MAIZE ANTHER CULTURE : IMPROVEMENT OF THE PLANT REGENERATION EFFICIENCY IN DIFFERENT THAI GERMPLASMS

摘要

Two different regeneration protocols were compared for their suitability in maize anther culture, i.e., 1) transferring anthers to regeneration conditions after anthers were incubated on induction medium for 2-4 weeks, i.e., prior to the appearance ofmacroscopic embryo-like structures ("early-transfer" treatments), 2) transferring macroscopic embryo-like structures (= ES) to regeneration conditions after anthers were incubated on induction medium for 5-9 weeks (= control treatment). Generally, early-transfer treatments caused a decline of the ES production by 50% or more; the earlier the transfer was conducted, the stronger was the decline. However, the plant regeneration frequency greatly was improved by early-transferring. Optimal effects were attained with a transfer to regeneration medium after 21 days; using a highly androgenetic genotype, 18.9 plants could be regenerated from 100 ES compared to 3.3 in the control treatment. Thus, although less ES were produced, the overall plant production,i.e., the number of plants produced by 100 inoculated anthers, was superior in the early-transfer treatments (4.7 compared to 3.3). Application of the early-transfer treatment (21 d) to a range of 34 Thai genotypes revealed a positive androgenetic response (i.e., ES formation) in 80 % of the tested genotypes; in 40% of the responding genotypes, plant regeneration was observed. Plant regeneration occurred preferably in the early-transfer treatment.