Simple changes underpin the evolution of a complex trait

Professor Julian Hibberd’s Lab published a significant step towards understanding the efficient form of photosynthesis known as the C₄ pathway in The Plant Cell on the 15^th of January 2016. In most photosynthetic organisms, ranging from bacteria to land plants, the first step of photosynthesis is catalysed by the enzyme RuBisCO. However, under warm, dry conditions the efficiency of Rubisco is reduced, which can lead to lower crop yields. Some plants have evolved adaptations to overcome this problem, one of which is known as the C₄ photosynthetic pathway, adoption of which allowed fast-growing species such as switchgrass to dominate savannahs and prairies. As C₄ photosynthesis requires the co-ordinated action of many genes, Williams and Burgess et al. sought to identify C₄ genes that are expressed in mesophyll cells and regulated by the same regulatory elements. Starting with a gene encoding carbonic anhydrase from the C₄ species Gynandropsis gynandra they established that its regulation was mediated by a short sequence in the untranslated part of the gene. Furthermore, this sequence was found in additional C₄ genes as well as orthologous genes from C₃ species, and in each case, regulation appears to act on the translation of RNA to protein. The work provides evidence that the complex C₄ trait is underpinned by the repeated use of simple sequence motifs.

Williams BP, Burgess SJ, Reyna-Llorens I, Knerova J, Aubry S, Stanley S, Hibberd JM. (2016) An untranslated cis-element regulates the accumulation of multiple C4 enzymes in Gynandropsis gynandra mesophyll cells. The Plant Cell.