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Jenderek M.M.,U.S. Department of Agriculture | Ambruzs B.,U.S. Department of Agriculture | Tanner J.,U.S. Department of Agriculture | Holman G.,U.S. Department of Agriculture | And 4 more authors.
Acta Horticulturae | Year: 2014

In cryopreservation of germplasm, using dormant winter buds (DB) as source plant material is economically favorable over tissue culture options. Although the DB cryopreservation method has been known for many years, the approach is feasible only for cryopreserving a select number of temperate tree species. The original method developed for Malus (apple) DB, requires desiccation of stem segments (to 25-30% moisture content), slow cooling (to -30°C), storage in liquid nitrogen vapor (LNV) and viability testing by grafting. We investigated the possibility of using this method for cryopreservation of DB of Juglans regia, J. cinerea, Prunus dulcis, P. persica, Salix exigua and S. triandra germplasm. The post LNV viability of P. dulcis, P. persica and S. triandra DB was very low. Dormant buds of J. cinerea harvested in December were viable in a higher percent than buds harvested in January. The fraction of viable SalixDB on 10 cm branch segments was significantly higher (30 and 80%) than on 6 cm long segments (0 and 45%;P>0.05); this indicated that the longer segments might be more suitable for cryopreservation of thetwo Salix species. For Juglans regia, the viability after LNV exposure was evaluated by grafting and forced bud break under high relative humidity conditions and the percent of viable buds was similar forboth methods; hence testing under mist might be a valid indication of viability. The application of the Malus DB cryopreservation method might also be applicable to preservation of almond, peach and English walnut however studies on factors enhancing post LNV viability are needed.

Vollmer R.,International Potato Center Lima | Panta A.,International Potato Center Lima | Tay D.,International Potato Center Lima | Roca W.,International Potato Center Lima | Ellis D.,International Potato Center Lima
Acta Horticulturae | Year: 2014

The effect of shoot tip pre-culture on media with varying sucrose levels (0.0-0.6 M) followed by treatment with Plant Vitrification Solution 2 [PVS2] (15, 30, 45, 60 min) was evaluated with six sweet potato accessions [Ipomoea batatas (L.) Lam.], using the "PVS2-droplet vitrification" cryopreservation method. No significant differences in the percent of shoot regeneration were observed when shoot tips were pre-cultured on sucrose concentrations ranging from 0.1 to 0.4 M. The highest mean shoot regeneration rate of 57.7 ± 5.5% after rewarming from cryopreservation (+LN) was obtained with a sucrose concentration of 0.35 M. Intermediate exposure times in PVS2 of 30 and 45 min showed statistically better results than shorter or longer exposure, with a maximum mean shoot regeneration (+LN) of 68.5 ± 4.5% with a 30 min exposure. Screening a separate larger group of 24 sweet potato accessions with a 0.35 M sucrose pre-culture and 30 min PVS2 treatment (+LN) resulted in shoot formation rates ranging from 1.7 to 66%.

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