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The present study reports the development of in vitro micropropagation protocols for Ekebergia capensis Sparrm., a species that produces unstorable recalcitrant (non-orthodox) seeds. Suitable protocols were established for shoots generated from nodal segments excised from in vitro-germinated seedlings, and for adventitious shoots generated from intact in vitro-germinated roots. Difficulties were experienced when attempts were made to micropropagate germplasm from established saplings. The protocols developed have important applications for the conservation (cryopreservation and clonal multiplication) of germplasm of this species. [ABSTRACT FROM AUTHOR]

Background: Cryopreservation currently represents the most suitable strategy for the long-term conservation of plant germplasm. While much effort has focused on the development of protocols to enable successful cryostorage, there are few, if any reports, that consider the effect of cryogenic temperatures on the phytohormone status of the seed and developing seedlings., Objective: To investigate the effect of cryopreservation on external seed coat features as well as levels of indole-3-acetic acid (IAA), abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylic acid (ACC) in maize., Materials and Methods: Two groups of seeds at 6% moisture content were compared: one was maintained at 4 degree C (control) while the other was exposed to LN within cryo-vials., Results: Seeds exposed to cryogenic temperatures were characterized by the presence of large cracks in the seed coat compared with control seeds. Cryogenic exposure also resulted in a reduction in biomass and plant height. Results from the phytohormone analysis showed an initial reduction in the levels of IAA, ABA and ACC after 7 days of growth followed by sharp increase in levels relative to the control by 14 days. Whilst the roles of ABA and ethylene (and by extension, its precursor ACC) are well studied as stress response molecules, much less is known about the potentially vital role of auxins in regulating plant growth under conditions of low temperature stress., Conclusion: It is postulated that the interaction of all three hormones modulate crosstalk between various stress responses and recovery pathways to ameliorate the damage caused by freezing stress and enable plant survival. Given the dearth of information on phytohormones in cryobiology, more studies are needed to fully elucidate these relationships in the context of freezing stress caused by liquid nitrogen. Doi.org/10.54680/fr23610110612.

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.

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.

A previous study showed that foliar application of ethephon to litchi trees with mature shoots and dormant terminal buds during autumn successfully inhibited new vegetative shoot growth prior to floral induction thereby promoting carbohydrate accumulation and flowering. However, the functional mechanisms of ethylene, the breakdown product of ethephon, in the leaves and terminal buds of litchi and its involvement in the flowering process is largely unknown. Therefore, this study aimed to investigate the phenological, physiological and molecular changes underlying ethephon application and its associations with bud dormancy and flowering in litchi. Ethephon was applied as a single full canopy spray at a concentration of 1000 mg⋅L -1 to 'Mauritius' litchi trees with mature vegetative shoots and dormant terminal buds during late autumn of 2018 (mid-April; Southern Hemisphere). Untreated trees served as a control. Phenological characteristics, such as bud dormancy and panicle development, leaf chlorophyll (as an indicator of shoot maturity), ethylene evolution, gene expression levels of flowering- (LcFT2, LcFLC and LcAP1), dormancy- (LcSVP1 and LcSVP2) and ethylene pathway-related (LcEIN3) genes and non-structural carbohydrates were determined in terminal buds, leaves and/or shoots. Ethephon application induced bud dormancy, significantly delayed panicle emergence and promoted pure floral panicle development under more favorable inductive conditions. Ethylene evolution increased sharply 2 h after application in both leaves and terminal buds, but decreased rapidly thereafter in the leaves, while remaining high in terminal buds for seven days before gradually declining. Ethephon application significantly increased relative expression of LcEIN3 and LcFLC in terminal buds one day after application, while LcFT2 expression in leaves and LcAP1 expression in terminal buds were significantly increased at the bud break stage. Significant treatments differences were also observed for various carbohydrate metabolites in leaves and shoots at the bud break or floral initiation stage. Our study provided evidence that ethephon application plays an important role in the physiological and molecular regulation of bud dormancy of litchi. By influencing the time of bud break, ethephon application can be a useful tool to manage panicle emergence under less inductive conditions., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

One of the projected effects of climate change is a reduction in rainfall in certain regions of the world. Hence, the agricultural and livestock sectors will have to cope with increasing incidences of water shortage while still maintaining productivity levels to feed an ever increasing global population. This short communication reports on the effect of a 2-week water stress on Pelibuey sheep in Cuba. Three treatments were compared, viz. supply of water ad libitum, water supplied once every 3 or 6 days. Following exposure to the water stress, the results showed no changes in sheep body weight or rectal temperature. However, respiration frequency was affected with water stress causing a reduction from 23.3 to 13.3 respirations per min in control and water-deprived animals, respectively. Furthermore, there was evidence for hemoconcentration in response to water stress (levels of hemoglobin increased from 9.2 to 13.1 g L -1 and hematocrits from 27.6 to 39.3% in the control group and animals restricted to water once every 6 days. The imposed water stress was also evident in the reduction of lymphocytes (from ±63 to 43%), and in increase of neutrophils (from approximately 38 to 54%) and leukocytes (from 3133 to 4933 per mm 3 ). The results indicated a decline in the levels of antioxidants, i.e., SOD from approximately 13 to 10 U mg -1 protein and CAT activity from 23 to 9 U mg -1 protein. To the best of our knowledge, this is the first report on the response of Pelibuey sheep to short-term water shortage stress under Cuban environmental conditions., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

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 m 2 . 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.

Cryopreserved zygotic embryonic axes offer the best means of genetic diversity conservation of recalcitrant-seeded species, but frequently shoots fail to develop following processing for, and after, cryostorage. The present work offers a means to overcome this, by generating adventitious shoots from seedling roots produced after axis cryopreservation. Embryonic axes of Ekebergia capensis were exposed to cryoprotectants, flash dried, and rapidly cooled in nitrogen slush. Cryoprotection was an essential step, with both glycerol and DMSO permitting survival after cryogen exposure, but sucrose alone, or in combination with glycerol, was deleterious. Adventitious shoots were formed from seedling roots developed by axes germinated after cryogen exposure, after being subjected to intermittent flushing with a BAP-containing medium for 24 h in a temporary immersion system and subsequent culture on a semi-solid BAP-containing medium. After excision, a high proportion of the adventitious shoots produced roots in vitro, with most of these rooted plantlets being subsequently successfully acclimated.