Optimizing Callus Induction and Plantlet Regeneration in Marigold Anther Culture: Effects of Pretreatments and Culture Conditions

Marigold (Tagetes spp.) holds significance in various industries, including pharmaceuticals, nutraceuticals, and pigments, due to its flower pigment and essential oil. Conventional breeding methods for genetic enhancement are time-consuming due to its cross-pollination nature. To expedite improvement, doubled haploid lines can be produced through androgenesis. In spite of the potential benefits, challenges such as genotype-specific responses, anther development stage, pretreatment and culture conditions pose significant hurdles. Addressing these factors could pave the way for more efficient application of androgenesis in marigold crop improvement, offering quicker pathways to developing superior plant varieties. This study aimed to determine the optimal temperature stress pretreatment, sucrose concentration in culture media and duration of darkness during anther incubation to enhance embryogenic callus proliferation and subsequent regeneration. It was found that subjecting marigold flower buds with anthers at the uninucleate stage to a temperature stress of 4 °C for 72 hours followed by culture in MS media containing 4% sucrose, supplemented with NAA (0.2 mg L-1), and BAP (1 mg L-1) yielded the best results. Ploidy analysis of fifty regenerated plantlets revealed varying ploidy levels, including haploid. These findings hold promise for advancing research on haploid and doubled haploid development in marigold and related species.