What is the "GMC-auxin intermediate state"?

In the research published by the team from Shandong Agricultural University in the journal Cell, a core concept runs through the entire study - "GMC-auxin intermediate state" (Guard Mother Cell - Auxin Intermediate State). This is a crucial transitional state for plant cells during their "transformation" process. In the words of the team, this is the "fork in the road" of cell fate.

The "Guard Mother Cell" (GMC) in the leaf epidermis will differentiate into stomata-tiny holes used by plants for respiration and transpiration. But when certain conditions trigger, these cells will "turn" at this junction and go the other way: into totipotent stem cells, and eventually develop into embryos.

Cells"

Research team used advanced single-cell sequencing, microdissection transcriptome sequencing, and in vivo imaging to document the complete path of cell fate remodeling, revealing two key directions:

Path one (normal development): stomatal precursor cells continue to differentiate into stomata. This is the "job" of the cell ".

Path two (reprogramming): driven by a large number of endogenous auxin synthesis, a single somatic cell is reprogrammed into a totipotent stem cell and embarked on the road of embryonic development.

Researchers found that the key factor that determines which way a cell goes is the level of endogenous auxin synthesis in the cell.

GMC-auxin

In GMC-auxin intermediate state, what changes have taken place in the cell?

1. Chromatin remodeling

Cells undergo deep chromatin remodeling. In layman's terms, the cell's "genome library" is reorganized-genes that were originally turned off are turned on, and genes that were originally active may be turned off. A large number of previously silenced genes are gradually activated.

2. Epigenetic reprogramming

Inhibition of cellular reprogramming is epigenetic modification, especially H3K27me3 this inhibitory histone modification. In the early stage of somatic embryogenesis, LEC2 can not only activate gene expression as a transcription factor, but also regulate the expression of pluripotency genes through epigenetic remodeling.

3. Positive feedback loop of auxin

Study found that exogenous auxin can activate the synthesis of endogenous auxin through the LEC2 gene, forming a positive feedback loop of "auxin-LEC2-auxin. This is the key to plant cell reprogramming.

As Professor Zhang Xiansheng said, simply adding exogenous hormones cannot replace the auxin synthesized by cells-only the auxin produced by the cells themselves can truly trigger the opening of pluripotency.

Intermediate state?

"Cell" magazine believes that the GMC-auxin intermediate state revealed by the study is an "exciting breakthrough" and defines the molecular path of stomatal precursor cells to pluripotent stem cells for the first time.

The novelty of this discovery lies in:

1. For the first time, the cell type of origin of plant totipotent stem cells-not arbitrary somatic cells, but "stomatal precursor cells" with specific identities-was clarified ";

2. Defining the key node of cell fate transition-GMC-auxin intermediate state;

3. Reveals the central role of auxin as a "fate switch.

Zhong Kang, an academician of the Chinese Academy of Sciences, pointed out that the study proved that plant regeneration can be directly triggered by specific lineage cells, rather than relying solely on the dedifferentiation process, providing a theoretical blueprint for the optimization of crop regeneration system.

Said, "In the future, it may be possible to achieve 'rapid cloning' of fine crop varieties through precise regulation of cell totipotency, greatly shorten the breeding cycle and serve precise design breeding. This will also inject new impetus into the efficient protection of rare plant germplasm resources and plant synthetic biology."

References:

1. Tang, L., et al. Time-resolved reprogramming of single somatic cells into totipotent states during plant regeneration. Cell, 2025. DOI: 10.1016/j.cell. 2025.08.031

2. Review article: From single somatic cell to totipotent embryo: the reprogramming journey of cell fate