1. Evolution of Strigolactone Perception by Seeds of Parasitic Plants: Reinventing the Wheel 
Guosheng Xiong, Jiayang Li, Steven M. Smith 
Molecular Plant 
Volume 9, Issue 4, Pages (April 2016)
DOI: /j.molp
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2. Figure 1 Evolution of Strigolactone Receptors in Parasitic Plants.
Ancestral genes encoding the KAI2/HTL/D14L family underwent duplication with the emergence of seed plants to form genes encoding D14 (blue arrow), which is involved in SL perception during plant development, and the conserved KAI2 (KAI2c) protein branch (brown arrow) involved in seed germination (KAI2c). In root-parasitic plants, amplification and diversification of genes encoding KAI2 led to the formation of divergent (KAI2d) and intermediate (KAI2i) clades. The active site pocket of KAI2d proteins is predicted to be similar to that of the D14 protein and able to accommodate strigolactones such as strigol (shown). Substrates active on the KAI2i class are unclear, although karrikins and GR24 can be active, but the functions of these proteins are unclear. Proteins of the KAI2c group have smaller pockets, potentially able to accommodate karrikin-like compounds, as is the case with Arabidopsis KAI2/HTL. Thus, KAI2d proteins have apparently evolved from the KAI2c class to trigger Striga seed germination in response to SLs, instead of the ligands recognized by KAI2c. Images of protein binding pockets are from Conn et al. (2015).
Molecular Plant 2016 9, DOI: ( /j.molp )
Copyright © 2016 The Author Terms and Conditions