Direct Shoot Regeneration from Strawberry Leaf Disks

Abstract

An efficient and reproducible method of direct shoot regeneration from leaf disks in strawberry ( Fragaria × ananassa cv. Redcoat) has been developed. The influence of hormone concentration, light intensity, orientation of leaf disk, and age of explant source on shoot regeneration was examined. Regeneration of leaf disks reached 94%, with an average of 13 shoots per leaf disk, within 8 weeks when MS salts and B-5 vitamins medium supplemented with 10 μ m each of BA and IAA were used. The adventitious shoot meristems initially arose from epidermal or sub-epidermal cells at the periphery of the leaf disks and later from surface cells of the newly regenerated meristems. Shoot regeneration did not depend on light, but low light intensity (12.5 μmol·s −1 m −2 ) greatly enhanced regeneration. The leaf disks obtained from 30-day-old greenhouse plants and from young runner plants produced shoots at higher frequency than those obtained from 1-year-old plants. Regeneration frequency was higher when the adaxial surface of leaf disks was kept in contact with the medium surface. Shoot regeneration also occurred in nine other genotypes at varying frequencies, but with an intervening short callus phase, except in ‘Veestar’. The technique has potential application for rapid propagation and genetic manipulation of strawberries.