GhWOX11 and GhWOX12 promote cell fate specification during embryogenesis

Abstract

The acquisition of transgenic materials relies on an efficient genetic transformation system, in which WUSCHEL-related homeobox genes play imperative roles in enhancing somatic embryogenesis potential. In our study, we isolated and characterized the cotton (Gossypium hirsutum L) homologues of Arabidopsis WOX11 and WOX12, namely GhWOX11_At, GhWOX11_Dt, GhWOX12_Dt and GhWOX12_At. Domain analysis indicated that the putative GhWOX11 and GhWOX12 proteins contain a highly conserved DNA-binding HOX domain or ACR domain. We have also demonstrated that callus initiation and adventitious root formation are simultaneously regulated by GhWOX11/12 genes. The asymmetric distribution of auxin leads to the differential expression of GhWOX11 and GhWOX12, which controls the formation of callus and presents a polar distribution at the ends of hypocotyl. Furthermore, overexpression of GhWOX11/12 significantly promotes the formation of callus and the fate transition from callus cell to pluripotent cell in G. hirsutum. On the other hand, expression of the chimeric GhWOX11/12 repressor in cotton callus inhibited embryogenic callus formation. Overexpression of GhWOX11 also promoted the formations of green callus, adventitious roots and adventitious shoots in Arabidopsis, corroborating its conserved functional role in inducing plant somatic embryogenesis and root development. Our results show that GhWOX11 and GhWOX12 genes play an important role in the process of cell fate transition in the early stage of somatic embryogenesis, providing a new perspective for the optimization of plant transformation systems.