Since the first report of induction of androgenesis in Datura (Guha and Maheshwari, 1964), anther culture has gained considerable importance in our efforts to produce haploids and dihaploids. Haploid plantlets are formed in two distinct ways: by embryos originating directly from microspores without callusing (direct androgenesis) or by organogenesis from haploid callus tissue. Haploid cells, in general, are unstable in culture and have a tendency to undergo endomitosis to form diploid cells. This property of cell culture can be exploited for obtaining homozygous lines of ginger.
Callus formation and the development of roots and rhizome-like structures were reported from excised ginger anthers cultured on MS medium containing 2,4-D and coconut milk (Ramachandran and Nair, 1992).
Samsudeen et al. (2000) reported regeneration of plantlets from excised anthers. They cultured excised anthers with uninucleate pollen mother cells and pollen were inoculated on modified MS medium supplemented with 0.2 to 3.0 mgl-1 2,4-D after cold treatment. Cold treatment was given for 1, 2, and 7 days at 0°C. Of the three different cold treatments tried, callus was induced only from anthers, which had 7 days of cold treatment. These anthers developed friable callus in solid as well as in liquid medium in about 6 weeks. Occasional development of roots was observed in liquid cultures. Their study has shown that solid medium is better than liquid medium for ginger anther culture. 2,4-D at 3 mgl-1 was good for both callus induction and callus proliferation, giving about 3 g of callus in about 30 days of culture when incubated in light. Calli obtained from ginger anthers were cultured on MS basal medium supplemented with 2,4-D (0 to 0.2 mgr1) and BAP (0 to 10 mgl^1). MS medium with 2,4-D at 0.2 mgl^1 and BAP at 10 mgl-1 was the best for organogenesis and plant regeneration. The plant regeneration was by organogenesis and shoot development (see Figure 4.1h). Seventy percent of the cultures gave a morphogenetic response with a range of 1 to 20 shoots and an average of 12.6 shoots per culture tube (see Figure 4.1i). These shoots were multiplied and rooted on MS basal medium with 1 mgl-1 NAA before hardening and field establishment. The regenerated plants are being indexed for the selection of haploids or dihaploids.
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