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

In C plants, the enzymatic machinery underpinning photosynthesis can vary, with, for example, three distinct C acid decarboxylases being used to release CO in the vicinity of RuBisCO. For decades, these decarboxylases have been used to classify C species into three biochemical sub-types. However, more recently, the notion that C species mix and match C 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 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 species in the Paniceae enables the preliminary exploration of C sub-type evolution.