Deakin University
Browse
malerba-cellsizephotosynthesis-2018.pdf (1.78 MB)

Cell size, photosynthesis and the package effect: an artificial selection approach

Download (1.78 MB)
journal contribution
posted on 2018-07-01, 00:00 authored by Martino MalerbaMartino Malerba, M M Palacios, Y M Palacios Delgado, J Beardall, D J Marshall
Cell size correlates with most traits among phytoplankton species. Theory predicts that larger cells should show poorer photosynthetic performance, perhaps due to reduced intracellular self-shading (i.e. package effect). Yet current theory relies heavily on interspecific correlational approaches and causal relationships between size and photosynthetic machinery have remained untested. As a more direct test, we applied 250 generations of artificial selection (c. 20 months) to evolve the green microalga Dunaliella teriolecta (Chlorophyta) toward different mean cell sizes, while monitoring all major photosynthetic parameters. Evolving larger sizes (> 1500% difference in volume) resulted in reduced oxygen production per chlorophyll molecule – as predicted by the package effect. However, large-evolved cells showed substantially higher rates of oxygen production – a finding unanticipated by current theory. In addition, volume-specific photosynthetic pigments increased with size (Chla+b), while photo-protectant pigments decreased (β-carotene). Finally, larger cells displayed higher growth performances and Fv/Fm, steeper slopes of rapid light curves (α) and smaller light-harvesting antennae (σPSII) with higher connectivity (ρ). Overall, evolving a common ancestor into different sizes showed that the photosynthetic characteristics of a species coevolves with cell volume. Moreover, our experiment revealed a trade-off between chlorophyll-specific (decreasing with size) and volume-specific (increasing with size) oxygen production in a cell.

History

Journal

New phytologist

Volume

219

Issue

1

Pagination

449 - 461

Publisher

Wiley

Location

Chichester, Eng.

ISSN

0028-646X

eISSN

1469-8137

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal