Organogenesis dan Mutasi Induksi Marigold Tagetes erecta dan Tagetes patula dengan Kolcisin secara in vitro

Abstract

Marigold (Tagetes sp.) is a popular annual flowering plant widely cultivated in many countries, including Indonesia. This plant has high economic value, particularly in Bali and Central Java, as an ornamental flower, religious ceremony material, cosmetic raw material, medicine, insect repellent, and pathogen inhibitor. Varieties of marigold with unique colors such as white or dark red, are still rare in Indonesia. Induced mutation using colchicine has become important for increasing genetic diversity, particularly in obtaining flower color and size variations. Additionally, using growth hormones such as thidiazuron (TDZ) has proven. effective in stimulating plant growth and development, including in vitro propagation. This study aims to determine the optimal medium for organogenesis induction, the effect of colchicine concentration on callus induction and organogenesis, and to obtain the LC50 value for marigold callus. It also seeks to obtain putative mutants of Tagetes erecta cv. Sudamala Orange 1 and Tagetes patula cv. Sudamala Barak in vitro. This study utilized two plant genotypes: Tagetes erecta cv. Sudamala Oranye 1 and Tagetes patula cv. Sudamala Barak. The first experiment involved callus induction and plant regeneration using thidiazuron. The experiments were conducted from January to June 2023 at Tissue Culture Laboratory 1, Department of Agronomy and Horticulture, Faculty of Agriculture, Bogor Agricultural University. The results showed that the best callus induction and shoot regeneration medium in Sudamala Oranye 1 was MS0 + IAA 0.5 ppm + BAP 7 ppm + TDZ 0.50 ppm. In comparison, for Sudamala Barak it was MS0 + IAA 0.5 ppm + BAP 7 ppm + TDZ 1.00 ppm. The number of shoots on Sudamala Orange in the best medium was 2.3 shoots, while on Sudamala Barak was 0,9 shoots. The second experiment was a colchicine-induced mutation on organogenic callus. This experiment was conducted from August to October 2024 at the Tissue Culture Laboratory 1, Department of Agronomy and Horticulture, Faculty of Agriculture, Bogor Agricultural University. The callus was treated with colchicine two weeks after planting. The results showed that increasing colchicine concentration up to (0.030%) inhibited callus growth in marigold plants. The LC50 values were 0.016% for Sudamala Orange 1 and 0.022% for Sudamala Barak. Colchicine-induced mutation produced 7 putative mutant planlets (MV1) of Sudamala Orange 1 and 4 putative mutant planlets of Sudamala Barak. Observed variables such as stomatal length, stomatal density, and chloroplast number can be used as indicators of ploidy levels in marigold plants. The putative mutant plant labeled SB.0.275.MV4.11 exhibited the lowest stomatal count with 8.7 stomata, stomatal length of 129.3 µm, stomatal density of 7 µm mm-2 and 24 chloroplasts. Correlation analysis revealed a positive correlation between stomatal size and chloroplast number, indicating that ploidy level serves as an early marker for determining ploidy status in putative mutant marigold plants