Field performance of cryopreserved seed-derived tomato plants and post-thaw survival of viral-infected meristems

The effectiveness of different cryopreservation techniques of tomato meristems isolated from viral-infected plants ‘Irishka’ cultivar was determined. The pieces of stem were protected with dimethyl sulfoxide and propylene glycol and cooled in vapour phase of liquid nitrogen (–170 °C). For the vitrification and droplet-vitrification protocols, the meristems were treated with loading solution and dehydrated with different plant vitrification solutions (PVS1 modified, PVS2, 88 % PVS3, PVSN). The samples were placed to sterilized aluminum foil pieces, in 1.2 ml cryovials or in 50 µl aluminum pans for differential scanning calorimetry and were directly immersed into liquid nitrogen. Acсording to the dehydration technique, the meristems were dehydrated with sterile airflow for 120 min. The post-thaw survival rates of meristems (from 34.2 to 78.5 %) were observerved only for 50 µl aluminum pans and airflow dehydration. We determined the productivity of plants, obtaned from cryopreserved seeds (‘Seven’, ‘Potiron Ecarlate’ and ‘Druzhba’ cultivars). We observed increasing in total and marketable yields for the plants grown from the cryopreserved seeds for all the cultivars. Total number of diseased plants decreased by 33 % for ‘Seven’, for ‘Potiron Ecarlate’ it did by 6.7 %, for that of ‘Druzhba’ the total percentage of sick and healthy plants did not differ after seeds cryopreservation

Post-Thaw Survival of Meristems from In Vitro Sweet Potato (Ipomoea batatas (L.) Lam.) Plants

Cryotherapy of shoot tips can effectively eliminate the sweet potatoes pathogens, such as viruses and phytoplasm, and is impossible without the development of effective cryopreservation techniques. At the same time, cryopreservation allows a long-term germplasm storage. In this study, we developed and compared different methods for sweet potatoes’ meristems treatment for optimized preservation. The meristems of Admiral variety up to 1–2 mm were isolated from in vitro growth plants. In one group the specimens were dehydrated for 120 min with sterile air flow and immersed into liquid nitrogen at a needle tip. The meristems of other groups were dehydrated with plant vitrification solutions (modified PVS 1, PVS 2, 88% PVS 3, and PVS N). The samples were immersed into liquid nitrogen either in 1.8 mL cryovials or 50 µL hermetically sealed aluminum pans for differential scanning calorimetry. It was shown that the survival rates of meristems were 55% after 88% PVS 3 treatment and 83 and 85% after PVS 2 and PVS N exposure. The highest percentage of preserved specimens was found after dehydration with air-flow and modified PVS 1 (89–95%). After cryopreservation in 1.8 mL cryovials the highest post-thaw preservation was noted after pretreatment with modified PVS 1 (60–75%) and the lowest one was observed with 88% PVS 3 (35–40%). Meristems treated with PVS 2 and PVS N provided 45–55% survival rates. After cryopreservation in aluminum pans the highest post-thaw preservation was detected for dehydration with modified PVS 1 (81–84%) and the lowest one was found with 88% PVS 3 (40–51%). Meristems treated with PVS 2 and PVS N revealed of 68–78% post-thaw survival respectively. The meristems cryopreservation method based on dehydration with sterile air flow is of special interest, since no cryoprotectant use is needed