Cryopreservation of Gladiolus cultivars

Cryopreservation is an important technique in the long-term storage of plant germplasm. It can be less labor intensive and more reliable for preventing the loss of plants to disease than multiplying plants in the field or in vitro. The objective of this study was to develop a cryopreservation procedure to preserve our transgenic lines of Gladiolus without growing them each year under the special conditions required for cultivation of genetically engineered plants. Shoot tips, including its meristem were excised from in vitro-grown cormels of cultivars 'Peter Pears' and 'Jenny Lee' and field-grown breeding lines 02-943A, 02-900, and 02-926. Cormels were stored at 4 degrees C for at least six months prior to their use. Excised shoot meristems, 1-2 mm, from all five genotypes were cultured on MS medium supplemented with either 2.0 mg/L kinetin, 0.5 mg/L BA, 0.5 mg/L iPA, 0.5 mg/L BA combined with 0.5 mg/L NAA, 0.5 mg/L iPA combined with 0.5 mg/L NAA, or without hormones. A maximum 70-100% regrowth of the excised shoot tips occurred for the five genotypes. Both 'Peter Pears' and line 02-943A were then used for vitrification. The highest regrowth of shoot tips (54%) using the cultivar 'Peter Pears' was achieved when the shoot tips had been incubated for 2 h in PVS2. Regrowth of vitrified shoots from breeding line 02-943A was only 15% indicating the need to optimize conditions for each genotype. All shoots that survived vitrification showed a phenotypically normal growth in vitro.