TF GRCD5 activates GhCYC3 expression. We propose that the C class MADS-box TF GAGA1 contributes to stamen development upstream of GhCYC3. Our data demonstrate how interactions among and between the conserved floral regulators, TCP and MADS-box TFs, contribute to the evolution of the elaborate inflorescence architecture of Asteraceae.

Journal of experimental botany, Jan 30, 2017

I could have selected my favourite flowering image from thousands of astonishing images that have... more I could have selected my favourite flowering image from thousands of astonishing images that have captured the geometric regularity of head-like inflorescences in Asteraceae. These unique inflorescences pack hundreds of flowers into precise spirals whose numbers follow a famous mathematical rule. Meanwhile, the whole structure may mislead a layman (or a pollinator) by mimicking a single solitary flower although it consists of morphologically and functionally distinct types of flowers.

Suomen Maataloustieteellisen Seuran Tiedote, 2010

Valo on keskeinen kasvien kehitystä, kuten kukintaan virittymistä, ohjaava signaali. Valoreseptor... more Valo on keskeinen kasvien kehitystä, kuten kukintaan virittymistä, ohjaava signaali. Valoreseptorientoimintaa ei tunneta geneettisellä tasolla tarkasti. Pitkänpäivänkasvi lituruoholla (Arabidopsis thaliana (L.)Heynh.) kukinta-aikaa säätelevät valon spektrin sininen, punainen ja kaukopunainen aallonpituusalue.Kaukopunainen ja sininen valo edistävät ja punainen valo estää kukintaa. Valodiodeilla (light emittingdiodes, LED) valoa voidaan tuottaa hyvin kapealla aallonpituusalueella ja muuttaa valon laatua kasvinkasvun ja kehityksen ohjaamiseksi halutulla tavalla.Ahomansikalla (Fragaria vesca L.) punaisen, kaukopunaisen ja sinisen valon vaikutuksia kukintaanei ole tutkittu aikaisemmin. Ahomansikan kukinta indusoituu lyhyenpäivän olosuhteissa. Ahomansikaltatunnetaan kuitenkin myös päivänpituusmutantteja. Rönsytön lajike Baron Solemacher sekä rönsyjämuodostava lajike Hawaii-4 virittyvät kukintaan pitkänpäivän olosuhteissa. Tutkimuksen tavoitteena onselvittää valon laadun vaikutusta ahomans...

Suomen Maataloustieteellisen Seuran Tiedote, 2010

Gerbera hybrida (sädelatva) on suosittu koristekasvi. Terälehtien värit ovat peräisin vesiliukois... more Gerbera hybrida (sädelatva) on suosittu koristekasvi. Terälehtien värit ovat peräisin vesiliukoisistaantosyaaneista, jotka ovat sekundäärimetabolian tuotteita. Tutkiessamme tätä metaboliareittiä, löysimmesen läheltä haaran, joka johtaa karvaan makuisiin yhdisteisiin, gerberiiniin ja parasorbosidiin.Näiden karvasaineiden merkitys gerberalle on ollut tuntematon.Gerberan karvasaineiden biosynteesiin vaikutettiin geenitekniikan keinoin hiljentämällä keskeisen2PS-geenin toiminta. Anti-2PS-linjojen siirtogeenisiin gerberoihin ei gerberiiniä ja parasorbosidiasynny, vaan ne maistuvat tavanomaiseen gerberaan verrattuna makealta. Epäily näiden makealta maistuvienkasvien herkkyydestä hyönteisherbivoriaan heräsi kasvihuonehavaintojemme perusteella.Teimme erilaisia syöttö- ja munintakokeita, joissa hyönteiset saivat valita karvasaineettoman jakarvasainetta sisältävän gerberan välillä. Karvasaineilla oli voimakas estävä vaikutus täplätupsukkaan(Orgyia antiqua) ja krysanteemiyökkösen (Spodoptera l...

Horticulture Research, 2018

Inflorescences in the Asteraceae plant family, flower heads, or capitula, mimic single flowers bu... more Inflorescences in the Asteraceae plant family, flower heads, or capitula, mimic single flowers but are highly compressed structures composed of multiple flowers. This transference of a flower-like appearance into an inflorescence level is considered as the key innovation for the rapid tribal radiation of Asteraceae. Recent molecular data indicate that Asteraceae flower heads resemble single flowers not only morphologically but also at molecular level. We summarize this data giving examples of how rewiring of conserved floral regulators have led to evolution of morphological innovations in Asteraceae. Functional diversification of the highly conserved flower meristem identity regulator LEAFY has shown a major role in the evolution of the capitulum architecture. Furthermore, gene duplication and subsequent sub-and neofunctionalization of SEPALLATA-and CYCLOIDEA-like genes in Asteraceae have been shown to contribute to meristem determinacy, as well as flower type differentiation-key traits that specify this large family. Future challenge is to integrate genomic, as well as evolutionary developmental studies in a wider selection of Asteraceae species to understand the detailed gene regulatory networks behind the elaborate inflorescence architecture, and to promote our understanding of how changes in regulatory mechanisms shape development.

Nature genetics, Jan 8, 2017

Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 yea... more Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 year. Its rapid life cycle, small (440-Mb) genome, and advanced germplasm resources make birch an attractive model for forest biotechnology. We assembled and chromosomally anchored the nuclear genome of an inbred B. pendula individual. Gene duplicates from the paleohexaploid event were enriched for transcriptional regulation, whereas tandem duplicates were overrepresented by environmental responses. Population resequencing of 80 individuals showed effective population size crashes at major points of climatic upheaval. Selective sweeps were enriched among polyploid duplicates encoding key developmental and physiological triggering functions, suggesting that local adaptation has tuned the timing of and cross-talk between fundamental plant processes. Variation around the tightly-linked light response genes PHYC and FRS10 correlated with latitude and longitude and temperature, and with precipit...

Plant physiology, Sep 5, 2016

The evolutionary success of Asteraceae, the largest family of flowering plants, has been attribut... more The evolutionary success of Asteraceae, the largest family of flowering plants, has been attributed to the unique inflorescence architecture of the family, which superficially resembles an individual flower. Here we show that Asteraceae inflorescences (flower heads, or capitula) resemble solitary flowers not only morphologically but also at the molecular level. By conducting functional analyses for orthologs of the flower meristem identity (FMI) genes LEAFY (LFY) and UNUSUAL FLORAL ORGANS (UFO) in Gerbera hybrida (Gh), we show that GhUFO is the master regulator of FMI, while GhLFY has evolved a novel, homeotic function during the evolution of head-like inflorescences. Resembling LFY expression in a single flower meristem, uniform expression of GhLFY in the inflorescence meristem defines the capitulum as a determinate structure that can assume floral fate upon ectopic GhUFO expression. We also show that GhLFY uniquely regulates the ontogeny of outer, expanded ray flowers but not inne...

Plant Molecular Biology, May 1, 1993

Cloning of cDNA coding for dihydroflavonol-4-reductase (DFR) and characterization of dfr expressi... more Cloning of cDNA coding for dihydroflavonol-4-reductase (DFR) and characterization of dfr expression in the corollas of Gerbera hybrida var.

Suomen maataloustieteellisen seuran tiedote, Jan 31, 2010

Kasvien kukintaa säätelevät sekä ulkoiset (ympäristöolosuhteet) että sisäiset tekijät (kasvin keh... more Kasvien kukintaa säätelevät sekä ulkoiset (ympäristöolosuhteet) että sisäiset tekijät (kasvin kehitysvaihe). Näiden tekijöiden vaikutusta kukinnan alkamiseen on tutkittu paljon erityisesti lituruohon (Arabidopsis thaliana (L.) Heyhn.), avulla. Lituruoholla kukintaa säätelevät useat reitit, kuten esimerkiksi päivänpituus-, hormoni-, vernalisaatio-ja autonominen reitti. Reitit muodostavat geeniverkoston, joka säätelee kukintaingeraattorigeenien FT ja SOC1 kautta kukkameristeemin identiteettigeenejä LFY ja AP1. Päivänpituusreitti edistää kukintaa aktivoimalla FT:n ilmenemistä, kun taas hormoni-, vernalisaatio-ja autonominen reitti edistävät kukintaa estämällä kahden kukintaa negatiivisesti säätelevän geenin, FLC:n ja SVP:n, ilmenemistä. Yhteistä SOC1:lle, FLC:lle ja SVP:lle on se, että ne kaikki kuuluvat laajaan MADS-boxgeeniperheeseen. MADS-geenien koodaamat proteiinit säätelevät kohdegeeniensä toimintaa sitoutumalla niiden DNA:han. Lisäksi MADS-proteiinit pystyvät muodostamaan komplekseja sekä itsensä että muiden MADS-proteiinien kanssa. Esimerkiksi SOC1 aktivoi LFY:ä sitoutumalla sen säätelyalueeseen, mutta pystyy siirtymään tumaan vain vuorovaikutuksessa toisen MADS-proteiinin kanssa. Vastaavasti FLC ja SVP estävät SOC1:n ilmenemistä sitoutumalla sen säätelyalueeseen keskinäisessä vuorovaikutuksessa. MADS-proteiinit ja niiden vuorovaikutukset sekä toiminta ovat varsin säilyneitä eri kasvilajien välillä, joskin keskeinen kukintaa estävä MADS-geeni FLC on tunnistettu vain ristikukkaisissa lajeissa. Ahomansikka on, toisin kuin lituruoho, monivuotinen lyhyenpäivänkasvi. Tutkimme mansikan kukinnan säätelyä käyttämällä ahomansikkaa mallikasvina. Ahomansikalta tunnetaan villityypin lisäksi useita jatkuvasatoisia muunnoksia. Näiden avulla olemme identifioineet mahdollisia kukintaan liittyviä kandidaattigeenejä, joiden toimintaa mansikalla voidaan tutkia siirtogeenisten mansikkalinjojen avulla. Tutkimme ahomansikan SOC1:n roolia kukinnan säätelyssä käyttämällä geenien ylituotto-ja hiljentämistekniikkaa Hawaii-4-genotyypillä. Olemme tuottaneet agrobakteerivälitteisen geeninsiirron avulla useita ylituotto-ja hiljennyslinjoja, joiden kukintaominaisuuksissa näkyy muutoksia.

Acta horticulturae, Oct 1, 2001

TH (1999). Organ identity genes and modified patterns of flower development in Gerbera hybrida (A... more TH (1999). Organ identity genes and modified patterns of flower development in Gerbera hybrida (Asteraceae). Plant J. 17: 51-62. *Joint first authors.

Plant Molecular Biology, Aug 1, 1995

In the ornamental cut flower plant Gerbera hybrida the spatial distribution of regulatory molecul... more In the ornamental cut flower plant Gerbera hybrida the spatial distribution of regulatory molecules characteristic of differentiation of the composite inflorescence is visualized as the various patterns of anthocyanin pigmentation of different varieties. In order to identify genes that the plant can regulate according to these anatomical patterns, we have analysed gene expression affecting two enzymatic steps, chalcone synthase (CH S) and dihydroflavonol-4-reductase (DFR), in five gerbera varieties with spatially restricted anthocyanin pigmentation patterns. The dfr expression profiles vary at the levels of floral organ, flower type and region within corolla during inflorescence development according to the anthocyanin pigmentation of the cultivars. In contrast, chs expression, although regulated in a tissue-specific manner during inflorescence development, varies only occasionally. The variation in the dfr expression profiles between the varieties reveals spatially specific gene regulation that senses the differentiation events characteristic of the composite inflorescence.

The Plant Cell, Oct 1, 2000

Despite the differences in flower form, the underlying mechanism in determining the identity of f... more Despite the differences in flower form, the underlying mechanism in determining the identity of floral organs is largely conserved among different angiosperms, but the details of how the functions of A, B, and C are specified varies greatly among plant species. Here, we report functional analysis of a Gerbera MADS box gene, GRCD1 , which is orthologous to AGL2-like MADS box genes. Members of this group of genes are being reported in various species in growing numbers, but their functions remained largely unsettled. GRCD1 expression is detected in all four whorls, but the strongest signal is seen in the developing stamen and carpel. Downregulating GRCD1 expression by antisense transformation revealed that lack of GRCD1 caused homeotic changes in one whorl only: sterile staminodes, which normally develop in whorl 3 of marginal female florets, were changed into petals. This indicates that the GRCD1 gene product is active in determining stamen identity. Transgenic downregulation of GRCD1 causes a homeotic change similar to that in the downregulation of the Gerbera C function genes GAGA1 and GAGA2 , but one that is limited to whorl 3. Downregulation of GRCD1 expression does not reduce expression of GAGA1 or GAGA2 , or vice versa; and in yeast two-hybrid analysis, GRCD1 is able to interact with GAGA1 and GAGA2. We propose that a heterodimer between the GRCD1 and GAGA1/2 gene products is needed to fulfill the C function in whorl 3 in Gerbera.

Acta horticulturae, Oct 1, 2001

We have identified a new chalcone synthase (CHS)-like enzyme, 2-pyrone synthase (2PS), in Gerbera... more We have identified a new chalcone synthase (CHS)-like enzyme, 2-pyrone synthase (2PS), in Gerbera hybrida var. Regina (Asteraceae). While 2PS has amino acid sequence identity of ~70% to CHS enzymes, it has a novel substrate specificity and uses acetyl-CoA as a starter substrate. Transgenic 2PS antisense gerbera plants with very low 2PS activity lack two abundant secondary metabolites found in control plants, gerberin and parasorboside. The antisense plants show susceptibility for the mold Botrytis cinerea and insect pests. Statistical analyses revealed significant difference between resistent and sensitive G. hybrida varieties when concerning the total amount of gerberin and parasorboside.

Plant Molecular Biology, Nov 1, 1994

We are examining the floral organ differentiation in Compositae by isolating and characterizing c... more We are examining the floral organ differentiation in Compositae by isolating and characterizing corolla abundant genes. Differential screening of a cDNA library made from the ray floret corolla of Gerbera hybrida var. Regina revealed an abundant cDNA clone which is expressed in the corolla but not in leaves. This cDNA (gltp1) codes for a polypeptide similar to non-specific lipid transfer proteins of the plants. The gltp1 gene is expressed only in the corolla and carpels and is developmentally regulated during corolla development. The gltp1 mRNA accumulates both in epidermal cell layers and in the mesophyll of the corolla. In the stylar part of the carpel, the gltp1 mRNA can be detected in the epidermal and in parenchymal cells but not in the transmitting tissue. Analogous patterns of gltp1 expression in the corolla and carpel may indicate that similar genetic programmes operates during the development of these two tissues.

Proceedings of the National Academy of Sciences of the United States of America, Oct 25, 2004

Reproductive transition, inflorescence architecture, meristem patterning, and floral organ identi... more Reproductive transition, inflorescence architecture, meristem patterning, and floral organ identity have been studied as distinct research areas in plant science. By using the ornamental plant Gerbera, we demonstrate that all of these keystone aspects of reproductive meristematic fate are integrated genetically by a single SEPALLATA-like MADS-box gene from a functional class designated previously as ''floral homeotic'' or ''organ identity.'' This extended regulatory network has not been elaborated in the model plant systems, which have a floral design and inflorescencedeterminacy state that obscures these relationships.

Plant Physiology, Sep 8, 2020

The large sunflower family, Asteraceae, is characterized by compressed, flower-like inflorescence... more The large sunflower family, Asteraceae, is characterized by compressed, flower-like inflorescences that may bear phenotypically distinct flower types. The CYCLOIDEA/TEOSINTE BRANCHED1 (CYC/TB1)-like transcription factors (TFs) belonging to the TEOSINTE BRANCHED 1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) protein family are known to regulate bilateral symmetry in single flowers. In Asteraceae, they function at the inflorescence level, and were recruited to define differential flower type identities. Here, we identified upstream regulators of GhCYC3, a gene that specifies ray flower identity at the flower head margin in the model plant Gerbera hybrida. We discovered a previously unidentified expression domain and functional role for the paralogous CINCINNATA-like (CIN) TCP proteins. They function upstream of GhCYC3 and affect the developmental delay of marginal ray primordia during their early ontogeny. At the level of single flowers, the Asteraceae CYC genes show a unique function in regulating the elongation of showy ventral ligules that play a major role in pollinator attraction. We discovered that during ligule development, the E class MADS-box TF GRCD5 activates GhCYC3 expression. We propose that the C class MADS-box TF GAGA1 contributes to stamen development upstream of GhCYC3. Our data demonstrate how interactions among and between the conserved floral regulators, TCP and MADS-box TFs, contribute to the evolution of the elaborate inflorescence architecture of Asteraceae.

Journal of experimental botany, Jan 30, 2017

I could have selected my favourite flowering image from thousands of astonishing images that have... more I could have selected my favourite flowering image from thousands of astonishing images that have captured the geometric regularity of head-like inflorescences in Asteraceae. These unique inflorescences pack hundreds of flowers into precise spirals whose numbers follow a famous mathematical rule. Meanwhile, the whole structure may mislead a layman (or a pollinator) by mimicking a single solitary flower although it consists of morphologically and functionally distinct types of flowers.

Suomen Maataloustieteellisen Seuran Tiedote, 2010

Valo on keskeinen kasvien kehitystä, kuten kukintaan virittymistä, ohjaava signaali. Valoreseptor... more Valo on keskeinen kasvien kehitystä, kuten kukintaan virittymistä, ohjaava signaali. Valoreseptorientoimintaa ei tunneta geneettisellä tasolla tarkasti. Pitkänpäivänkasvi lituruoholla (Arabidopsis thaliana (L.)Heynh.) kukinta-aikaa säätelevät valon spektrin sininen, punainen ja kaukopunainen aallonpituusalue.Kaukopunainen ja sininen valo edistävät ja punainen valo estää kukintaa. Valodiodeilla (light emittingdiodes, LED) valoa voidaan tuottaa hyvin kapealla aallonpituusalueella ja muuttaa valon laatua kasvinkasvun ja kehityksen ohjaamiseksi halutulla tavalla.Ahomansikalla (Fragaria vesca L.) punaisen, kaukopunaisen ja sinisen valon vaikutuksia kukintaanei ole tutkittu aikaisemmin. Ahomansikan kukinta indusoituu lyhyenpäivän olosuhteissa. Ahomansikaltatunnetaan kuitenkin myös päivänpituusmutantteja. Rönsytön lajike Baron Solemacher sekä rönsyjämuodostava lajike Hawaii-4 virittyvät kukintaan pitkänpäivän olosuhteissa. Tutkimuksen tavoitteena onselvittää valon laadun vaikutusta ahomans...

Suomen Maataloustieteellisen Seuran Tiedote, 2010

Gerbera hybrida (sädelatva) on suosittu koristekasvi. Terälehtien värit ovat peräisin vesiliukois... more Gerbera hybrida (sädelatva) on suosittu koristekasvi. Terälehtien värit ovat peräisin vesiliukoisistaantosyaaneista, jotka ovat sekundäärimetabolian tuotteita. Tutkiessamme tätä metaboliareittiä, löysimmesen läheltä haaran, joka johtaa karvaan makuisiin yhdisteisiin, gerberiiniin ja parasorbosidiin.Näiden karvasaineiden merkitys gerberalle on ollut tuntematon.Gerberan karvasaineiden biosynteesiin vaikutettiin geenitekniikan keinoin hiljentämällä keskeisen2PS-geenin toiminta. Anti-2PS-linjojen siirtogeenisiin gerberoihin ei gerberiiniä ja parasorbosidiasynny, vaan ne maistuvat tavanomaiseen gerberaan verrattuna makealta. Epäily näiden makealta maistuvienkasvien herkkyydestä hyönteisherbivoriaan heräsi kasvihuonehavaintojemme perusteella.Teimme erilaisia syöttö- ja munintakokeita, joissa hyönteiset saivat valita karvasaineettoman jakarvasainetta sisältävän gerberan välillä. Karvasaineilla oli voimakas estävä vaikutus täplätupsukkaan(Orgyia antiqua) ja krysanteemiyökkösen (Spodoptera l...

Horticulture Research, 2018

Inflorescences in the Asteraceae plant family, flower heads, or capitula, mimic single flowers bu... more Inflorescences in the Asteraceae plant family, flower heads, or capitula, mimic single flowers but are highly compressed structures composed of multiple flowers. This transference of a flower-like appearance into an inflorescence level is considered as the key innovation for the rapid tribal radiation of Asteraceae. Recent molecular data indicate that Asteraceae flower heads resemble single flowers not only morphologically but also at molecular level. We summarize this data giving examples of how rewiring of conserved floral regulators have led to evolution of morphological innovations in Asteraceae. Functional diversification of the highly conserved flower meristem identity regulator LEAFY has shown a major role in the evolution of the capitulum architecture. Furthermore, gene duplication and subsequent sub-and neofunctionalization of SEPALLATA-and CYCLOIDEA-like genes in Asteraceae have been shown to contribute to meristem determinacy, as well as flower type differentiation-key traits that specify this large family. Future challenge is to integrate genomic, as well as evolutionary developmental studies in a wider selection of Asteraceae species to understand the detailed gene regulatory networks behind the elaborate inflorescence architecture, and to promote our understanding of how changes in regulatory mechanisms shape development.

Nature genetics, Jan 8, 2017

Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 yea... more Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 year. Its rapid life cycle, small (440-Mb) genome, and advanced germplasm resources make birch an attractive model for forest biotechnology. We assembled and chromosomally anchored the nuclear genome of an inbred B. pendula individual. Gene duplicates from the paleohexaploid event were enriched for transcriptional regulation, whereas tandem duplicates were overrepresented by environmental responses. Population resequencing of 80 individuals showed effective population size crashes at major points of climatic upheaval. Selective sweeps were enriched among polyploid duplicates encoding key developmental and physiological triggering functions, suggesting that local adaptation has tuned the timing of and cross-talk between fundamental plant processes. Variation around the tightly-linked light response genes PHYC and FRS10 correlated with latitude and longitude and temperature, and with precipit...

Plant physiology, Sep 5, 2016

The evolutionary success of Asteraceae, the largest family of flowering plants, has been attribut... more The evolutionary success of Asteraceae, the largest family of flowering plants, has been attributed to the unique inflorescence architecture of the family, which superficially resembles an individual flower. Here we show that Asteraceae inflorescences (flower heads, or capitula) resemble solitary flowers not only morphologically but also at the molecular level. By conducting functional analyses for orthologs of the flower meristem identity (FMI) genes LEAFY (LFY) and UNUSUAL FLORAL ORGANS (UFO) in Gerbera hybrida (Gh), we show that GhUFO is the master regulator of FMI, while GhLFY has evolved a novel, homeotic function during the evolution of head-like inflorescences. Resembling LFY expression in a single flower meristem, uniform expression of GhLFY in the inflorescence meristem defines the capitulum as a determinate structure that can assume floral fate upon ectopic GhUFO expression. We also show that GhLFY uniquely regulates the ontogeny of outer, expanded ray flowers but not inne...