WUSCHEL Overexpression Promotes Callogenesis and Somatic Embryogenesis in Medicago truncatula Gaertn

Abstract

The induction of plant somatic embryogenesis is often a limiting step for plant multiplication and genetic manipulation in numerous crops. It depends on multiple signaling developmental processes involving phytohormones and the induction of specific genes. The WUSCHEL gene (WUS) is required for the production of plant embryogenic stem cells. To explore a different approach to induce somatic embryogenesis, we have investigated the effect of the heterologous ArabidopsisWUS gene overexpression under the control of the jasmonate responsive vsp1 promoter on the morphogenic responses of Medicago truncatula explants. WUS expression in leaf explants increased callogenesis and embryogenesis in the absence of growth regulators. Similarly, WUS expression enhanced the embryogenic potential of hairy root fragments. The WUS gene represents thus a promising tool to develop plant growth regulator-free regeneration systems or to improve regeneration and transformation efficiency in recalcitrant crops.

Comparative Transcriptomics of Non-Embryogenic and Embryogenic Callus in Semi-Recalcitrant and Non-Recalcitrant Upland Cotton Lines

“…In other studies, LEC1 has been described as a central regulator, controlling different parts of embryo morphogenesis and photosynthesis as well as seed development [ 41 ]. WUS is a morphogenic regulator that has been shown to induce or stimulate cellular differentiation in a range of species, such as Arabidopsis [ 16 ], Zea mays [ 34 ], and Medicago [ 42 ]. In cotton, the WUS gene had little to no expression in either genotype and developmental stage, suggesting that other genes have a more primary role in stimulating the transition from NEC to EC cells.…”

miR394 enhances WUSCHEL‐induced somatic embryogenesis in Arabidopsis thaliana

“…Therefore, we used L er as a model genotype for SE recalcitrance and sought for ways to overcome this block. Previous studies had shown that expression of the transcription factor WUS enhances SE formation in several species (Arroyo‐Herrera et al ., 2008; Bouchabké‐Coussa et al ., 2013; Xiao et al ., 2018; Kadri et al ., 2021; Lou et al ., 2022). In the shoot meristem, WUS acts with miR394 to maintain stem cells in a yet unknown complex genetic and ecotype‐dependent manner (Knauer et al ., 2013).…”

MtCLE08, MtCLE16, and MtCLE18 Transcription Patterns and Their Possible Functions in the Embryogenic Calli of Medicago truncatula

“…Transcription factors from the WOX family regulate cell proliferation and differentiation, and different WOX genes have been found to stimulate regeneration processes. For example, WUS or its orthologs have been shown to induce regeneration in many plant species and can be applied as morphogenic regulators to speed up the transformation process or to make it possible [ 22 , 23 ]. WOX2 and 8 induce regeneration in tobacco [ 24 ], and MtWOX9-1 has been shown to stimulate SE in M. truncatula [ 15 ].…”