Induction of polyploidy in citrus scions through in vitro colchicine treatment of seed-derived explants

V. Narukulla, Y. Lahane, S. Pandey, K. Fiske
Tetraploid plants are essential for interploid hybridization to create triploidy for seedless citrus. Here we report an efficient method for generating auto tetraploidy in ‘Nagpur mandarin’, ‘Kinnow’ mandarin, sweet orange and pummelo cultivars. Autotetraploids were developed by treating seed derived explants with colchicine concentrations of 0.1, 0.2, 0.3% and control for durations of 16 and 24 h. Seed derived explants were obtained by culturing sterile seed on MS basal media. 5-8 mm size seedlings were exposed to colchicine treatment. After treatment, survived seedlings were minigrafted on five-month-old rootstock for better growth. Emerging shoot leaves were analysed for ploidy via flow cytometry and cytological method. The most efficient colchicine concentration was 0.1% for 24 h, demonstrated highest tetraploid induction percentage (15.22%) in ‘Nagpur mandarin’ wherein ‘Kinnow’ genotype had poor response for induction of tetraploids. Experimental result shows that the higher colchicine concentration and longer exposure hampered the seedling growth causing browning, necrosis in the meristematic tissues. Highest colchicine concentrations (0.3%) was lethal for all cultivars and seedlings survived at this concentration induced higher ploidy level like hexaploid, heptaploid. Reversion of the mixoploids(2n+4n) into diploids was also observed in the field evaluation trial. Flow cytometry and cytological method demonstrated autotetraploid conformation in analysed samples. Recovered autotetraploid plants were identified with morphological variables such as higher stomata size, lower stomata density, leaf area, short internode and flower with thickened petals compared to diploid control plants.
Narukulla, V., Lahane, Y., Pandey, S. and Fiske, K. (2024). Induction of polyploidy in citrus scions through in vitro colchicine treatment of seed-derived explants. Acta Hortic. 1399, 39-50
DOI: 10.17660/ActaHortic.2024.1399.5
https://doi.org/10.17660/ActaHortic.2024.1399.5
citrus, seed, auto tetraploid colchicine, flow cytometry, cytogenetic test
English
1399_5
39-50

Acta Horticulturae