Florent Engelmann

Effects of cryopreservation of Phaseolus vulgaris L. seeds on early stages of germination.

In this work, we studied the effects of cryopreservation on various parameters of early stages of germination of Phaseolus vulgaris seeds (0, 7 and 14xa0days). Percentages of germination, fresh mass of different plant parts, levels of chlorophyll pigments (a, b, total), malondialdehyde, other aldehydes, phenolics (cell wall-linked, free, and total) and protein were determined. No phenotypic changes were observed visually in seedlings recovered from cryopreserved seeds. However, several significant effects of seed liquid nitrogen exposure were recorded at the biochemical level. There was a significant negative effect of cryopreservation on shoot protein content, which decreased from 3.11xa0mgxa0g−1 fresh weight for non-cryopreserved controls to 0.44xa0mgxa0g−1 fresh shoot weight for cryopreserved seeds. On the other hand, cryopreservation significantly increased levels of other aldehydes than malondialdehyde in shoots at day 7, from 56.47xa0μmolxa0g−1 for non-cryopreserved controls to 253.19xa0μmolxa0g−1 fresh shoot weight for cryopreserved samples. Liquid nitrogen exposure significantly reduced phenolics contents (free, cell-wall linked, total) in roots at day 7 after onset of germination. In general, roots were more affected by cryostorage compared with other plant parts, while leaves were the least affected. The effects of seed cryopreservation seem to decline progressively along with seedling growth.

Cryopreservation of Tropical Plant Germplasm with Vegetative Propagation - Review of Sugarcane (Saccharum spp.) and Pineapple (Ananas comusus (L.) Merrill) Cases

Sugarcane (Saccharum sp. hybrids) is a crop of major importance, which is cultivated on a large scale in tropical and subtropical regions primarily for its high sucrose content. Cultivated pineapple (Ananas comosus (L.) Merrill, which is now called Ananas comosus var comosus) belongs to the family Bromeliaceae. It is economically the fourth most important crop worldwide in terms of tropical fruit production and follows banana, mangoes and citrus. One of the main drawbacks faced by sugarcane and pineapple agriculture worldwide is the vegetative (i.e. asexual) nature of its conventional propagation. The consequence is that plants in the field must be replaced at intervals ranging from 1 to 5 years, a process that is costly, tedious and time-consuming. Furthermore, if the planting material is of low quality, yields decrease and more tillage is needed. The crops are exposed to natural disasters, while the propagation system leads to systemic disease transmission, and natural selection and plagues also take their toll. Moreover, the industry is in dramatic need of planting material, which cannot be produced in sufficient quantities to meet the demand using classical macropropagation techniques.

Advances in Cryogenic Techniques for the Long-Term Preservation of Plant Biodiversity

This chapter presents different technical aspects related to the development and large-scale application of cryopreservation techniques, as a biotechnological approach for the long-term storage of plant biodiversity. The main cryogenic procedures and the key steps for their successful adaptation to diverse forms of germplasm are described. Some representative examples of cryopreservation of different plant species are presented to illustrate the significant progress achieved in the practical utilization of cryopreservation as a complementary alternative for germplasm conservation. In addition, other potential uses of this technology to support genetic breeding programs, and its recent utilization to eliminate systemic plant pathogens through cryotherapy are discussed.

Histological characterization of Passiflora pohlii Mast. root tips cryopreserved using the V-Cryo-plate technique

Cryopreservation stands out as the main strategy to ensure safe and cost efficient long-term conservation of plant germplasm, especially for biotechnological materials. However, the injuries associated with the procedure may result in structural damage and low recovery rates after cooling. Histological analysis provides useful information on the effects of osmotic dehydration, LN exposure, and recovery conditions on cellular integrity and tissue organization, allowing the determination of the critical steps of the cryopreservation protocol and, thus, the use of optimized treatments. Passiflora pohlii Mast. (Passifloraceae) is a native species from Brazil with potential agronomic interest. Recent studies showed the presence of saponins in its roots, which presented antioxidant activity. The goal of this work was to develop a cryopreservation technique for root tips of in vitro-derived plants of P. pohlii using the V-Cryo-plate technique and to characterize the anatomical alterations that occurred during the successive steps of the protocol. Root tips were excised from in vitro plants and precultured before adhesion to cryo-plates and then treated for different periods with the plant vitrification solutions PVS2 or PVS3. Treatment with PVS2 for 45xa0min resulted in higher recovery (79%) when compared with PVS3 (43%). The greatest number of adventitious roots per cryopreserved explant was also observed after a 45-min exposure to PVS2. Plasmolysis levels were higher in cortical cells of cryopreserved explants treated with PVS2, while pericycle and central cylinder cells were not damaged after this treatment. Thirty days after rewarming, no plasmolysis could be detected, regardless of the experimental conditions.

Maize seed cryo-storage modifies chlorophyll, carotenoid, protein, aldehyde and phenolics levels during early stages of germination

We recorded the crypreservation effects (direct immersion) on various parameters of early germination stages of maize seeds (0, 7 and 14xa0days). Percentages of germination; fresh mass of different seedling parts; levels of chlorophyll pigments (a, b); carotenoids; malondialdehyde; other aldehydes; phenolics (cell wall-linked, free) and proteins were determined. Various statistically significant effects of seed exposure to liquid nitrogen (LN) were recorded. Maize seeds did not seem to be affected by LN exposure either visually or regarding fresh weight or germination rate. However, delayed growth was observed in seedlings recovered from cryopreserved seeds. This trend indicated an increase in the effect of seed cryopreservation on growing plants. The most significant effects of LN exposure were recorded in the combined fresh weight of stems and leaves at day 7 of germination and in fresh weights of roots, stems and leaves at day 14. At the biochemical level, numerous indicators varied following LN exposure, but the most significant effects were recorded in carotenoids, malondialdehyde and other aldehyde contents. LN exposure modified 50.0% of indicators in cotyledons, 48.1% in stems and leaves, 38.8% in roots and 11.1% in seeds. LN storage modified 11.1% of the variables measured at day 0 of germination, 37.0% at day 7, and 52.7% at day 14. Field performance of cryostored seed-derived plants should be evaluated to measure the durability of the changes observed.