Finding the genes to build C4 rice

Rice, a C-3 crop, is a staple food for more than half of the world's population, with most consumers living in developing countries. Engineering C-4 photosynthetic traits into rice is increasingly suggested as a way to meet the 50% yield increase that is predicted to be needed by 2050. Advances in genome-wide deep-sequencing, gene discovery and genome editing platforms have brought the possibility of engineering a C-3 to C-4 conversion closer than ever before. Because C-4 plants have evolved independently multiple times from C-3 origins, it is probably that key genes and gene regulatory networks that regulate C-4 were recruited from C-3 ancestors. In the past five years there have been over 20 comparative transcriptomic studies published that aimed to identify these recruited C-4 genes and regulatory mechanisms. Here we present an overview of what we have learned so far and preview the efforts still needed to provide a practical blueprint for building C-4 rice.