Improving the Efficiency of Adventitious Shoot Induction and Somatic Embryogenesis via Modification of WUSCHEL and LEAFY COTYLEDON 1.

Masaru Ohme-Takagi,Sumire Fujiwara,Nobutaka Mitsuda,Mikiya Takahashi,Miho Ikeda

doi:10.3390/plants9111434

Abstract

The induction of adventitious organs, such as calli, shoots, and somatic embryos, in tissue culture is a useful technique for plant propagation and genetic modification. In recent years, several genes have been reported to be adventitious organ inducers and proposed to be useful for industrial applications. Even though the Arabidopsis (Arabidopsis thaliana) WUSCHEL (WUS) and LEAFY COTYLEDON 1 (LEC1) genes can induce adventitious organ formation in Arabidopsis without phytohormone treatment, further improvement is desired. Here, we show that modifying the transcriptional repression/activation activities of WUS and LEC1 improves the efficiency of adventitious organ formation in Arabidopsis. Because WUS functions as a transcriptional repressor during the induction of adventitious organs, we fused it to an artificial strong repression domain, SUPERMAN REPRESSION DOMAIN X (SRDX). Conversely, we fused the strong transcriptional activation domain VP16 from herpes simplex virus to LEC1. Upon overexpression of the corresponding transgenes, we succeeded in improving the efficiency of adventitious organ induction. Our results show that the modification of transcriptional repression/activation activity offers an effective method to improve the efficiency of adventitious organ formation in plants.

Highlights

Induction of calli, adventitious shoots, and somatic embryos from somatic cells is important for plant propagation and transformation
A long hypocotyl, and a root meristem (Figure 1F), but the primary root meristem frequently formed additional shoots or somatic embryos (Figure 1G). This observation suggests that the root meristem is converted to a shoot or embryonic meristem in these transgenic lines
WUS induces ectopic stem cell identity [1,24], and somatic embryogenesis and shoot formation occur from roots of transgenic plants ectopically expressing WUS [1]

Summary

Introduction

Adventitious shoots, and somatic embryos from somatic cells is important for plant propagation and transformation. Plant somatic cells tend to have a high potential for regeneration via dedifferentiation and formation of adventitious shoots and somatic embryos under suitable tissue culture conditions, which are generally determined by light quality, temperature, and phytohormone concentrations. In many plant species, it is challenging to find suitable tissue culture conditions for plant regeneration from somatic cells. Various genes have been reported to be involved in adventitious organ formation processes, such as somatic embryogenesis and shoot and callus formation. WUSCHEL (WUS) and LEAFY COTYLEDON 1 (LEC1) are well documented for their role in somatic embryo induction [1,2]. WUS is a bifunctional homeodomain transcription factor that mainly acts as a repressor [3]

Objectives

Methods

Results

Conclusion