Meagher Laboratory

There are four ancient subclasses of actin depolymerizing factor (ADF/cofilin) genes that predate the separation of monocots and dicots from a common ancestor. In Arabidopsis there are 11 ADF genes as shown in this ADF protein sequence tree (Ruzicka et al., 2007)

 

Subclass I ADFs (ADF1 to 4, adjacent figure)were expressed strongly and constitutively in all vegetative and reproductive tissues except pollen. 

Subclass II ADFs (ADF7, 8, 10, 11) were expressed specifically in mature pollen and pollen tubes or root epidermal trichoblast cells and root hairs, and thesepatterns evolved from an ancientdual expression pattern comprised of bothpolar tip-growth cell-types, still observed in the monocot Oryza sativa. 

Subclass III ADFs (ADF5 & 9) were expressed weakly in vegetative tissues, but were strongest in fast growing, and/or differentiating cells including callus, emerging leaves, and meristem regions. 

The single Subclass IV ADF6 was constitutively expressed at moderate levels in all tissues including pollen. 

 

Figure Legend. Phylogeny of Arabidopsis ADFs

Neighbor-joining protein sequence phylogeny showing all eleven ADF proteins from Arabidopsis (At), and representatives from rice (Os) and poplar (Pt). Bootstrap values are shown on the branch points of the tree. 

Subclasses I to IV indicated by vertical bars at right.  Subclass II was further separated into subclasses IIa and IIb. 

Analysis was rooted using the Chlamydomonasreinhardtii Chlre3ADF1 sequence.  Arabidopsis ADF protein sequences and gene designations:  ADF1 (At3g46010), ADF2 (At3g46000), ADF3 (At5g59880), ADF4 (At5g59890), ADF5 (At2g16700), ADF6 (At2g31200), ADF7 (At4g25590), ADF8 (At4g00680), ADF9 (At4g34970), ADF10 (At5g52360), and ADF11 (At1g01750); Oryza sativa ADF protein sequences and gene designations:  ADF7 (Os05g02250), ADF1 (Os02g44470), ADF6 (Os04g46910), ADF5 (Os03g13950), ADF2 (Os03g56790); Populus trichocarpa ADF protein sequences and desginations: ADF5 (ID number Pt720178), ADF10 (Pt570479), ADF9 (Pt88969), ADF8 (Pt554345), ADF13 (Pt648773), ADF16 (Pt685386); and Chlamydomonas reinhardtii ADF1 Protein ID 26103.