Cryopreservation of seeds of Neonotonia wightii Wight and Arn: a strategy for conservation, dormancy breaking and preservation of nutritional status.

BACKGROUND: N. wightii (Leguminosae) is valued as a cover crop and as a potential source of protein in food insecure countries. However, plantlet establishment is limited by physical dormancy. Our previous work has shown that exposure of N. wightii seeds to cryogenic temperatures is able to overcome physical dormancy. OBJECTIVE: The current study is an extension of that work where the field performance and nutritional composition of plants regenerated from N. wightii seeds was investigated. RESULTS: It was evident that plants regenerated from cryopreserved seeds displayed faster growth rates than those from control seeds. In addition, cryopreservation did not alter the nutritional profile of plants produced from cryo-stored seeds. CONCLUSION: Collectively, the results indicate that cryopreservation serves as a suitable strategy for the preservation of seeds of N. wightii with the added benefit of also serving as a dormancy breaking mechanism upon retrieval from cryogenic temperatures. Doi.org/10.54680/fr23510110712.

Cryopreservation of seeds of the highly valued tropical timber species Swietenia mahagoni.

BACKGROUND: Swietenia mahagoni wood is one of the most valuable in world trade and, as a result, natural populations have been decimated due to unsustainable harvesting. The decline in natural population levels is being exacerbated by climate change. In order to ensure the preservation of valuable genotypes, there is an urgent need to develop strategies to conserve the genetic diversity present within this species. At present, cryopreservation is the most viable option for the long-term storage of plant germplasm, particularly for long-lived species which are challenging to maintain in the field. OBJECTIVE: To cryopreserve intact seeds of S. mahagoni, with the dual goal of retaining the biosynthetic capacity of plants, which is critical since this species is highly valued for medicinal purposes. MATERIALS AND METHODS: Seeds at a moisture content of 6% were immersed in liquid nitrogen (LN) before warming and recovery. Plantlet establishment and growth were assessed over a period of 70 days and anthraquinone synthesis was determined in roots, stems and leaves. RESULTS: The results showed an initial lag in the germination rate of cryopreserved seeds compared with control seeds; however, this difference disappeared over time. The lag in seedling emergence observed in cryostored seeds was also evident in the plant characteristics measured following 30 days of culture when all plant parameters measured were significantly higher in plants produced from control than cryostored seeds. However, after 70 days of growth, these differences were no longer apparent. Anthraquinone levels were also initially lower (at 30 days) in plants regenerated from cryopreserved seeds than those from control seeds, however, this difference was substantially reduced by 70 days thereby indicating the ability of these plants to accumulate secondary metabolites, albeit at a reduced rate, during the early stages of development. CONCLUSION: In S. mahagoni, the delay in anthraquinone production in plants regenerated from cryostored seeds during the early stages of development may have occurred as a consequence of the preferential allocation of resources towards the initiation of recovery processes in response to the stresses imposed by cryopreservation. Once the stresses were overcome and plant growth resumed, resources could be directed to secondary processes such as anthraquinone synthesis. doi.org/10.54680/fr22610110412.

Exposure of Teramnus labialis (L.F.) Spreng Seeds to Liquid Nitrogen Does Not Affect Nutritional Status of Field Grown Adult Plants.

BACKGROUND: Teramnus labialis (L.f.) Spreng is a potentially important legume species, and can be used as an animal feed and to enhance soil physicochemical characteristics. Despite the biological and agricultural importance, the low availability of seeds, their small size and the low percentage germination limit their large-scale use by farmers. We previously reported a method to cryopreserve seeds of T. labialis which also allowed for the breaking of seed dormancy. OBJECTIVE: The current study reports on the nutritional status of 5 month old field grown plants regenerated from cryostored and control seeds. MATERIALS AND METHODS: Biomass (fresh and dry mass of leaves and stems) and contents of ash, neutral detergent fiber, acid detergent fiber, lignin, cellulose, crude protein, P, Ca, Mg and K were measured. RESULTS: Seeds germinated and emerged faster following immersion in liquid nitrogen (LN) which was supported by quantitative evaluations of fresh and dry weights per m2. However, the ratio of leaf:stem mass were not altered by seed exposure to LN. CONCLUSION: The results showed that exposure of seeds to cryogenic temperatures did not alter the nutritional composition of regenerated plants.

Seed Cryostorage Enhances Subsequent Plant Productivity in the Forage Species Teramnus Labialis (L.F.) Spreng.

BACKGROUND: Teramnus labialis is an herbaceous legume that serves as a source of carbohydrates and proteins for animals and humans, and is valued for its nitrogen contribution to soil. The benefits of this species are, however, limited by low seed availability, small seed size and low in situ seed germination levels, due to physical dormancy. Cryostorage has been shown to be beneficial for both seed storage and breaking physical dormancy in seeds of various species. However, its potential effects on subsequent seedling emergence, plant growth and seed production need to be studied before large-scale implementation for T. labialis. OBJECTIVE: To record agricultural traits of T. labialis after seed exposure to liquid nitrogen. MATERIALS AND METHODS: Seeds were maintained at 5 degree C (control) or stored in LN before sowing. Seedling emergence percentage and traits related to plant growth and seed production were evaluated for 6 months. RESULTS: Except for seed weight, all traits differed significantly between seedlings generated from cryostored and control seeds. Except for pod number, seedling emergence and plant growth traits were enhanced by cryostorage to a greater extent than seed production traits. Cryostorage resulted in cracks and breaks in the seed coat which were absent in control seeds (scanning electron microscopy), and in breaking physical dormancy may have facilitated more rapid seedling emergence than for control seeds. CONCLUSION: Seed cryostorage enhances subsequent plant productivity in terms of growth and to a lesser extent seed production in Teramnus labialis, validating its use for commercial growth of this species.

Effect of cryopreservation on the structural and functional integrity of cell membranes of sugarcane (Saccharum sp.) embryogenic calluses.

In this paper, we investigated if the differences consistently noted in survival and plantlet production between cryopreserved and non-cryopreserved, control sugarcane embryogenic calluses were related to modifications induced during cryopreservation in the structural and functional integrity of cell membranes. For this, the evolution of electrolyte leakage, lipid peroxidation products and cell membrane protein contents was measured during 5 d after cryopreservation. Differences between control and frozen calluses were observed only during the first 2 (electrolyte leakage) or 3 d (lipid peroxidation products and membrane protein content) after freezing. It was not possible to link these differences with the differences noted in survival and plant production between control and cryopreserved calluses. Additional studies are thus needed to elucidate which biochemical factors, linked to survival and plantlet regeneration, are affected by cryopreservation.

Field performance of sugarcane (Saccharum sp.) plants derived from cryopreserved calluses.

This study compared the field performance of sugarcane plants originating from three different sources: control, non-cryopreserved embryogenic calluses, cryopreserved embryogenic calluses and macropropagated material of the same commercial hybrid. Several agronomic traits were evaluated on 100 plants per treatment over a 27-month period covering the growth of the stool and of the first ratoon. Significant differences between treatments were observed only during the first six months of field growth of sugarcane stools. Stems produced from in vitro cultured material, irrespective of their cryopreservation status, had a smaller diameter and a shorter height than those produced from macropropagated material. These differences disappeared by 12 months of stool field growth.