Plant regeneration from nodal explants of ‘Irwin’ mango seedlings

Mango is the fifth most important fruit crop in the world in terms of production with an increasing demand for high-quality plant material for new plantings. Compared to other fruit tree crops, vegetative propagation in mango is slow and allows only a relatively limited production of plant material. To date, efficient procedures for in vitro establishment and micropropagation are not yet available in mango. This work aims at filling this gap. Germination of mango seeds in vitro, compared with ex vitro conditions, significantly increased the germination rate for the monoembryonic genotype tested (‘Irwin’). In vitro germination also increased the number of developed embryos for the two polyembryonic genotypes analysed, ‘Ataulfo’ and ‘Gomera-4’. Regarding the use of shoot tips for in vitro establishment and micropropagation, our results confirmed that this explant is not adequate for this purpose. We report for the first time the use of cotyledonary nodes as initial explants in mango. Axillary shoots were obtained in all the genotypes tested (‘Ataulfo’, ‘Sabre’, ‘Gomera-4’, ‘Irwin’ and ‘Keitt’), although the regeneration rate was highly genotype-dependent. Thidiazuron induced high-frequency regeneration patterns. The best results were observed with ‘Keitt’. When 3.0 mg l−1 thidiazuron was added to the medium, a 63.15% regeneration rate was reached and about 4 shoots per regenerating explant were obtained. Subsequently, microshoots excised from the cotyledonary nodes were successfully rooted in vitro and acclimatized to ex vitro conditions. Our results show that the use of cotyledonary nodes is efficient for mango mass propagation and, consequently, represents a qualitative advance for in vitro propagation of this recalcitrant species.

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