Developmental regulatory genes: Key switches in the developmental events of plant tissue culture

Plant tissue culture (PTC) is a well-practiced biological approach in industrial application, as well as basic and applied research for plantlet regeneration. Organogenesis of callus, somatic embryos, shoot, root, and plantlet regeneration are common techniques. Plant tissue culturists use external plant growth regulators (PGRs), different kinds of light, and other modifications for efficacious in vitro organogenesis. Any modification of the culture environment can trigger the expression of many genes in organogenesis and regeneration processes. Developmental regulatory genes such as WUSCHEL ( WUS ), WUSCHEL-RELATED HOMEOBOX ( WOX ), LEAFY COTYLEDON ( LEC ), BABY BOOM ( BBM ), SOMATIC EMBROYOGENESIS RECEPTOR KINASE ( SERK ), GROWTH REGULATING FACTORS ( GRF ), and WOUND INDUCED DEDIFFERENTIATION1 ( WIND1 ) are some of the key genes that actively involved in the in vitro organogenesis and plantlet regeneration process. Ectopic expression of WUS , WOX , LEC , BBM , and GRF acted differently, but overexpression of these genes can increase the plant transformation efficiency. In vitro organogenesis processes alter epigenetic marks, especially DNA methylation and histone modifications independently or by the modification of any factors in PTC. Alteration of epigenetic marks can regulate the transcription of genes leading to the promotion or demotion of the in vitro organogenesis process. It is possible to get calli, somatic embryos, shoots, roots, and plantlets without any assistance from PGRs by overexpressing developmental regulatory genes in plant tissue culture. In this review, we summarized the connection between gene expressions and their regulation at developmental events in PTC.