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Impact of immature fruit size and genotype on direct Caullogenesis in Monoembryonic-seed mango

Abul-Soad, A. A., Markhand, G. S., Solangi, N. D.
Acta horticulturae 2015 no.1083 pp. 85-94
2,4-D, activated carbon, antioxidants, callus, cultivars, culture media, explants, genotype, mangoes, micropropagation, nucellus, plantlets, rootstocks, seeds, shoots
The improved in vitro protocol of monoembryonic mango would facilitate the commercial micropropagation of cultivars and rootstocks. The nucellus tissue of mono-embryonic seeds of world-known mango cultivars ‘Saroli’, ‘Langra’ and ‘Chaunsa’ were used to induce the direct shoots. The simple procedure used for surface sterilization of the immature fruit resulted in 95% free-contaminants explants. The initial fruit size was found to be crucial for getting the DS within a short period of time (2 months). Full half of seeds from immature fruit without zygotic embryo were used as an initial explant. Browning of initial explants was controlled by anti-oxidants solution, activated charcoal containing-media and incubation in dark till maturation. The developed medium formula to induce cluster of shoots (0.5 cm long) was micro-salts of MS and macro of B5 supplemented with 4.52 μM 2,4-D and 9.83 μM 2iP within 3 months under dark. The appropriate fruit size used to induce the DS (caullogenesis) was 5-6 cm long. The smaller fruit size 1 cm long could not develop and died while the fruit size 2-4 cm long developed clusters of embryogenic callus under dark and 27±2°C. The induced clusters of shoots were cultured on the basal medium supplemented with 2.3 μM Kin and 0.49 μM 2iP in order to grow into small healthy plantlets under light and 27±2°C. Caullogenesis was detected only in ‘Langra’ and ‘Chaunsa’ whereas ‘Saroli’ explants failed throughout the two seasons’ experiment. The step-wise protocol and morphology of the induced DS were described in the current study.