Micropropagation of 4-year-old elite Eucalyptus tereticornis trees

Nanoparticles as a Tool for Alleviating Plant Stress: Mechanisms, Implications, and Challenges

Plants, being sessile, are continuously exposed to varietal environmental stressors, which consequently induce various bio-physiological changes in plants that hinder their growth and development. Oxidative stress is one of the undesirable consequences in plants triggered due to imbalance in their antioxidant defense system. Biochemical studies suggest that nanoparticles are known to affect the antioxidant system, photosynthesis, and DNA expression in plants. In addition, they are known to boost the capacity of antioxidant systems, thereby contributing to the tolerance of plants to oxidative stress. This review study attempts to present the overview of the role of nanoparticles in plant growth and development, especially emphasizing their role as antioxidants. Furthermore, the review delves into the intricate connections between nanoparticles and plant signaling pathways, highlighting their influence on gene expression and stress-responsive mechanisms. Finally, the implications of nanoparticle-assisted antioxidant strategies in sustainable agriculture, considering their potential to enhance crop yield, stress tolerance, and overall plant resilience, are discussed.

A Comprehensive Review Uncovering the Challenges and Advancements in the In Vitro Propagation of Eucalyptus Plantations

The genus Eucalyptus is a globally captivated source of hardwood and is well known for its medicinal uses. The hybrid and wild species of Eucalyptus are widely used as exotic plantations due to their renowned potential of adapting to various systems and sites, and rapid large-scale propagation of genetically similar plantlets, which further leads to the extensive propagation of this species. Tissue culture plays a crucial role in the preservation, propagation, and genetic improvement of Eucalyptus species. Despite unquestionable progression in biotechnological and tissue culture approaches, the productivity of plantations is still limited, often due to the low efficiency of clonal propagation from cuttings. The obtained F1 hybrids yield high biomass and high-quality low-cost raw material for large-scale production; however, the development of hybrid, clonal multiplication, proliferation, and post-developmental studies are still major concerns. This riveting review describes the problems concerning the in vitro and clonal propagation of Eucalyptus plantation and recent advances in biotechnological and tissue culture practices for massive and rapid micropropagation of Eucalyptus, and it highlights the Eucalyptus germplasm preservation techniques.

An efficient in vitro process for cyclic clonal production of shoots from adult tree of Cassia alata L. and evaluation of genetic stability using DNA-based markers

An efficient, cyclic, two-step protocol for clonal in vitro regeneration system of an antiallergenic plant, Cassia alata, has been successfully developed. Nodal explants from a 5-year-old tree were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations (1.0, 2.5, 5.0, 7.5, and 10.0 μM) of thidiazuron (TDZ). TDZ (5.0 μM) was found to be optimal for the formation of maximum shoot induction. Shoot proliferation and elongation increased when the regenerated shoots were subcultured on hormone-free MS medium after 4 weeks of exposure to TDZ. Nodal explants from in vitro regenerated microshoots to developed shoots, thus making the process recurrent. In 6 months duration, owing to the recurring nature of the protocol, large number of shoots could be produced from a single nodal explant from an adult tree. Shoots rooted best on MS supplemented medium with 0.5 μM IBA. Regenerated plantlets were acclimatized and successfully transplanted to the garden soil, where they grew well without any morphological and genetic variations. To confirm the uniformity, the genetic fidelity of in vitro raised C. alata clones was also assessed by using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers. The present regeneration process not only favored the clonal multiplication but also expressed the regeneration capability of in vitro regenerated microshoots and can be subjugated for catering enough raw materials to various pharma industries by continuous cyclic shoot production.

Plant regeneration through callus organogenesis and true-to-type conformity of plants by RAPD analysis in Desmodium gangeticum (Linn.) DC

An efficient plant regeneration protocol was established for an endangered ethnomedicinal plant Desmodium gangeticum (Linn.) DC. Morphogenic calli were produced from 96 % of the cultures comprising the immature leaf explants on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid (4.0 mg l(-1)) in combination with 6-benzylaminopurine (BA; 0.8 mg l(-1)). For callus regeneration, various concentrations of BA (1.0-5.0 mg l(-1)) or thidiazuron (TDZ; 1.0-5.0 mg l(-1)) alone or in combination with indole-3-acetic acid (IAA; 0.2-1.0 mg l(-1)) were used. Highest response of shoot regeneration was observed on MS medium fortified with TDZ (4.0 mg l(-1)) and IAA (0.5 mg l(-1)) combination. Here, 100 % cultures responded with an average number of 22.3 shoots per gram calli. Inclusion of indole-3-butyric acid in half MS medium favored rooting of recovered shoots. Out of 45 rooted plants transferred to soil, 40 survived. Total DNA was extracted from the leaves of the acclimatized plants of D. gangeticum. Analysis of random amplified polymorphic DNA using 13 arbitrary decanucleotide primers showed the genetic homogeneity in all the ten plants regenerated from callus with parental plant, suggesting that shoot regeneration from callus could be used for the true-to-type multiplication of this plant.

Large-scale in vitro multiplication of Crataeva nurvala

Conservation and propagation of species using biotechnologic tools-such as plant tissue culture-are relevant when natural propagation is hampered for various reasons. In vitro techniques allow mass multiplication and propagation under pathogen-free conditions but also override dependence on season for availability of plant material. Moreover, in vitro genetic manipulation of a species, invariably, requires a prestandardized tissue culture protocol for its multiplication.To fulfill these requirements, efficient, cyclic, two-step protocols for micropropagation of the medicinal tree-Crataeva nurvala-employing juvenile explants and those from mature trees, were developed. Both protocols can be employed at commercial scale. The seedling-derived explants (e.g., cotyledonary nodes, epicotyl nodes, hypocotyl segments, first pair of leaves, cotyledons, and root segments) developed shoots on Murashige and Skoog's (MS) or the same supplemented with different concentrations of 6-benzylaminopurine (BAP). The epicotyl and cotyledonary nodal explants developed shoots on MS basal medium. Other explants exhibited caulogenesis on BAP (0-2.0 mg/L) adjuvated media. The explants from in vitro regenerated shoots too exhibited a similar caulogenic capability. Nodal explants from a 30-yr-old-tree, when cultured on MS medium supplemented with 0.5 mg/L BAP, produced multiple shoots which elongated satisfactorily on the same medium. Similar to the microshoots developed from the seedling derived explants, nodal and leaf explants from the microshoots regenerated from the mature explants too developed shoots, thus making the process recurrent. Due to the recurrent nature of the protocol, over 5400 shoots may be produced from a single nodal explant of an adult tree over a period of six months. The addition of casein hydrolysate significantly increased the average number of shoots per explant. The regenerated shoots could be rooted on the medium supplemented with 0.02 mg/L or 0.1 mg/L NAA (alpha-naphthalene acetic acid). Regenerated plantlets were acclimatized and successfully transplanted to soil.

Micropropagation and germplasm conservation of Central Park Splendor Chinese elm (Ulmus parvifolia Jacq. 'A/Ross Central Park') trees

Micropropagation offers opportunities to propagate, preserve and ship tree germplasm. It also reduces the risk of moving pathogens and insects with the germplasm due to built-in pathogen detection capabilities of aseptic cultures. For the past few decades, our laboratory has been involved in a project to preserve and restore a large, cold hardy, and historically important Chinese elm (Ulmus parvifolia Jacq. 'A/Ross Central Park') tree. Here we present three simple and efficient systems for its micropropagation, germplasm conservation and distribution: (1) in vitro plant formation from meristematic nodules (MNs), (2) plantlet generation from axillary buds, and (3) in vitro rooting of micro-cuttings from 20-years-old hedged stock plants. Newly flushed nodal segments were used as explants. WPM with 0.5 mg/l BA was found to be the best medium for meristematic shoot development and WPM supplemented with 2.0 mg/l 4-CPPU and 0.5 mg/l TDZ was best for meristematic nodule formation. Rhizogenesis of regenerants and micro-cuttings was best achieved on WPM with 1.0 mg/l NAA and 2% sucrose. Rooted plants were readily acclimatized to the greenhouse ambient environment and continued to grow well under greenhouse conditions. The survival rate of acclimatized plantlets under ex vitro conditions was 100% after 4 weeks. Plants looked healthy with no visually detectable phenotypic variation based on observation of about 1,000 plants. Cycling of shoot explants and MNs through repetitive cultures was effective in scaling-up propagules.

An efficient, in vitro cyclic production of shoots from adult trees of Crataeva nurvala Buch. Ham

An efficient, cyclic, two-step protocol for micropropagation of medicinal tree, Crataeva nurvala has been successfully developed, which can be employed at a commercial scale. Nodal explants from 30-year-old tree when cultured on MS medium supplemented with 2.22 microM BAP produced multiple shoots, which elongated satisfactorily on the same medium. Nodal and leaf explants from in vitro regenerated microshoots too developed shoots, thus making the process recurrent. In 6-month duration, owing to the recurring nature of the protocol, over 5400 shoots could be produced from a single nodal explant from the adult tree. Addition of casein hydrolysate significantly increased the average number of shoots per explant. Maximum number of shoots regenerated on medium supplemented with 100 mg l(-1) casein hydrolysate. Shoots could be rooted on 1/2 MS supplemented with 0.11 and 0.54 microM NAA. Regenerated plantlets were acclimatized and successfully transplanted to soil.