K. Dorffling et al., IN-VITRO-SELECTION AND REGENERATION OF HYDROXYPROLINE-RESISTANT LINESOF WINTER-WHEAT WITH INCREASED PROLINE CONTENT AND INCREASED FROST TOLERANCE, Journal of plant physiology, 142(2), 1993, pp. 222-225
An embryogenic callus obtained from immature embryos of a Finnish wint
er wheat (Triticum aestivum L. cv. Jo 3063) was used for in vitro-sele
ction of hydroxyproline (Hyp) resistant calli. Calli were plated on so
lid Gamborg B5 medium containing 10 -20 mM Hyp and 2 mg L-1 2,4-D. Fro
m 6018 embryogenic calli exposed to Hyp in the course of three subcult
ures nine calli proved to be Hyp-resistant and remained viable and emb
ryogenic. These were transferred to a regeneration medium and finally
to Gamborg B5 medium before being transplanted to soil. The regenerate
d plants were grown at 18-degrees-C for 6 weeks and then cold hardened
at 2-degrees-C for 18 weeks. The mean osmotic potential of the Hyp-re
sistant cold hardened regenerates was significantly lower than that of
hardened controls. At the same time their mean proline content and th
eir mean frost tolerance were significantly higher compared with regen
erated controls.