The 'stemness' trait in recalcitrant seeds of Garcinia xanthochymus is modulated by hormonal balance

Wen, Bin

PLANT GROWTH REGULATION

2026

106

1

Wen, B; Chen, LG

Garcinia seeds have an unusual seedling regeneration trait involving Garcinia-type germination and totipotent germinability, i.e., 'stemness'. These regeneration traits are regarded as an adaptation to animal predation; however, their cellular, physiological and hormonal bases are largely unexplored. We used Garcinia xanthochymus seeds to investigate the morphological, cytological and metabolomic basis of seeds and seed fragments using diverse methods. Irrespective of the orientation of the seeds or seed segments on sowing, the shoot always emerged from the proximal region and primary root from the distal end. Likewise, no matter how the explants were inoculated in vitro, shoots emerged only from the proximal edge of the seed slices. These regeneration patterns indicated that the Garcinia xanthochymus 'stemness' trait has a clear root-shoot polarity even though the seed lacks clearly differentiated components of axis and cotyledon, based on our morphological and cytological investigations. The seeds contain diverse and abundant plant growth regulators, especially auxins, cytokinins and GAs, and these hormones exhibit concentration gradients across the distal, middle and proximal parts of the seeds. The whole seeds are composed of living cells with active metabolism, as indicated by the TTC test, and callus could grow over all cut surfaces (distal-, proximal-, transversely-, longitudinally-, horizontally-cut) except those in contact with the medium when incubated on MS medium without exogenous hormones. These results suggest that much of the 'seed' tissue has endogenous hormone levels sufficient for cell division and morphogenesis, enabling seeds to exhibit totipotency in response to physical damage.