Effects of abscisic acid on wheat callus cultures

In tissue culture, use of various plant growth regulators has been shown to modify callus growth and plant regeneration rates. This study examined the effects of 0.5, 1.0, 1.5 and 2.0 mu M concentrations and two modes of application of abscisic acid (ABA), namely in the medium and topical application, on callus growth and plant regeneration of two wheat (Triticum aestivum L.) genotypes, PI 137739 and 'Stephens'. Callus induction and proliferation were arrested by ABA treatments in the first month. Enhanced growth of up to 3-fold was observed in ABA treated calli compared to control when they were transferred to maintenance medium without ABA in the second month. In 'Stephens', increased plantlet production was observed when ABA was incorporated in the medium. Thus, wheat genotypes responded differently to ABA treatments with regards to calli growth and plant regeneration capability.