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ARS Home » Pacific West Area » Corvallis, Oregon » National Clonal Germplasm Repository » Research » Publications at this Location » Publication #117209
Title: PRECULTURE CONDITIONS INFLUENCE CRYOPRESERVATION AND COLD HARDINESS OF PYRUS CORDATA SHOOT TIPS

Author
item CHANG, YONGJIAN - OREGON STATE UNIVERSITIY
item Reed, Barbara

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2001
Publication Date: 12/1/2001
Citation: N/A

Interpretive Summary: Cold hardiness and survival following liquid nitrogen exposure (cryopreservation) of micropropagated pear shoots were evaluated after growth on tissue culture medium with a dormancy chemical, abscisic acid, (ABA) and sucrose or at low temperatures (LT). Low temperature treatments were the most effective pretreatments for increasing shoot cold hardiness and growth of cryopreserved pear shoot tips. Without LT treatment, ABA and sucrose in the culture medium decreased water content but only slightly increased cold hardiness and tolerance to liquid nitrogen. ABA and sucrose effects were greatly enhanced when combined with LT treatment. Shoot tips and lateral buds were the most cold hardy (-22.5 and -20.1) with the combined LT-ABA treatment. The optimal shoot pretreatments for successful recovery of cryopreserved pear shoot tips, 3-week culture on either 50 uM ABA or 5-7% sucrose medium followed by 2-week LT, increased shoot tip growth from zero to greater than 70%.

Technical Abstract: Cold hardiness and cryogenic survival of micropropagated pear (Pyrus cordata Desv.) shoots were evaluated after pretreatments with abscisic acid (ABA) and sucrose. Shoot cold hardiness increased by 3oC, and cryopreserved shoot tip growth icreased by 16.7% after a 4-wk 150 uM ABA pretreatment. Low temperature (LT) pretreatments improved the recovery of cryopreserved P. cordata shoot tips. Six to 10 wk of LT were required for reaching high cryopreservation recovery. ABA and LT treatments produced significant synergistic effects on both cold hardiness and cryopreservation recovery. ABA shortened the LT requirement for high cryopreservation growth from 10 wk to 2 wk. The optimal treatment for recovery of cryopreserved shoot tips was 3-wk culture on 50 uM ABA and 2-wk LT, while the maximum cold hardiness (-22.5 oC) was obtained with 150 uM ABA and 2-wk LT. Four-wk culture on 150 uM ABA at 25oC induced dormancy in 74% of shoot tips but had little effect on cryopreservation growth unless combined with LT. ABA and LT produced different levels of cold hardiness for leaves, nodes, and shoot tips. Control and ABA-treated shoot tips, lateral buds and leaves had similar cold hardiness, but LT and LT+ABA- treated shoot tips survived the lowest temperatures, lateral buds next, and finally leaves. An increase in the preculture-medium surose concentration from 2 to 7% combined with 2-wk LT significantly increased cryopreserved shoot tip growth (0% to 75%) and a decrease in the LT50 from -7.8 to -12.4oC.