Title: “Seasonal changes in cold hardiness and carbohydrate metabolism in four garden rose cultivars”
See:
“5. Conclusion
The more cold-hardy cultivars (‘John Cabot’ and ‘Dagmar Hastrup’)
acclimated faster and reached their lowest LT50 values in December.
The less cold-hardy cultivars (‘Abraham Darby’ and ‘Chandos Beauty’)
acclimated more slowly and reached their maximum cold hardiness
level in January requiring an extended freezing period. The lowest cell
water content was found in the more cold-hardy cultivars. Acclimation
coincided also with accumulation of oligosaccharides, which were
strongly correlated with LT50 in ‘John Cabot’, ‘Dagmar Hastrup’ and
‘Abraham Darby’.
For the first time, genes linked to dehydrin and carbohydrate metabolism
in roses during cold acclimation were identified in the more
cold-hardy ‘Dagmar Hastrup’ and the less cold-hardy ‘Chandos Beauty’.
Dehydrin transcripts (RhDHN5 and RhDHN6) accumulated significantly
during November-January in both cultivars and were hardly detectable
in April. Different genes in starch and soluble carbohydrate metabolism
were identified and their seasonal expression was studied but no clear
overall trend was found. The cyclic structure of sucrose metabolism
involving sucrose cleavage and energy-demanding re-synthesis via
hexose phosphorylation is clearly cultivar dependent, although our data
also suggest the presence of a temperature response.
Although we found certain distinct trends which separated the more
cold-hardy and less cold-hardy cultivars, other metabolic changes were
genotype independent. In order to have a general and clearer insight of
cold hardiness in roses, more cultivars differing in cold hardiness
should be studied.”