Castanea spp. hybrid clones in vitro conservation: synthetic seeds vs. slow growth storage

F. Gomes, M. Clemente, P. Figueiredo, F. Plácito, H. Machado, C. Santos, R. Costa
Chestnut fruit production has declined due to ink disease (Phytophthora cinnamomi). Hybrid clones produced from controlled crosses between Castanea sativa × C. crenata and C. sativa × C. mollissima were micropropagated to test the susceptibility to P. cinnamomi. Since in vitro clonal conservation is relevant for germplasm preservation, in this work, we compared two different techniques: slow growth storage (SGSt) and synseeds. Sucrose and mannitol concentrations (0.16 and 0.22 M) were tested during SGSt over different storage periods (1, 3 and 6 months). Capsules with nodal segments (5-7 mm) were transferred at three different conservations (empty tubes vs tubes filled with sterile distilled water or 30% glycerol solution). When SGSt was tested, the lowest survival after storage was observed with mannitol. After 6 months of conservation at 4°C and darkness, a high survival percentage (93±1.5%; P<1%) was achieved with 0.22 M sucrose. The best multiplication rate (P<5%) was achieved with 0.16 M sucrose (2.4±0.15) after 1 month and with 0.22 M sucrose (1.83±0.14), after 6 months of cold storage. Synseeds conservation was not affected by neither the Na-alginate and CaCl2 concentration used during encapsulation or conservation period. The lowest survival percentage was observed when 30% glycerol was used and the best result (100%; P<1%) was obtained with sterile distilled water. The germination time ranged from 16-24 days (after 1-6 months). After 6 months the best result of germination rate (85.3%; P<5%) was achieved with sterile distilled water; in the second multiplication cycle, the best result was scored with 100 mM CaCl2/sterile distilled water (1.80±0.25; P<5%). Overall, the best storage treatments for these cultures were achieved with synseeds stored with sterile distilled water and with SGSt with 0.22 M (suc.).
Gomes, F., Clemente, M., Figueiredo, P., Plácito, F., Machado, H., Santos, C. and Costa, R. 2017. Castanea spp. hybrid clones in vitro conservation: synthetic seeds vs. slow growth storage. Acta Hort. (ISHS) 1155:37-44
alginate, C. crenata, C. mollissima, C. sativa, micropropagation, synseeds

Acta Horticulturae