Effects of explant type, growth regulators and light intensity on callus induction and plant regeneration in four ecotypes of Persian shallot (Allium hirtifolium)

- A successful protocol for callus induction and plant regeneration from Allium hirtifolium is described.
- Basal plate was the best explant for callus induction in Allium hirtifolium..
- 2,4-D not only induced callus initiation but also maintained callus proliferation.
- Shoot regeneration from callus was variable in response to different cytokinins.
- The regenerated shoots in growth regulator free-medium were albino.
- Shoot regeneration significantly influenced by light intensity.

To establish an efficient protocol for shoot regeneration from callus, the effects of explant type, growth regulators and ecotypes on callus induction of Persian shallot (Allium hirtifolium) were evaluated. The results showed that basal plate was the best explant for callus induction when cultured on medium supplemented with 1.5 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg l−1 6-benzylaminopurine (BAP). The highest callus growth index (69.04%) was achieved on medium with 1.5 mg l−1 2,4-D in Zanjan ecotype. In second experiment the effects of different cytokinines, light intensity and ecotypes on shoot regeneration of A. hirtifolium callus were investigated. The proliferated calli were transferred to MS medium supplemented with different cytokinins (6-benzylaminopurine, kinetin and thidiazuron) in combination with 1-naphthaleneacetic acid (NAA) to investigate their potential for shoot induction. Shoots regenerated at the highest frequency when calli were cultured on medium with 1 mg l−1 TDZ and 0.5 mg l−1 NAA in almost all ecotypes. Shoot regeneration significantly influenced by light intensity and the greatest of shoot induction (77.58%) and number of shoots per callus (16.94) were achieved under a light intensity of 60 μmol m−2 s−1. This optimized protocol will be useful for any future breeding improvement programs of Persian shallot using biotechnological means.

The proliferated A. hirtifoilum calli exhibited morphological variation and two types of calli were observed: Type I calli were compact and yellowish and type II calli were friable, globular, white.156