Adventitous shoot regeneration from immature cotyledons of paper shelled almond cv. parbat

The main aim of this study is to regenerate almond cultivars indirectly through callus culture that will pave way for introduction of some novel genes like spring frost resistance genes (Transgenic almond) or development of somaclonal variants that can survive in fringed areas of temperate climate for expansive cultivation. In this regard indirect regeneration potential of four thin shelled almond cultivars: Parbhat, Shalimar, Waris and Mukhdoom of J and K India was studied. The source of explants were immature almonds collected 90-120 days after pollination from orchards. The proximal ends of the immature cotyledons after chemical sterilization were cultured on MS() medium. The cultures were then maintained at 25±3°C with 16 h photoperiod(3000 lux) both in presence as well as in absence of light for first 2 weeks of culture period. After 8 weeks of culture period the explants were examined for indirect shoot production. Morphogenetic callus and the shoots regenerated from the proximal ends of these cotyledons under the influence of different phytohormones. The effects of different concentrations of 6-benzylaminopurine (BAP), Indole 3 butyric acid (IBA) and Naphthalene acetic acid(NAA) in presence or absence of dark period were determined and the best results were obtained when abaxial cotyledon surface was in contact with the culture medium.Shoot regeneration percentage was highest in both cultivars with dark treatment on Murashige and Skoogs (MS) medium at BAP(20 µM) and IBA(5 µM) concentration. BAP(5 & 10 µM) and IBA(5µM) combination significantly reduced both shoot regeneration percentage and the number of adventitious shoots produced per explant. Without dark incubation for first 2 weeks of culture period regeneration percentage was decreased in both cultivars There was also significant decrease in regeneration potential of both the cultivars at IBA(10 µM) or NAA(5 & 10 µM) in combination with BAP(5,10 &20 µM).Frequency of shoot regeneration were 80% and 60% for cultivar Waris and Mukhdoom respectively.