Inoculation of endophytic bacteria on host and non-host plants--effects on plant growth and Ni uptake.

Thidiazuron (TDZ) has gained a considerable attention during past decades due to its efficient role in plant cell and tissue culture. Wide array of physiological responses were observed in response to TDZ-application in different plant species. TDZ has shown both auxin and cytokinin like effects, although, chemically, it is totally different from commonly used auxins and cytokinins. A number of biological (physiological and biochemical) events in cells are induced or enhanced by TDZ, but the mode of action of TDZ is yet unknown. However, varieties of underlying mechanisms were revealed by reports showing how morphogenic events were induced by application of TDZ. Other reports showed that TDZ may modify endogenous plant growth regulators, either directly or indirectly and produce reactions in cell/tissue, necessary for its division/regeneration. Other possibilities include modification in cell membrane, energy levels, nutrient absorption, transport and assimilation, etc. In this review, recent advancements in TDZ application in plant sciences are discussed.

	 

	Key words: Thidiazuron, plant growth regulators, somatic embryogenesis, regeneration, cell cultures, metabolism.

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Thidiazuron: A multi-dimensional plant growth regulator

Green synthesis by using biological agents has been a simple and effective approach for the synthesis of various forms of nanoparticles. The present investigation was intended to synthesis Ag-NPs and ZnO-NPs under photo-condition using the aqueous extracts of two mangrove plants namely Heritiera fomes and Sonneratia apetala and evaluate their potential biomedical applications. The formation of nanoparticles in aqueous solution of H. fomes and S. apetala under exposure to sun light was validated by change in color and formation of monodispersed NPs with a narrow particle size distribution. Fourier transform infrared spectroscopy (FT-IR) reveals the presence of Oxime and other heterocyclic compounds to be the most probable compounds responsible for the reduction and stability of nanoparticles in the solutions. The synthesized NPs displayed moderate free radical scavenging properties. The anti-inflammatory potential of ZnO-NPs was recorded to be comparatively higher than that of Ag-NP with 79% and 69.1% respectively. The Ag-NPs with unique properties of inhibiting α-amylase (91.14% and 89.16%) were found to be significantly high indicating its antidiabetic property. The synthesized NPs showed varied zone of inhibition (9-16mm) against the tested microbial pathogens. The synthesized nanoparticles possess strong biological activities in terms of antioxidant, anti-inflammatory, antidiabetic and antibacterial, potentials which could be utilized in various biological applications by the cosmetic, food and biomedical industries.

Photo-mediated green synthesis of silver and zinc oxide nanoparticles using aqueous extracts of two mangrove plant species, Heritiera fomes and Sonneratia apetala and investigation of their biomedical applications.

Genetic stability and phytochemical analysis of the in vitro regenerated plants of Dendrobium nobile Lindl., an endangered medicinal orchid

Rapid in vitro propagation of Dendrobium hybrids through direct shoot formation from foliar explants, and protocorm-like bodies

Efficient shoot regeneration of Vanda coerulea was achieved using thin shoot tip sections and thidiazuron Protocorm-like bodies or proliferating shoot buds was observed when thin shoot tip sections were cultured on Vacin and Went's (VW) (1949) basal medium supplemented with 1135 µM thidiazuron The highest percentage of protocorm-like bodies (95%) survived and ultimately produced healthy shoots with 2 – 3 leaves when subjected to a 4 week thidiazuron treatment A culture period longer than 8 weeks with thidiazuron resulted in the formation of fasciated or distorted shoots Shoots produced roots when cultured on half strength VW basal medium supplemented with 1142 µM IAA The well rooted shoots were transferred to pots containing charcoal chips, coconut husk and broken tiles (2:2:1) and a 98% survival rate was achieved

Efficient Regeneration of Vanda Coerulea, an Endangered Orchid Using Thidiazuron

The present investigation reports optimized parameters for somatic embryogenesis and cryopreservation of embryogenic cultures using shoot apical domes from mature trees of Pinus roxburghii Sarg. Embryogenic tissue of P. roxburghii Sarg. was cryopreserved for 24 h, 10 d, and 8 wk using sorbitol and dimethylsulfoxide (DMSO) as cryoprotectants. Results indicate that 0.2M sorbitol and 5% DMSO had the best cryoprotecting effect. The recovered tissue showed luxuriant growth on maintenance medium (II). Partial desiccation of thawed embryogenic tissue for 24 h prior to transfer to maturation medium enhanced the maturation of somatic embryos. Maturation frequency increased from 1.3 to 18.3% after 12 h desiccation treatment, and from 18.3 to 61.8% after 24 h of desiccation. However, non-desiccated embryogenic tissue produced the least number of somatic embryos (1.3%) on the maturation medium with the same abscisic acid and Gellan gum concentration. All the three embryogenic lines produced plantlets and had the same appearance and normal growth as compared to unfrozen controls.

Cryopreservation and plant regeneration via somatic embryogenesis using shoot apical domes of mature pinus roxburghii sarg. trees

This study highlights the induction of somatic embryogenesis using immature zygotic embryos of Carica papaya commercial varieties viz. Coorg Honey dew, Washington, Honey dew, Pusa delicious, Pusa nanha, Taiwan 786, Taiwan 785, Sunrise, Solo, Co-1, C0-7, and Co-3 respectively. Somatic embryos formed in the presence of thidiazuron (TDZ) in combination with 2, 4-dichlorophenoxy acetic acid (2, 4-D), but never on  explants cultured on control medium lacking plant growth regulators. Embryogenic callus could be induced from immature zygotic embryos after 4-6 weeks of culture on full-strength Murashige and Skoog inorganic salts, which served as the basal medium supplemented with 4.52 μM 2, 4-D and 2.27 μM TDZ (induction and maintenance medium). The ability to induce  embryogenic tissue varied for different papaya tested varieties, and there was a mixed genotypic response on the induction of embryogenic cultures. The highest percentage of somatic embryogenesis was noticed in a papaya variety Taiwan-786 (87.0±4.2a), followed by Taiwan- 785  (85.0±3.0a), and Coorg Honey dew (81.0±3.2a) respectively. This protocol is simple and reproducible, and could be useful for regenerating large number of plants as well as provide a target tissue for genetic  transformation experiments.

Induction of somatic embryogenesis in Papaya (Carica papaya)

Embryogenic cultures were initiated and established for the first time in 3 different genotypes of Pinus kesiya using mature zygotic embryos and triacontanol. Mature zygotic embryos produced white-mucilaginous embryogenic callus when cultured on half strength MSG (Becwar et al. 1990) basal medium supplemented with 90 mM maltose, 2.0 g l−1 Gellan gum, 9.0 M 2, 4-D and 10 g l−1triacontanol. On subculture of such embryogenic callus on the maintenance medium (II) containing 2.0 M 2,4-D and 2.0 g l−1 triacontanol induced cleavage polyembryogenesis with proembryos. The percentage of somatic embryogenesis was not similar in all the three genotypes. The highest percentage of somatic embryogenesis (88.5 %) was recorded in PK04 genotype. Somatic embryos were successfully germinated on half strength MSG basal medium without growth regulators. Somatic seedlings showed fast growth and a survival rate of 95%. This work for the first time reveals that triacontanol can be used as an effective growth regulator for inducing somatic embryogenesis in conifers.

Plant regeneration via somatic embryogenesis in Pinus kesiya (Rolye ex. Gord.) influenced by triacontanol

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K. Nataraja

Papers

Efficient Regeneration of Vanda Coerulea, an Endangered Orchid Using Thidiazuron

Cryopreservation and plant regeneration via somatic embryogenesis using shoot apical domes of mature pinus roxburghii sarg. trees

Induction of somatic embryogenesis in Papaya (Carica papaya)

Plant regeneration via somatic embryogenesis in Pinus kesiya (Rolye ex. Gord.) influenced by triacontanol

Plant Regeneration via Somatic Embryogenesis Using Secondary Needles of Mature Trees of Pinus roxburghii Sarg