Distinct C 4 sub-types and C 3 bundle sheath isolation in the Paniceae grasses.

In C 4 plants, the enzymatic machinery underpinning photosynthesis can vary, with, for example, three distinct C 4 acid decarboxylases being used to release CO 2 in the vicinity of RuBisCO. For decades, these decarboxylases have been used to classify C 4 species into three biochemical sub-types. However, more recently, the notion that C 4 species mix and match C 4 acid decarboxylases has increased in popularity, and as a consequence, the validity of specific biochemical sub-types has been questioned. Using five species from the grass tribe Paniceae, we show that, although in some species transcripts and enzymes involved in multiple C 4 acid decarboxylases accumulate, in others, transcript abundance and enzyme activity is almost entirely from one decarboxylase. In addition, the development of a bundle sheath isolation procedure for a close C 3 species in the Paniceae enables the preliminary exploration of C 4 sub-type evolution.