In Vitro Culture Initiation and Micropropagation Optimization of Plantago Halophytes: A Sustainable Approach to Exploring Valuable Plant Species

Halophytes are salt-tolerant plants with ethnomedicinal value and growing potential in food and cosmetics; their adaptability to extreme conditions makes them promising candidates for sustainable agriculture and crop development in salt-affected areas. In vitro plant tissue culture further supports this by enabling resilient plant production in the face of climate and food security challenges. In this study, in vitro cultures of two medicinal halophytes from the genus Plantago (P. coronopus and P. crassifolia) were established to optimize their micropropagation protocol. Seed germination percentages, growth parameters, micropropagation rates, rooting efficiency, and physiological condition were evaluated. Growth media (modified MS medium) differed in the type of cytokinin. The seed germination efficiency was monitored at weekly intervals for 8 weeks, and other growth parameters were evaluated in 6- and 12-week cultures. Differences in both the rate and efficiency of in vitro germination between the two species were observed, with approximately 73% germination reached by P. coronopus and 47% by P. crassifolia after 4 weeks, and 80% and 53% after 8 weeks, respectively. The addition of 0.5 mg dm−3 kinetin plus 0.5 mg dm−3 IAA (indole acetic acid) proved to be effective in promoting growth in P. coronopus, resulting in longer plantlets and higher multiplication rates, while the addition of meta-topolin (mT) was a better stimulator of shoot and root growth in P. crassifolia. The highest multiplication coefficient, 6.22 for P. coronopus and 4.90 for P. crassifolia, was obtained on the P1 medium for both species. Importantly, medium with mT also had a stimulating effect on rooting in both species over the long term (12-week culture). The developed PTC enables efficient propagation and trait selection in halophytes, supporting sustainable large-scale production of the studied Plantago species, and facilitating future research on salt stress tolerance.