检索历史 清除

Plant cells possess the unique ability to revert differentiated so-matic cells back to a pluripotent state,a trait utilized in in vitro tissue culture.This plant propagation strategy involves the exogenous supplementation of auxin and cytokinin,two phytohor-mones that promote cellular reprogramming and de novo organo-genesis.When exposed to an auxin-rich medium,somatic cells proliferate and form the callus,a pluripotent cell mass.Following the attainment of pluripotency,the callus can be transferred to a cytokinin-rich medium to induce shoot regeneration.Studies with the model plant Arabidopsis thaliana have revealed that pluripo-tency is attained in a specific group of cells located in the middle cell layer of the callus exhibiting a transcriptional profile similar to the root meristem's quiescent center.Within this cell cluster,the root stem cell regulators WUSCHEL-RELATED HOMEOBOX5 and-7 interact with PLETHORA 1(PLT1)and PLT2 to stimulate local auxin production and establish a hormone gradient(Zhai and Xu,2021).In addition,WUSCHEL-RELATED HOMEOBOX5 and-7 increase sensitivity to cytokinin by suppressing type A ARABIDOPSIS RESPONSE REGULATORs through direct interac-tion with type B ARABIDOPSIS RESPONSE REGULATORs(Zhai and Xu,2021).This process promotes the expression of WUSCHEL,a master regulator of shoot stem cell specification in the callus(Zhang et al.,2017).