Evolution

Minor veins are key to photosynthesis

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Science  25 Jan 2019:
Vol. 363, Issue 6425, pp. 361-362
DOI: 10.1126/science.363.6425.361-b

Carbon fixation via C4 photosynthesis allows plants to tolerate drought, high temperatures, and nitrogen and carbon dioxide limitations. In plants, the C4 pathway has evolved from the ancestral C3 pathway multiple times. To identify developmental changes that accompanied the transition between photosynthetic types, Lundgren et al. investigated leaf anatomy in Alloteropsis semialata. Individuals of this grass species can photosynthesize by either or both pathways. The ratio of mesophyll to bundle sheath tissue, as determined by the number of minor veins, correlates with the photosynthetic route used by a plant. Growth under controlled conditions indicated that the presence of minor veins is not a plastic response to the environment. Instead, developmental variation in A. semialata leaf cell type directs the type of carbon fixation.

Ecol. Lett. 22, 302 (2019).

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