Ama-bryophyte angewona ama-vascular ahlala emakoloni amboze umhlabathi futhi afana namahlathi amancane. Ehlathini langempela, izitshalo ziqhudelana ngokukhanya ezingxenyeni ezihlukene ze-canopy. Uma isitshalo singakutholi ukukhanya kwelanga okwanele, simisa i-lateral branching futhi esikhundleni salokho sikhule sibheke phezulu ukuze sifinyelele ukukhanya kwelanga.
Abacwaningi abavela ku-Gregor Mendel Institute of Molecular Plant Biology (GMI) ye-Austrian Academy of Sciences bathola ukuthi i-liverwort Marchantia polymorpha, umzimba wayo wesitshalo ohluke kakhulu kulawo wezitshalo ezinemithambo yegazi, iphinde iguqule ukwakheka kwayo ekuphenduleni umthunzi. Le mibono emisha mayelana nokuvela kwezindlela zofuzo ezilawula i-branching yanyatheliswa ku Biology yamanje.
Amahlathi enziwe ngezingqimba ezinezingqimba eziningi lapho izihlahla nezinye izitshalo ziqhudelana khona ukuze kukhanye. Ukuntuleka kokukhanya kwelanga kuholela izitshalo ukuthi zilawule amaphethini azo amagatsha ukuze zithande ukukhula okuqondile. Izitshalo ziyawubona umehluko phakathi ilanga eliqondile kanye nomthunzi ngama-phytochromes, ama-photoreceptors akhona emhlabeni wonke umbuso wezitshalo, kusukela ku-algae kuya kuma-bryophyte kuya ezitshalweni eziqhakaza.
"Sekuyisikhathi eside sazi ukuthi ama-phytochromes azisa izitshalo ze-vascular ukuthi ziyeke ukukhula ngokulandelana futhi esikhundleni salokho zikhule ziqonde ukuze zigweme noma zikhule umakhelwane omthunzi," kusho umbhali wokuqala uSusanna Streubel, owayengumlingani we-postdoctoral eqenjini le-Dolan e-GMI. Amagatsha amasha eduze kwesiqu akhiqizwa kuma-lateral meristems, izikhungo ezikhiqizayo zamaseli esiqu sesitshalo athanda ukukhula kwe-lateral. "Le mpendulo emthunzini idinga ukuthi umsebenzi we-lateral meristems uvalwe."
I-Liverworts inciphisa i-branching emthunzini
Abacwaningi bacabanga ukuthi ama-liverworts, ama-bryophyte angewona ama-vascular okucatshangwa ukuthi afana nezitshalo zokuqala ezithatha umhlabathi, nawo anendlela yokujwayela iphethini yawo ye-branching ekushintsheni. izimo zokukhanya. Njengezitshalo ze-vascular, zinama-meristems futhi ziyakwazi ukuhlanganisa. Kodwa-ke, ngokungafani nezitshalo ezithinta imithambo yegazi ezansi kwesihloko noma i-apex, ama-bryophyte atholakala esiqongweni kuphela ngendlela ebizwa ngokuthi i-dichotomous branching.
Abacwaningi be-phenotyped liverworts bathola ukuthi ekukhanyeni okumhlophe okugcwele, umzimba we-flat liverwort, owaziwa nangokuthi i-thallus, uhlanganisa njalo. “Ethunzini elilingiswayo, nokho, ama-liverwort meristem amaningi ahambisana ne-axis eyinhloko yokukhula aye alala futhi awazange akhiqize amagatsha. Ngakho-ke, i-thallus iveze izici zokugwema umthunzi, ”kusho uStreubel. Njengoba ama-liverworts ephinde asebenzise ama-phytochromes, abacwaningi bahlaziye izinguquko ezithinta izakhi zofuzo ezihambisana ne-phytochrome. Babonise ukuthi ngokufanayo nezitshalo zomhlaba ezine-vascular, indlela yokubonisa i-phytochrome iqondisa impendulo yokugwema umthunzi kuma-liverworts.
Ukuziphendukela kwemvelo okuzimele kokulawulwa kwamangqamuzana?
U-Dolan nethimba lakhe bafune izilawuli zofuzo ezengeziwe ze-dichotomous branching kanye nomsebenzi we-meristem ku-M. polymorpha. Ngokuhlola amaphethini wokuvezwa kofuzo ekukhanyeni okumhlophe okugcwele vs. umthunzi, bathole ukuthi i-transcription factor ebizwa ngokuthi i-MpSPL1 kanye ne-liverwort-specific microRNA (miRNA) kunemiphumela ephikisayo ekusebenzeni kwe-meristem: I-MpSPL1 ibalulekile ekwenzeni ama-meristems athule, kuyilapho i-liverwort-specific miRNA iwenza asebenze.
Le miphumela ngokwengxenye iphambene nendlela eyaziwayo yamangqamuzana egatsha eliseduze elilawulwa ukukhanya ku-Arabidopsis thaliana, imodeli efundwa kakhulu yezitshalo zemithambo. Eqinisweni, nakuba izakhi zofuzo ezilawula igatsha elilawulwa ukukhanya e-Arabidopsis nazo zingezomndeni we-SPL futhi ziyizimpokophelo ze-miRNAs, ziqhelelene kakhulu nalezo manje ezikhonjwe ku-liverwort.
Ngale miphumela, ithimba liqagela ukuthi izindlela zamangqamuzana ezilawula i-branching kungenzeka ukuthi zavela ngokuzimela kuma-bryophytes kanye izitshalo zamathambo. "Sekukonke, esikutholile kukhombisa ukuthi indlela elondolozwe ngokwengxenye ye-phytochrome-regulated miRNA kanye ne-SPL gene ilawula ukusebenza kwegatsha emindenini ehlukene ngokuphelele yomhlaba. izitshalo ngezindlela ezihluke kakhulu zokuhlanganisa, ”kusho uMholi Weqembu le-GMI u-Liam Dolan, umbhali ohambisana nalolu cwaningo.