Commentary: New evidence for grain specific C4 photosynthesis in wheat.

Abstract

Analysis of the transcriptome revealed the expression of a complete set of enzymes specific for a C4 photosynthetic pathway in the pericarp of the developing wheat seed (Rangan et al., 2016). C4 photosynthesis is not utilized in wheat leaves with temperatures during the early vegetative stages of wheat growth favoring C3 photosynthesis. Wheat crops mature in the spring when growing in the native “Mediterranean” climate of wild wheat progenitors and face rapidly increasing temperatures and drying conditions. The activity of the C4 pathway may contribute to crop yields especially in wheat crops under temperature or moisture stress during grain filling. The anatomy of the seed supports photosynthesis with cross cells and tube cells in what we are calling “Bose” anatomy paralleling the “Kranz” anatomy of C4 leaves with mesophyll cells and bundle sheath cells. Photosynthesis (C4) in these tissues may make a significant contribution to grain yield through efficient carbon capture. C4 photosynthesis in the wheat seed provides an adaptation to heat and moisture stress and is an efficient mechanism for minimizing carbon loss due to respiration during grain filling through re-fixation of carbon