Background:

Cosmos atrosanguineus (Asteraceae) is a perennial herbaceous plant with tuberous rhizomes endemic to Mexico. It is sterile and does not produce seeds, requiring alternative propagation methods.

Questions:

Can in vitro techniques be used to develop microrhizomes and microtubers as propagules for Cosmos atrosanguineus?

Studied species:

The study focused on C. atrosanguineus explants cultured under controlled in vitro conditions, with emphasis on rhizome and tuber development.

Study site:

Experiments were conducted in vitro under laboratory conditions.

Methods:

Culture media were supplemented with auxins, particularly 1-Naphthaleneacetic Acid (NAA), and with varying concentrations of sucrose. Morphological, anatomical, and biochemical analyses were performed to confirm tuberization. Additionally, transpiration rates were compared between acclimatized plantlets and those regenerated from in vitro microrhizomes.

Results:

Supplementation with 1 mg/L NAA promoted microrhizome development, while 12 % sucrose stimulated microtuber induction. Anatomical characterization of tuberized microrhizomes confirmed their similarity to the naturally tuberizing species Cosmos pringlei. Plantlets derived from microrhizomes successfully acclimatized ex vitro, showing functional transpiration.

Conclusions:

The in vitro generation of microrhizomes and microtubers represents a viable propagation strategy for C. atrosanguineus. These propagules are suitable for ex vitro establishment, offering an effective alternative for conserving and propagating this endemic sterile species.

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