بررسی امکان نگهداری جوانه های انتهای و جانبی، بذر و سلول های گیاهی حاصل از کشت بافت تعدادی از گونه های جنگلی، مرتعی و بیابانی در دمای فراسرد

Besides the common and classic methods of preserving plant species, which includes protected woodlands, botanic gardens and seed banks, cryopreservation or storage at -196 C is a unique method of preserving plant species. Using this technology, most of the seeds, vegetative organs, as well as plant cells can be stored for a long period. This program consisted of 6 research projects including: 1- Cryopreservation of Seeds of Some of the Forest Species, 2- Cryopreservation of Seeds of Some of the Range and Desert Species, 3- Study on possibility of cryopreservation of apical and axillary buds of the range and desert species, 4- Study on possibility of cryopreservation of apical and axillary buds of the forest species, 5- Cell suspension cryopreservation of some of the range and desert species, 6- Cell suspension cryopreservation of some of the forest and woody trees. In the first project, seeds of the following range and desert species collected from different habitats: Ammodendron persicum, Centaurea lachnopus, Camphorosma monspeliaca, Kelussia odoratissima, Ferula gummosa, Medicago polymorpha, Medicago rigidula, Medicago sativa, Secale montanum, Smirnovia iranica and Trifolium radicosum. Before transferring the sample seeds into liquid nitrogen at -196 C, three pretreatments including Vitrification (using PVS2), Desiccation and 30% Glycerol were applied. Depends on plant species liquid nitrogen incubation times of the seeds were 1 week up to 26 month. After removal of the seeds from liquid nitrogen, they were exposured to a heat shock (+42 C), washed, and evaluated by standard germination tests. Furthermore, the second samples of the same seeds were sown in pots and grown in greenhouse (22 4 C). Seed germination, root and shoot lengths, germination speed, root/shoot length ratio and seed vigor index (VI) were recorded and statistically analyzed. High level of recovery from liquid nitrogen (-196 C), seed germination, and other attributes, in either laboratory or greenhouse conditions, revealed the cryogenic (- 196 C) tolerance of all of the species. The plants originated from cryopreserved seeds and grown under greenhouse conditions grew normally and did not show any abnormality when compared to those of control plants. Use of this technology, seeds of the range and desert species can be collected from different habitats and preserved for a long period. In the third project, seeds the following range and desert species were collected from different habitats: Ferula gummosa, Lilium ledebourii, Medicago polymorpha, Medicago rigidula, Salvia leriifolia, Secale montanum and Smirnovia iranica (Synm. S. turkestana). The seeds germinated and grow to seedlings under sterile conditions. Shoot proliferation achieved via application of tissue culture methods and, proliferated shoot buds were excised and treated using Vitrification (PVS2) and Encapsulation- Dehydration methods. The treated shoot buds incubated in liquid nitrogen for 1 week. After removal of the shoot buds from liquid nitrogen, they were exposured to a heat shock (+42 C), washed, and transferred onto solid growth media. Survivability and growth of the cryopreserved shoot buds were evaluated under in vitro culture conditions. In Vitrification method, higher percentage of survivability and growth were observed in Secale montanum buds (41%) followed by Ferula gummosa (28%), Medicago rigidula (23%) and Medicago polymorpha (8%). However, in Salvia leriifolia and Lilium ledebourii survivability and growth did not observe. In Encapsulation- Dehydration method, highest survivability and growth observed in Smirnovia iranica (100%), followed by Medicago rigidula (16%), Medicago polymorpha (16%), Secale montanum (11%) and Ferula gummosa (4%). Survivability and growth of Smirnovia iranica and Ferula gummosa embryos were 86% and 78% respectively. Regarding the survivability and growth figures, species gave different responses to the Vitrification and Encapsulation-Dehydration methods under cryogenic storage. The results also showed that buds and embryos of most of the range and desert species are highly cryo-tolerant compare to those of forest species (see below).