Doubled-haploid production in chickpea (Cicer arietinum L.): role of stress treatments.

This is the first report on the production of double-haploid chickpea embryos and regenerated plants through anther culture using Canadian cultivar CDC Xena (kabuli) and Australian cultivar Sonali (desi). Maximum anther induction rates were 69% for Sonali and 63% for CDC Xena. Under optimal conditions, embryo formation occurred within 15-20 days of culture initiation with 2.3 embryos produced per anther for CDC Xena and 2.0 embryos per anther for Sonali. For anther induction, the following stress treatments were used: (1) flower clusters were treated at 4 degrees C for 4 days, (2) anthers were subjected to electric shock treatment of three exponentially decaying pulses of 50-400 V with 25 microF capacitance and 25 Omega resistance, (3) anthers were centrifuged at 168-1,509g for 2-15 min, and finally (4) anthers were cultured for 4 days in high-osmotic pressure (563 mmol) liquid medium. Anthers were then transferred to a solid embryo development medium and, 15-20 days later, embryo development was observed concomitant with a small amount of callus growth of 0.1-3 mm. Anther-derived embryos were regenerated on plant regeneration medium. Electroporation treatment of anthers enhanced root formation, which is often a major hurdle in legume regeneration protocols. Cytological studies using DAPI staining showed a wide range of ploidy levels from haploid to tetraploid in 10-30-day-old calli. Flow cytometric analysis of calli, embryos and regenerated plants showed haploid profiles and/or spontaneous doubling of the chromosomes during early regeneration stages.