Cryotolerance of apple tree bud is independent of endodormancy

Abstract

Increasing interest in cryopreservation of dormant buds reveals the need for better understanding of the role of dormancy in cryotolerance. Dormancy stage and low-temperature survival of vegetative apple buds (Malus domestica Borkh.), cultivars ‘Sampion’ and ‘Spartan’, collected from orchard were evaluated during three seasons contrasting in temperature and precipitation throughout the arrested plant growth period. During each season, the cultivars differed either in the onset of the endodormancy or in the length of the endodormant period. A simple relation between endodormancy of the buds and their water content was not detected. The cryosurvival of vegetative apple buds of both cultivars correlated with their cold hardening without direct regard to their particular phase of dormancy. The period of the highest bud cryotolerance after low-temperature exposure overlapped with the endodormant period in some evaluated seasons. Both cultivars had the highest cryosurvival in December and January. The presented data were compared with our previous results from a dormancy study of in vitro apple culture. Endodormancy coincided with the period of successful cryosurvival of apple buds after liquid nitrogen exposure, but as such, it was not decisive for their survival and did not limit their successful cryopreservation.

Time-Resolved Analysis of Candidate Gene Expression and Ambient Temperature During Bud Dormancy in Apple

“…The expression peaks occurred approximately 1 week later in ‘Pinova’ compared with ‘Gala.’ In A. thaliana, ICE1 is an inducer of the cold acclimation pathway that leads to freezing tolerance. Although freezing tolerance overlaps with endodormancy, it appears to be independent of endodormancy ( Bilavcik et al, 2015 ). Furthermore, evidence exists that ICE1 can activate FLC expression ( Lee et al, 2015 ).…”

Analysis of freezable water content by DSC for apple dormant bud cryopreservation

“…Furthermore, cryopreservation success seemed to be unaffected by collecting the scions later than until half of January, as recommended (Towill et al 2004;Bilavcik et al 2015). Most of genotypes collected on January 21 and February 4 showed similarly good results such as genotypes collected on January 5 and January 7 -this was probably due to long-lasting winter in 2010.…”

“…In case of 'Sampion' collected on January 21 in mother orchard of Sempra Litoměřice showed regeneration of 84%, while the same variety collected on January 5 in orchard of CRI showed regeneration of 100% (Table 1). Physiological stages of various trees in various seasons seem to affect their regeneration abilities after cryopreservation too (Forsline et al 1998b, Bilavcik et al 2015. The suitable weather in winter 2010 could also play a role in regeneration rates.…”

“…Further investigation in mechanisms and physiological aspects of cryopreservation is continuing in Europe e.g. Denmark (Toldam-Andersen et al 2007;Vogiatzi et al 2010;Bilavcik et al 2015), Germany (Höfer 2007), where some cultural apple varieties and landraces were successfully cryopreserved following the protocols developed at the USDA-ARS, USA. In the Czech Republic, apple dormant buds have not been cryopreserved until now, although this method is very worthwhile for the long-time protection of old regional varieties, which are grown in orchards in the Czech Republic.…”

Cryobiotechnology of Plants: A Hot Topic Not Only for Gene Banks

“…For plant regeneration, recovered scions with dormant buds are grafted directly on pot-grown rootstocks, or it is also possible to excise shoot tips from cryopreserved buds and place them on culture medium [95]. Successful regeneration of cryopreserved buds is tightly linked with the cold hardening of these buds before cryopreservation, rather than with the phase of endodormancy [96].…”