Effect of spikelet position on rice anther culture efficiency.

The potential of anthers from different parts of the panicle to induce callus was investigated with the japonica rice variety Taipei 309. The results showed that the callusing abilities of anthers from different spikelet positions were significantly different. After plating 4483, 4496, 4348 anthers from the basal, middle and top parts, the percentage of anthers forming calli was 20% in the basal part, 12% in the middle part and 8% in the top part. The anthers of basal parts containing pollen at all uninucleate stages, including early, middle and late, showed higher callus induction frequency than those from middle and top parts. The green plantlet regeneration frequencies of top, middle and basal spikelets were around 18% in all three cases. From the results it would appear that anthers from the basal part of the panicle should be used in anther culture of rice in order to obtain higher efficiencies, and thereby optimise the usefulness of this technique in rice breeding programmes.

Increasing anther culture efficiency in rice (Oryza sativa L.) using anthers from ratooned plants.

Anther culture response for the variety Taipei-309 was compared using anthers of ratooned and non-ratooned plants. Anthers were plated onto N6 liquid media with 0, 2, 5, and 10 mg l(-1) ABA, respectively. After 5 days in culture, the media were removed and N6 medium without ABA was added. A higher number of pre-mitotic P-pollen grains were observed in anthers from ratooned plants. A significant synergistic effect was found between anthers from ratooned plants/ABA concentrations and the increase in embryogenic-like structures (ELS) induction and green plant regeneration efficiency. The highest frequency of anthers producing ELS was found in N6 medium (6% Sucrose and 2 mg l(-1) 2,4-D) with 5 and 10 mg l(-1) ABA for anthers derived from ratooned plants. Mean green plant regeneration efficiencies were raised from 24.2 to 42% (non-ratooned), and from 30 to 70%, (ratooned donor plants) using a combination of 10 mg l(-1) ABA in induction media, and MS with 2 mg l(-1) BAP, 1 mg l(-1) NAA, 2 mg l(-1) kinetin and 0.45% agarose. The highest number of green shoots per ELS were obtained from ratooned-derived anthers (up to 82). The use of ratooned plants in anther culture, its importance and relative advantages are also discussed.