Integration of Nanotechnology in Plant Tissue Culture

: In the field of plant biology, tissue culture is having colossal applications, for example, the production of disease-free plants and their mass multiplication, germplasm preservation, genetic manipulation to get improved variety as well as the production of biologically active compounds. The integration of nanotechnology and application of nanoparticles (NPs) has shown a positive response in the elimination of microbial contaminants and induction of callus, somatic embryogenesis, organogenesis, production of secondary metabolites, and genetic transformation. This paper aims to highlight some of the recent advancements that came possible through the implementation of nanotechnology in the field of plant tissue culture and also discusses both positives and negatives aspects associated with NPs in plant tissue culture. The prospects through the involvement of recent innovations of nanotechnology such as dendrimers, quantum dots, and carbon nanotubes are also proposed.

Cryopreservation of 13 Commercial Cannabis sativa Genotypes Using In Vitro Nodal Explants

Cannabis has developed into a multi-billion-dollar industry that relies on clonal propagation of elite genetics with desirable agronomic and chemical phenotypes. While the goal of clonal propagation is to produce genetically uniform plants, somatic mutations can accumulate during growth and compromise long-term genetic fidelity. Cryopreservation is a process in which tissues are stored at cryogenic temperatures, halting cell division and metabolic processes to facilitate high fidelity germplasm preservation. In this study, a series of experiments were conducted to optimize various stages of cryopreservation and develop a protocol for long-term germplasm storage of Cannabis sativa. The resulting protocol uses a standard vitrification procedure to cryopreserve nodal explants from in vitro shoots as follows: nodes were cultured for 17 h in a pre-culture solution (PCS), followed by a 20-min treatment in a loading solution (LS), and a 60 min incubation in plant vitrification solution 2 (PVS2). The nodes were then flash frozen in liquid nitrogen, re-warmed in an unloading solution at 40 °C, and cultured on basal MS culture medium in the dark for 5 days followed by transfer to standard culture conditions. This protocol was tested across 13 genotypes to assess the genotypic variability. The protocol was successful across all 13 genotypes, but significant variation was observed in tissue survival (43.3–80%) and regrowth of shoots (26.7–66.7%). Plants grown from cryopreserved samples were morphologically and chemically similar to control plants for most major traits, but some differences were observed in the minor cannabinoid and terpene profiles. While further improvements are likely possible, this study provides a functional cryopreservation system that works across multiple commercial genotypes for long-term germplasm preservation.

Histology of maize seeds and young germinating embryos after liquid nitrogen exposure

Maize represents a staple food crop and is the second most important agricultural commodity globally. Considering the important role of maize for food security, the long-term conservation of valuable germplasm is critical to ensure that high levels of genetic diversity are available for breeding superior cultivars to face future challenges. Cryopreservation is regarded as the most appropriate tool for long-term germplasm preservation and has been investigated in different crops. This short communication adds to the existing knowledge on maize cryopreservation by describing histological changes observed in maize seeds and young germinating embryos after liquid nitrogen (LN) exposure. Plants were examined immediately after recovery from LN (day zero) and following 3 days of germination. At day 3, seeds exposed to LN showed lower germination rates than non-cryostored seeds, i.e., 60.7% vs. 83.3%. Histological evaluation at day 3 revealed that the thickness of the conical endosperm and the scutellum did not show any statistically significant differences between control and cryopreserved seeds. In contrast, for the other histological evaluations made, mostly regarding the thickness of mesocarp, mealy endosperm, plumule, radicle and the epidermis, significant differences were observed between control and cryostored seeds with the former consistently displaying higher average values than the latter.

The evaluation of java fine flavor cocoa propagation through somatic embryogenesis technique for germplasm preservation

Somatic embryogenesis is one of the newest technology that applied for the mass production of cocoa. This research aims to evaluate the regeneration rate of somatic embryos through somatic embryogenesis propagation techniques on java fine flavor cocoa. Cultivars in this study are ICCRI 01, ICCRI 02, DR 1, DR 2, DRC 16, DR 38, PNT 16, and PNT 30. Observations include parameters to determine the percentage of primary callus and embryogenic callus formation and the number of somatic embryos produced. Based on data, the ability of callus to produce primary embryos is highly dependent on plant cultivars and explant sources. Five cultivars showed a higher regeneration rate using explants from the petal part, while the rest showed a higher regeneration rate using explants from the staminode section. Embryogenic callus from each cacao cultivar has the same basic structure: a nodular friable structure consisting of many embryonic cells. Some fine flavor cacao cultivars that were able to produce callus and primary somatic embryos could not produce secondary somatic embryos and plantlets. However, two cultivars, which had low potential in producing primary embryos, had the high ability to produce secondary somatic embryos and develop into plantlets.

Stability analysis for seed longevity in landraces of sorghum [Sorghum bicolor (L.) Moench]

Seed longevity in sorghum is a major determinant in seed production and germplasm preservation. Forty-six local landraces representing nine genetic races of sorghum were evaluated under accelerated aging and natural storage conditions to study the genotype-environment interactions and the stability of landraces for seed longevity. Genotype-environment interactions were highly significant indicating the influence of storage conditions on seed longevity. The stability of landraces was estimated using mean (xi), regression coefficient (bi) and regression deviation (S2di). Environmental indices for the seed longevity traits were high in E1 (fresh seed) followed by E2 (accelerated aged seeds), E3 (stored seeds for 12 months) and E4 (stored seeds for 24 months). Seven sorghum landraces viz., IC-345729 (Bicolor), IC-347571 (Caudatum), IC-347577 (Durra), IC-345244 (Durra), IC-415803 (Durra), IC-415822 (Durra bicolor) and IC-415829 (Guinea bicolor) were stable for seed longevity. These genotypes are therefore, recommended for use in further breeding to improve seed longevity in sorghum, which otherwise is generally poor.

DIVERSITY OF PINEAPPLE GENETIC RESOURCES IN CUBA: THREATS AND ACTIONS FOR MINIMIZING LOSSES

Conservation of plant genetic resources (PGR) is essential to preserve diversity and to provide genes for plant breeding. This paper assesses the current status of pineapple PGR diversity in Cuba and actions are proposed to minimize the loss of diversity. In situ diversity was evaluated through field trips to different locations across the country, evidence was found that pineapple germplasm diversity is low. Only three (Spanish, Cayenne and Pernambuco) out of the five horticultural groups of this crop are presently planted at Cuba. Red Spanish is the predominant cultivar, and White Pineapple is an endangered one. The highest diversity was found at the Eastern region, where it was possible to find at least two different cultivars from each of these three groups. The ex situ pineapple collection contains 56 accessions, 45 % belong to the Spanish group, 20 % to Cayenne and 14 % to Pernambuco, while the rest are hybrids, improved cultivars and other related species. Threats of diversity loss were identified by the Research-Action-Participation method. Farmers and experts agreed that growing of the most common cultivars is being abandoned and consequently, there is high risk of loss of in situ diversity. Results document the low diversity of pineapple genetic resources in the country and the need to use in situ and ex situ conservation approaches as complementary strategies for germplasm preservation for future generations.