Leaf internal anatomy as a key to photosynthetic performance and stress resilience across plant lineages
| dc.contributor.advisor | Tosens, Tiina (advisor) | |
| dc.contributor.advisor | Niinemets, Ülo (advisor) | |
| dc.contributor.author | Rikisahedew, Jesamine Jöneva | |
| dc.contributor.department | Institute of Agricultural and Environmental Sciences | eng |
| dc.contributor.other | Centritto, Mauro (opponent) | |
| dc.date.accessioned | 2025-11-25T09:12:20Z | |
| dc.date.available | 2025-11-25T09:12:20Z | |
| dc.date.defensed | 2025-12-12 | |
| dc.date.issued | 2025 | |
| dc.description | Doctoral Thesis in Applied Biology. | eng |
| dc.description | Doktoritöö rakendusbioloogia erialal. | eng |
| dc.description.abstract | ABSTRACT. Plants capture carbon from the air and transform it into life-sustaining sugars through photosynthesis. But leaves do far more than just absorb sunlight — they must also defend themselves from herbivores, survive drought and heat, and communicate with their environment. This creates a constant balancing act: carbon invested in protection cannot be used for growth, and structural toughness can make it harder for carbon dioxide to reach the photosynthetic machinery inside the leaf. This thesis explores how different plants solve that challenge by examining the link between leaf anatomy, photosynthesis, and chemical defence. Three very different plant groups were studied to understand this balance across evolution and environments. First, lemongrass — a fragrant grass known for its essential oils — was used to discover how specialised defence cells called idioblasts release stored aromatic compounds when the plant is stressed. The work reveals how leaf structure protects these valuable chemicals until a threat triggers their rapid release. Second, maize and wheat were examined to improve simple and reliable methods for preparing leaf tissues for microscopy. Understanding tiny structural details is essential for breeding crops with more efficient photosynthesis, especially those using the advanced C₄ pathway that helps plants thrive in hot and dry climates. Finally, ancient plants were studied to determine why their leaves have unusually strong walls and tough tissues. These structures help them survive extreme environments, but also restrict the flow of carbon dioxide inside the leaf — limiting photosynthesis. The research identified which microscopic features most strongly regulate this internal carbon transfer. By combining insights from chemical defence, crop efficiency, and plant evolution, this thesis shows that leaf anatomy is a key driver of plant performance. Understanding these internal structures helps explain how plants manage their carbon economy — and offers new ideas for improving resilience and productivity in a changing world. | eng |
| dc.description.abstract | LÜHIKOKKUVÕTE. Taimelehtede sisemine arhitektuur määrab, kui tõhusalt taimed suudavad süsihappegaasi omastada ja end kahjurite või keskkonnastressi eest kaitsta. See mõjutab otseselt taimede kasvukiirust, saagikust ja vastupidavust kliimamuutuste tingimustes. Seetõttu on üha olulisem mõista, kuidas lehe mikroskoopiline ehitus kujundab taime võimet toime tulla väga erinevate keskkonnatingimustega. Käesolevas doktoritöös uuriti kolme väga erinevat taimede rühma: • aromaatseid heintaimi, mis talletavad biogeenseid lenduvaid ühendeid spetsiaalsetes rakkudes. • C3 ja C4 metabolismiga põllukultuure. • Iidseid paljasseemne taimi. Esimeses uuringus näidati, et eeterlikke õlisid talletavad rakud – idioblastid – aitavad taimel stressile kiiresti reageerida, vabastades hetkega kaitselõhnu. See tähendab, et isegi tugeva stressisignaali korral ei pea taim volatiilseid ühendeid nullist sünteesima – need on juba säilitusrakkudes hoiul ja valmis koheselt kasutamiseks. Teises uuringus kohandati mikroskoopiameetodeid erinevatele taimerühmadele. See avardab oluliselt võimalusi uurida fotosünteesi parendamise strateegiaid ning leheanatoomia mõju süsinikusidumisele erinevates C3 taimesühmades. Kolmandas uuringus uuriti fotosünteesipiiravaid tegureid iidsetes paljasseemnetaimedes. Tulemused näitasid, et Fotosüntees on oluliselt piiratud mesofüllisisese süsihappegaasi difusiooni poolt. Kokkuvõttes näitab see töö, et taimede võime toimida nii tõhusate süsinikusidujate kui ka tugevate kaitsjatena sõltub pidevast tasakaalust – sellest, kuidas nad jagavad oma süsinikuvaru kasvamiseks, fotosünteesiks ja keemiliseks kaitseks. Neid lõivsuhete mehhanisme paremini mõistes saame tulevikus nii aretada kliimamuutustele vastupidavamaid põllukultuure kui ka täpsemalt hinnata taimede rolli Maa süsinikuringes. | est |
| dc.description.sponsorship | Publication of this thesis was supported by the Estonian University of Life Sciences. | eng |
| dc.description.sponsorship | This study was funded by the following institutions under projects P200197 and TK200U1. | eng |
| dc.identifier.citation | Rikisahedew, J. J. (2025). Leaf internal anatomy as a key to photosynthetic performance and stress resilience across plant lineages [Estonian University of Life Sciences]. https://doi.org/10.15159/EMU.167 | eng |
| dc.identifier.isbn | 978-9916-91-051-1 (pdf) | |
| dc.identifier.issn | 2382-7076 | |
| dc.identifier.uri | http://hdl.handle.net/10492/10185 | |
| dc.identifier.uri | https://doi.org/10.15159/emu.167 | |
| dc.publisher | Estonian University of Life Sciences | |
| dc.relation.ispartofseries | Doctoral Theses of the Estonian University of Life Sciences | eng |
| dc.relation.ispartofseries | Eesti Maaülikooli doktoritööd | est |
| dc.rights | © Jesamine Jöneva Rikisahedew, 2025 | |
| dc.rights | info:eu-repo/semantics/openAccess | eng |
| dc.rights.uri | https://www.riigiteataja.ee/en/eli/ee/Riigikogu/act/519062017005/consolide | est |
| dc.subject | leaf | |
| dc.subject | plant anatomy | |
| dc.subject | photosynthesis | |
| dc.subject | stress resilience | |
| dc.subject | dissertations | |
| dc.subject | Green University (thesis is related to EMÜ Green University iniciative’s aims) | |
| dc.title | Leaf internal anatomy as a key to photosynthetic performance and stress resilience across plant lineages | |
| dc.title.alternative | Lehe sisemine anatoomia kui fotosünteesi võimekuse ja stressitaluvuse võti taimeliikide lõikes | |
| dc.type | Doctoral Thesis | |
| dc.type.qualificationname | PhD |
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