Decoding the gene coexpression network underlying the ability of Gevuina avellana to live in diverse light conditions.

ABSTRACT

Gevuina avellana (Proteaceae) is a typical tree from the South American temperate rainforest. Although this species mostly regenerates in shaded understories, it exhibits an exceptional ecological breadth, being able to live under a wide range of light conditions. Here we studied the genetic basis that underlies physiological acclimation of the photosynthetic responses of G. avellana under contrasting light conditions. We analyzed carbon assimilation and light energy used for photochemical processes in plants acclimated to contrasting light conditions. Also, we used a transcriptional profile of leaf primordia from G. avellana saplings growing under different light environments in their natural habitat, to identify the gene coexpression network underpinning photosynthetic performance and light-related processes. The photosynthetic parameters revealed optimal performance regardless of light conditions. Strikingly, the mechanism involved in dissipation of excess light energy showed no significant differences between high- and low-light-acclimated plants. The gene coexpression network defined a community structure consistent with the photochemical responses, including genes involved mainly in assembly and functioning of photosystems, photoprotection, and retrograde signaling. This ecophysiological genomics approach improves our understanding of the intraspecific variability that allows G. avellana to have optimal photochemical and photoprotective mechanisms in the diverse light habitats it encounters in nature.