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°C for 4 days, (2) anthers were subjected to electric shock treatment of three exponentially decaying pulses of 50–400 V with 25 μF capacitance and 25 Ω 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.