Why is C4 photosynthesis so rare in trees?
| Autor: | Margaret J. Sporck-Koehler, Lawren Sack, Marjorie R. Lundgren, Sophie N R Young |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
0106 biological sciences
0301 basic medicine Expert View food.ingredient C4 photosynthesis Chamaesyce Physiology symplastic Plant Science Biology phloem loading Photosynthesis 01 natural sciences Carbon Cycle 03 medical and health sciences food Euphorbia Phloem loading Water transport Ecology AcademicSubjects/SCI01210 Euphorbiaceae trees Plants Biological Evolution 030104 developmental biology Phenotype disjunct veins Trait Habit (biology) Tree (set theory) quantum yield 010606 plant biology & botany |
| Zdroj: | Journal of Experimental Botany |
| ISSN: | 1460-2431 0022-0957 |
| Popis: | We review possible physiological, anatomical, and evolutionary limitations that may explain the rarity of C4 photosynthesis in trees and discuss how the C4 trees in Euphorbia are exceptions to this. Since C4 photosynthesis was first discovered >50 years ago, researchers have sought to understand how this complex trait evolved from the ancestral C3 photosynthetic machinery on >60 occasions. Despite its repeated emergence across the plant kingdom, C4 photosynthesis is notably rare in trees, with true C4 trees only existing in Euphorbia. Here we consider aspects of the C4 trait that could limit but not preclude the evolution of a C4 tree, including reduced quantum yield, increased energetic demand, reduced adaptive plasticity, evolutionary constraints, and a new theory that the passive symplastic phloem loading mechanism observed in trees, combined with difficulties in maintaining sugar and water transport over a long pathlength, could make C4 photosynthesis largely incompatible with the tree lifeform. We conclude that the transition to a tree habit within C4 lineages as well as the emergence of C4 photosynthesis within pre-existing trees would both face a series of challenges that together explain the global rarity of C4 photosynthesis in trees. The C4 trees in Euphorbia are therefore exceptional in how they have circumvented every potential barrier to the rare C4 tree lifeform. |
| Databáze: | OpenAIRE |
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