1. by Jacob O. Brunkard, Anne M. Runkel, and Patricia C. Zambryski
Comment on “A promiscuous intermediate underlies the evolution of LEAFY DNA binding specificity”
by Jacob O. Brunkard, Anne M. Runkel, and Patricia C. Zambryski
Science
Volume 347(6222):
February 6, 2015
Published by AAAS

2. Fig. 1 The LEAFY gene tree within the constraints of plant evolution
Fig. 1 The LEAFY gene tree within the constraints of plant evolution.(A) Although not their preferred model, Sayou et al. provide a scenario of LFY evolution that considers the evolutionary history of plants (reproduced here).
The LEAFY gene tree within the constraints of plant evolution.(A) Although not their preferred model, Sayou et al. provide a scenario of LFY evolution that considers the evolutionary history of plants (reproduced here). This phylogeny assumes that the promiscuous LFY form found in hornworts is “intermediate,” evolving after the divergence of algae, and then that new forms evolved separately in liverworts and mosses, were retained in hornworts, and evolved again in land plants. This model requires three changes in LFY binding specificity as well as convergent evolution of type I binding specificities in liverworts and polysporangiophytes. (B) We show that the most parsimonious explanation for LFY evolution is that type I binding arose in the early ancestors of land plants, and then new binding specificities evolved in mosses and hornworts. DNA binding specificity is color-coded: type III (blue), promiscuous (red), type II (green), type I (orange). Each change in binding site specificity is numbered.
Jacob O. Brunkard et al. Science 2015;347:621
Published by AAAS

3. Fig. 2 Revised hypothesis of LEAFY evolution
Fig. 2 Revised hypothesis of LEAFY evolution.(A) Alignment of predicted LEAFY amino acid sequences representing each clade of land plants.
Revised hypothesis of LEAFY evolution.(A) Alignment of predicted LEAFY amino acid sequences representing each clade of land plants. Key residues 312 (blue), 345 (magenta), and 387 (yellow) confer distinct DNA binding specificities. P. commune gametophytes express three paralogs of LEAFY, two with type II binding specificity (D312-C345-H387) and one with type I binding specificity (H312-R345-H387). (B) Constrained by the accepted evolutionary history of plants, LEAFY most likely evolved type I binding site specificity (yellow) in the ancestor of all land plants, later gaining new binding site specificities (type II, green) in mosses (through gene duplication) and in hornworts (“promiscuous” type, red) by an unknown mechanism, but likely through gene duplication as well. Tree follows the style of figure 4 in (2).
Jacob O. Brunkard et al. Science 2015;347:621
Published by AAAS