Recently, the research entitled “GhRCD1 regulates cotton somatic embryogenesis by modulating the GhMYC3-GhMYB44-GhLBD18 transcriptional cascade” has been published by New Phytologist. In this paper, researchers from the Institute of Cotton Research (CCRI)　report that cotton RADICAL-INDUCED CELL DEATH1 (GhRCD1)interacts with　Myelocytomatosis transcription factorGhMYC3, which is constituted as a tetrapartite module consisting of GhRCD1-GhMYC3-GhMYB44-GhLBD18,thus ensuring the sequential cell fate transition during the somatic embryogenesis (SE).This study sheds important new light on the totipotency and pluripotency acquisition of cotton somatic cells.

Plant SE is a multifactorial developmental process where embryos that can develop into whole plants are produced from somatic cells rather than through the fusion of gametes. The molecular regulation of plant SE, which involves the fate transition of somatic cells into embryogenic cells (ECs), is intriguing yet remains elusive. In this study, we deciphered the molecular mechanisms by which GhRCD1 interacted with GhMYC3 to regulate cell fate transitions during SE in cotton. Two GhMYC3 downstream SE regulators, GhMYB44 and GhLBD18, were identified. On top of the regulatory cascade, GhRCD1 antagonistically interacted with GhMYC3 to inhibit the transcriptional function of GhMYC3 on GhMYB44 andGhLBD18. Interestingly,  GhRCD1 ,  GhMYC3 ,  GhMYB44 , and  GhLBD18  showed a temporal expression pattern during callus induction, proliferation, and embryogenic callus acquirement processes,　and regulated the dynamic accumulation of reactive oxygen species (ROS). Our findings elucidated that SE homeostasis was maintained by the tetrapartite module,GhRCD1–GhMYC3–GhMYB44–GhLBD18,which temporally modulated the accumulation of intracellular ROS and sequentially regulated SE homeostasis.

This study was funded by the National Natural Science Foundation of China (31621005, 31701476 and 32171996), theNational Key R&D Program of China (2022YFF1001400) and Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences,and the China Agriculture Research System of MOF and MARA (CARS-15-02). Researchers Fuguang Li and Xiaoyang Ge from CCRI are the co-corresponding authors, doctoral students Jiachen Yuan, Hang Zhao, Ye Wang, Peng Wang and master student Xingxing Liu are the co-first authors.

The article can be found: https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.19120

Fig 1. A proposed model for GhRCD1-GhMYC3-GhMYB44-GhLBD18 signaling cascade-regulated somatic embryogenesis.

By Xiaoyang Ge (gexiayang@caas.cn)