Effect of X-ray Irradiation on Maize Inbred Line B73 Tissue Cultures and Regenerated Plants
1988
Wang, A. S. | Cheng, D. S. K. | Milcic, J. B. | Yang, T. C.
In order to enhance variation induced by the tissue culture process and to obtain agronomically desirable mutants, friable embryogenic tissue cultures of maize (Zea mays L.) inbred line B73 were x-ray irradiated with 11 doses [0–8.4 kilorads (kR)]. Reductions in callus growth rate and embryogenic callus formation occurred with increasing x-ray doses 20 d and 3 months (90 d) after irradiation. Callus irradiated with 0.8 kR showed a significant increase in growth rate and a 20% increase in embryogenic callus 9 months (270 d) after irradiation. A total of 230 R₀ plants were regenerated for evaluation. Pollen fertility and seed set of R₀ plants decreased with increasing x-ray dosage. Days to anthesis and plant height of R₀ plants varied among x-ray treatments but were generally reduced with higher dosages. The number of chromosomal aberrations increased with x-ray dosage. The R₁ seeds taken from R₀ plants were also grown and tested for mutant segregation. Plants regenerated from irradiated calli had a two- to 10-fold increase in mutations over plants regenerated from unirradiated control callus. Germination frequency of seeds from R₀ plants decreased with increasing x-ray dosage. Although chlorophyll mutants were most frequently observed, a number of vigorous plants with earlier anthesis date were also recovered. Cooperative investigations of Sungene Technologies Corp. and Lawrence Berkeley Lab.
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