A pulse treatment of sucrose at 0, 20, 40, 60, 80, 100, and 120gL(superscript (-1)) in combination with 8-hydrox-yquinoline sulfate (HQS) at 200 mg L(superscript (-1)) for 10h was evaluated daily for its effect on the vase life and flower quality of cut rose flowers. The pulse treatment of sucrose at above 80gL(superscript (-1)) produced a vase life of 6 to 7 days, while at below 80gL(superscript (-1)) vase life was maintained for 4 days on average. The pulse treatment of silver thiosulfate (STS) at 0.2mM for 2h or STS for 2h followed by sucrose at 120gL(superscript (-1)) supplemented with HQS for 10h extended the vase life of cut rose flowers to about 9 and 10 days, individually. On the other hand, a pulse treatment with sucrose or distilled water in combination with HQS maintained vase life for 7 and 3 days, respectively. Flower quality of specimens treated with STS followed by sucrose in combination with HQS was better than that of those treated with STS alone. Although visual quality could be maintained for up to 13 days in STS followed by sucrose in combination with HQS, flower quality decreased notably after 10 days. The ethylene production was greatest in untreated rose flowers (about 3h after harvest) and decreased after chemical solutions treatment. The inhibition of ethylene production was greater in sucrose in combination with HQS than with STS or STS followed by sucrose along with HQS, although the effectiveness of the latter for maintaining rose vase life was better than the former.

https://ejournal.sinica.edu.tw/bbas/content/2000/4/bot414-07.pdf

Postharvest life of cut rose flowers as affected by silver thiosulfate and sucrose

A regeneration system was developed for Prunus serotina from a juvenile (F) and two mature genotypes (#3 and #4). Adventitious shoots regenerated from leaves of in vitro cultures on woody plant medium with thidiazuron (TDZ) and naphthaleneacetic acid (NAA). The best regeneration for genotype F (91.4%) was observed on medium with 9.08 μM TDZ and 1.07 μM NAA. The highest mean number of shoots (8.2) was obtained on medium containing 9.08 μM TDZ and 0.54 μM NAA. Genotype #3 had the highest regeneration (41.7%) with a mean number of shoots (4.8) on 9.08 μM TDZ and 1.07 μM NAA, whereas genotype #4 had a 38.8% regeneration with a mean of 3.3 shoots. Genotype #4 had the highest mean number of shoots (4.8) on 4.54 μM TDZ and 1.07 μM NAA. Silver thiosulphate at 60 or 80 μM increased the percent regeneration of the mature genotypes #3 (75%) and #4 (58%). Adventious shoots were rooted (70–76%) and rooted plantlets survived after acclimatization to the greenhouse. The effect of kanamycin concentration on adventitious shoot regeneration was also evaluated.

https://www.nrs.fs.fed.us/pubs/jrnl/2008/nrs_2008_liu-x_001.pdf

Plant regeneration from in vitro leaves of mature black cherry ( Prunus serotina )

The conservation of crop genetic resources, including their wild relatives, is of utmost importance for the future of mankind. Most crops produce orthodox seeds and can, therefore, be stored in seed genebanks. However, this is not an option for crops and species that produce recalcitrant (non-storable) seeds such as cacao, coffee and avocado, for crops that do not produce seeds at all; therefore, they are inevitably vegetatively propagated such as bananas, or crops that are predominantly clonally propagated as their seeds are not true to type, such as potato, cassava and many fruit trees. Field, in vitro and cryopreserved collections provide an alternative in such cases. In this paper, an overview is given on how to manage and setup a field, in vitro and cryopreserved collections, as well as advantages and associated problems taking into account the practical, financial and safety issues in the long-term. In addition, the need for identification of unique accessions and elimination of duplicates is discussed. The different conservation methods are illustrated with practical examples and experiences from national and international genebanks. Finally, the importance of establishing safe and long-term conservation methods and associated backup possibilities is highlighted in the frame of the global COVID-19 pandemic.

Challenges and Prospects for the Conservation of Crop Genetic Resources in Field Genebanks, in In Vitro Collections and/or in Liquid Nitrogen.

Ancymidol was investigated as an alternative mediumsupplement to mannitol for slow-growth conservation ofpotato microplants in vitro. Differentconcentrations of ancymidol (0, 5, 10, 15, 20, 25, 30,35 and 40 μM) were tested in slow-growthmedia based on MS medium supplemented with either 30or 60 gl-1 sucrose. The cultures were conservedunder a 16-h photoperiod at two temperature regimesi.e. 24 ± 1 °C and 6 ± 1 °C. Therewere significant interactions between ancymidol andother factors such as sucrose, temperature andgenotype for microplant survival, microshoot heightand overall microplant growth. Ancymidol did have abeneficial effect on culture viability after prolongedmaintenance in vitro. The growth-inhibitingeffect of ancymidol persisted through a 16-monthculture period. Combined effect of ancymidol, sucroseand temperature showed that optimum culture viabilityand desirable microplant growth were obtained when thecultures were grown in MS medium supplemented with 10μM ancymidol plus 60 gl-1 sucrose at6 ± 1 °C. Vitrification and flaccidity, whichare very frequently observed in potato microplantcultures during prolonged maintenance in vitrounder osmotic stress (mannitol), were not observedwhen the microplants were conserved in ancymidolmedia. Genetic stability of potato microplantsconserved in ancymidol media was evaluated usingrandomly amplified polymorphic DNA (RAPD)fingerprints. Ancymidol did not induce any detectablegenetic variation in genomic DNA as visualized by theabsence of either any additional RAPD fragment oralterations in RAPD fragment patterns.

Slow-growth conservation of potato microplants: efficacy of ancymidol for long-term storage in vitro

Plant genetic resources for sustainable usage have been investigated as a basis for breeding programs for crop improvement and the advance of target gene(s) in genetic engineering. Ex situ conservation is used to preserve plant species manually in addition to in situ techniques. Orthodox seeds of temperate and subtropical species are mainly conserved as a genebank. However, methods of conservation of seedless and heterozygous orthodox tropical plant species and those with recalcitrant seeds are still limited. In vitro or live vegetative preservation is the preferred way to conserve elite species. There are many approaches to this, including short-, medium- and long-term preservation. Minimal growth in vitro culture or medium-term preservation has been widely exploited as a source of disease-free plants, which are promptly available for international material exchange. This technique is well established and is applied to a wide range of genetic conservation measures with high recovery growth and maintenance of genetic stability when compared to cryopreservation or longterm storage, identified by RAPD and AFLP genetic variation assay. Recently developed techniques and the application of minimal growth preservation will be described in this review. There are many techniques, which can be used to control the in vitro physical and chemical environments, including low temperature, low light intensity, short-photoperiod, high osmotic adjustment, low nutrient concentration and plant growth retardant supplementation for in vitro germplasm. In addition, the combination of both physical and chemical factors is a progressive channel, which can be used to develop general practices for medium-term preservation of tropical plant species.

/pdf/minimal-growth-in-vitro-culture-for-preservation-of-plant-20mpgp509w.pdf

Minimal Growth in Vitro Culture for Preservation of Plant Species

Efficacy of silver thiosulfate (STS) in reducing ethylene-induced culture abnormalities during minimal growth conservation of microplants was studied in seven potato (Solanum tuberosum L.) genotypes. Different concentrations of STS (0, 1.5, 3.0, 4.5, 6.0, 7.5 and 9.0 μg ml–1) were tested in minimal growth medium based on MS medium supplemented with 20 g l–1 mannitol and 40 g l–1 sucrose. STS improved the microplant growth and reduced the culture abnormalities during prolonged maintenance of potato shoot cultures in vitro. The beneficial effect of STS was most prominent for number of green leaves per microplant and leaf senescence. After 16 months of storage, desirable microplant growth was observed in cultures conserved in medium containing 6.0–9.0 μg ml–1 STS. The profile of the peroxidase isozymes of conserved cultures did not show any apparent genetic variation due to the presence of STS in the conservation medium.

S. K. Kaushik

Papers

Minimal growth conservation of potato microplants: silver thiosulfate reduces ethylene-induced growth abnormalities during prolonged storage in vitro