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United States Department of Agriculture

Agricultural Research Service

Research Project: MANAGEMENT OF TEMPERATE FRUIT NUT AND SPECIALTY CROP GENETIC RESOURCES Title: Ultrastructure study of apple meristem cells during cryopreservation

Authors
item Kushnarenko, S. -
item Kovalchuk, I. -
item Mukhitdinoval, Z. -
item Rakhimoval, E. -
item Reed, Barbara

Submitted to: Asian and Australasian Journal of Plant Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 10, 2010
Publication Date: July 10, 2010
Citation: Kushnarenko, S., Kovalchuk, I., Mukhitdinoval, Z., Rakhimoval, E., Reed, B.M. 2010. Ultrastructure study of apple meristem cells during cryopreservation. Asian and Australasian Journal of Plant Science and Biotechnology. 4:10-20.

Interpretive Summary: Cold treatment of plants causes changes in the cell structure and contents. These changes result in the ability of plants to survive cold temperatures and storage in liquid nitrogen (cryopreservation). The internal cell structure of the growing shoot tip cells of apple was studied before and after cold treatment and during the steps of a cryopreservation procedure. Two cultivars , Grushovka Vernenskaya and Voskhod, were studied. Cells of the two cultivars were similar in size in all treatments. The control cells and cells recovered after cryopreservation were the smallest and significantly smaller than the cold treated cells or those measured at several steps of the protocol. Cells of both cultivars increased in both length and width with the cold and other treatments, and then decreased after rewarming. Electron microscopic examination showed intense starch accumulation inside ‘Grushovka Vernenskaya’ after three weeks cold treatment while ‘Voskhod’ had small starch grains. Overall the treatments in the protocol caused the cell size to increase when compared to the untreated cells and cells that were regrown after cryopreservation. This study contradicts the conventional thought that cryoprotective treatments cause cells to decrease in size, thus allowing greater survival.

Technical Abstract: The ultrastructure of apple (Malus x domestica Borkh.) meristem cells was studied before and after cold acclimation (CA) and during the steps of PVS2 vitrification. We compared cells of in vitro grown shoots of two cultivars, Grushovka Vernenskaya and Voskhod. Cells of the two cultivars were similar in size in all treatments. The control cells and cells recovered after LN exposure were the smallest and significantly smaller than the CA, sucrose treated and PVS2 treated cells. Cells of both cultivars increased in both length and width with CA, sucrose and PVS2 treatments, and then decreased after rewarming. Electron microscopic examination showed intense starch accumulation inside plastids of ‘Grushovka Vernenskaya’ after three weeks CA while ‘Voskhod’ plastids had small starch grains and two types of plastoglobules. Two types of small vacuoles were noted in acclimated meristem cells of ‘Grushovka Vernenskaya’; one was electron-transparent with many vesicles and sediments, and the other had electron-opaque contents. There were interwoven membranes and occasional dark flecks in the vacuoles of ‘Voskhod’ acclimated cells. Sometimes large globules with the density and structure similar to polyphenolic compounds were observed. Overall the treatments in the protocol caused the cell size to increase when compared to the untreated cells and cells that were regrown after cryopreservation. This study contradicts the conventional thought that cryoprotective treatments cause meristem cells to decrease in size, thus allowing greater survival.

Last Modified: 11/24/2014
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