Chickpea seed cryostorage alters germinant but not adult plant growth
Food security concerns are emerging in many parts of the world due to climate change, disease, and diminishing areas of arable land. Risks to food security can be alleviated by advances in plant biotechnology such as cryopreservation (usually at −196 °C in liquid nitrogen (LN)). While seed cryopreservation methods are being developed for a number of crop species such as chickpea, the scale at which they are implemented is still limited since the effects of cryostorage on subsequent germination, and plant growth and biochemistry are largely unknown. This short communication describes the early stages of germination, emergence and field performance of plants derived from cryopreserved chickpea seeds. Germination and seedling growth were delayed in seeds exposed to LN. Germination percentage of seeds not exposed to LN was 1.18 fold higher than those immersed in LN (99.9% versus 84.3%). Seedling emergence was 1.24-fold higher in control relative to LN exposed seeds (99.6% versus 80.2%). The enzymes superoxide dismutase and peroxidase showed activities higher in seeds exposed to LN in both cases. Superoxide dismutase specific activity was 1.9 folds increased (0.30 U mg−¹ proteins / 0.15 U mg−¹ proteins). Peroxidase specific activity was 1.7 folds increased (4.1 U mg−¹ proteins / 2.3 U mg−¹ proteins). Contrastingly, the total protein level in control seeds was 1.2 fold higher than the LN-exposed seeds (8.98 mg g−¹ fresh weight versus 7.54 mg g−¹ fresh weight). Electrolyte leakage was higher in seeds exposed to LN (1.9 fold increase; 17.4% versus 9.1%), and in the radicles, plumules, roots and leaves derived from these seeds. Electrolyte leakage in radicles showed 1.8 fold-increase (9.1% / 5.1%) and plumules 1.5 fold-increase at 72 h of germination (9.3% / 6.3%). At 7 d of germination, roots showed 1.4 fold-increase (8.9% / 6.3%) and leaves 1.7 fold-increase (17.3% / 10.2%). When adult plants were compared at harvest (110 days after sowing) in terms of thirteen traits there were no significant differences between those produced from cryopreserved and control seeds. It worth mentioning that these traits included both developmental and biomass/yield-related traits. These results suggest that even though cryostorage may reduce in-field seedling establishment rates by compromising germinability to a small degree, the effects of LN exposure on seed and seedling biochemistry are unlikely to affect subsequent plant yield. This validate the use of cryopreservation for the long term storage of chickpea germplasm.