Hyphaene dichotoma (White) Furtado belongs to the Arecaceae family of and is a threatened species... more Hyphaene dichotoma (White) Furtado belongs to the Arecaceae family of and is a threatened species included in the IUCN red data list. In the present investigation, an attempt was made to germinate seeds of H. dichotoma. Successful seed germination was achieved in soil and sand mixture (1:1) when seeds were treated with 10% sulphuric acid for 24 h. This study will be helpful for further investigations on seed germination and conservation of H. dichotoma and related species.
The floral and extra floral nectaries are characteristic feature of the family Bignoniaceae. The ... more The floral and extra floral nectaries are characteristic feature of the family Bignoniaceae. The floral nectaries in Millingtonia hortensis (L.), Stenolobium stans (L.), Tabebuia pallida (Lindl.) and Tabebuia argentea (Britt.) observed as disk surrounding the base of the ovary. The time of secretion and positioning of anther in the opened flowers are conducive for cross pollination.
Clerodendrum pholomidis is an important medicinal plant of Lamiaceae. Leaves, internode and petio... more Clerodendrum pholomidis is an important medicinal plant of Lamiaceae. Leaves, internode and petiole explants were cultured on Murashige and Skoog (MS) medium supplemented with combinations of 2, 4-dichlorophenoxy acetic acid (2, 4-D), kinetin (kn) and indole-3 butyric acid (IBA). Leaf explants formed clusters of globular somatic embryos directly from epidermal cells within 12-15d when cultured on Murashige and Skoog (MS) medium supplemented with 2.00 mg/l 2,4-D, 0.50 mg/l Kn and 0.025 mg/l IBA. Somatic embryo germination successfully achieved on plant growth regulator (PGR) free 1⁄2 MS medium.
Hemidesmus indicus (L.) R. Br. ex Schult is commonly known as anantmul or Indian sarsaparilla. Th... more Hemidesmus indicus (L.) R. Br. ex Schult is commonly known as anantmul or Indian sarsaparilla. The roots of this plant, which display a wide range of medicinal, biological, and phytopharmaceutical properties, are used in the pharmaceutical and food industries. Conventionally, the plant is propagated by seed germination or vegetatively, but the efficacy of traditional methods has some limitations: plants derived from seed germination are prone to seed-borne diseases, or plantlet production using vegetative propagation is limited. In contrast, plant tissue culture allows for large-scale propagation and secondary metabolite production in vitro without sacrificing plants from their natural habitats. Many efforts have been made over 40 years of research to establish efficient micropropagation protocols to speed up cultivation of this plant, including callus-mediated in vitro propagation, somatic embryogenesis, and shoot multiplication using cotyledenory nodes, stem segments, shoot tips, and nodal explants. Among these explants, nodal explants are the most commonly used for H. indicus micropropagation. The application of adenine sulfate, citric acid, ascorbic acid, and arginine may be useful in preventing explant browning, premature leaf senescence, and shoot tip abscission during in vitro culture. This review provides insight into micropropagation, use of synthetic seeds for short-term germplasm preservation, and in vitro production of secondary metabolites such as 2-hydroxy-4-methoxybenzaldehyde, lupeol, vanillin, and rutin, from in vitro root and callus cultures. Furthermore, unexplored and possible innovative areas of research in Hemidesmus biotechnology are also discussed. • Hemidesmus indicus has multiple therapeutic applications. • H. indicus roots are used in confectionary and pharmacy. • This review comprehensively assesses H. indicus tissue culture. • Challenges and future research of H. indicus biotechnology are discussed.
Main conclusion Shoot tip necrosis is a physiological condition that negatively impacts the growt... more Main conclusion Shoot tip necrosis is a physiological condition that negatively impacts the growth and development of in vitro plant shoot cultures across a wide range of species. Abstract Shoot tip necrosis is a physiological condition and disorder that can arise in plantlets or shoots in vitro that results in death of the shoot tip. This condition, which can spread basipetally and affect the emergence of axillary shoots from buds lower down the stem, is due to the cessation of apical dominance. STN can occur at both shoot multiplication and rooting stages. One of the most common factors that cause STN is nutrient deficiency or imbalance. Moreover, the presence or absence of plant growth regulators (auxins or cytokinins) at specific developmental stages may impact STN. The cytokinin to auxin ratio within an in vitro plant can be modified by varying the concentration of cytokinins used in the culture medium. The supply of nutrients to in vitro shoots or plantlets might also affect t...
Oldenlandia herbacea (L.) Roxb. is an important medicinal plant of Indian, Malayan, and Chinese t... more Oldenlandia herbacea (L.) Roxb. is an important medicinal plant of Indian, Malayan, and Chinese traditional systems of medicines. In vitro flowering system serves as a model system to study flowering physiology, and role of combination of photoperiodic conditions and ethylene inhibitors. Ethylene is responsible for delayed flowering response in plants; hence, it is interesting to explore the role of ethylene inhibitors and photoperiod on flowering mechanism. The present study, for the first time, reports the influence of silver thiosulfate (STS), silver nitrate, and photoperiod (PP) to induce high-frequency in vitro flowering in O. herbacea. The flowers were induced from the in vitro shoots (2.0 floral buds per shoot) on MS medium containing 4 μM 6-benzylaminopurine + 2 μM indole-3-acetic acid + 5 μM STS at 14-h PP. This study could be the foundation to understand the role of PP and silver ions on flowering physiology at molecular level.
Hedyotis biflora (Linn.) Lam is an important herb, used in the Indian and Chinese traditional sys... more Hedyotis biflora (Linn.) Lam is an important herb, used in the Indian and Chinese traditional systems of medicines. Indiscriminate harvesting of this plant resulted in decline of its population from the natural habitats. The present study reports effective micropropagation and in vitro flowering in H. biflora. Healthy plants were maintained in the greenhouse to collect fresh explants (nodal segments). Average 3.2 shoot bud/node with 88% shoot regeneration obtained on Murashige and Skoog’s (MS) medium with 2.0 mg L−1 6-benzylaminopurine (BAP) and additives like 50 mg L−1 of ascorbic acid and 25 mg L−1 each of arginine, adenine sulphate and citric acid. About 84.5 shoots, with 8.1 cm shoot length were obtained on MS basal medium supplemented with 1.0 mg L−1 BAP, 0.5 mg L−1 kinetin (Kin) and 0.1 mg L−1 indole-3 acetic acid (IAA) and additives. In vitro flowers were induced in 91% cultures (6.8 flowers per shoot) when the shoots were cultured on MS medium supplemented with 1.5 mg L−1 BAP and 0.1 mg L−1 IAA at 12-h photoperiods. In vitro raised shoots were rooted with the help of indole-3 butyric acid (IBA) via in vitro and ex vitro techniques. The micropropagated plants were acclimatized with 91% survival rate in the field. Upon transfer of plantlets from the in vitro to ex vitro environments, there were significant changes in stomata, vein-islets and raphids. These micro-morphological changes may help micropropagated plantlets to establish under the field conditions. The present protocol is suitable for large scale micropropagation, conservation and commercial production of this plant. The protocol of in vitro flowering could be useful in understanding the in vitro pollination biology of H. biflora.
Crataeva nurvala (Buch Ham) is a medicinally important tree. The root and stem bark of the tree a... more Crataeva nurvala (Buch Ham) is a medicinally important tree. The root and stem bark of the tree are the main ingredients of various pharmaceutical products. The use of natural propagation strategies for C. nurvala has proven difficult. In this study, callus cultures were established from leaflets, petal, petiole, internodes and nodes on Murashige and Skoog’s (MS) medium supplemented with 2 mg L−1 of 2,4-dichlorophenoxyacetic acid and 0.4 mg L−1 kinetin. Transfer of calli on MS supplemented with 0.1-0.5 mg L−1 of kinetin, N6-benzyl adenine, or thidiazuron or N6-(2-isopentenyl) adenine resulted in root and shoot bud differentiation and somatic embryogenesis. In vitro regenerated shoots were successfully rooted on half-strength MS medium containing 0.5 mg L−1 α- naphthalene acetic acid. Somatic embryos continued their differentiation and maturation and converted into plantlets on medium without plant growth regulators. The regeneration response, the type of morphogenesis, varied with callus source and plant growth regulators. Micropropagated plantlets of C. nurvala successfully acclimatized in natural condition.
The Indian kino tree (Pterocarpus marsupium Roxb., Fabaceae) is listed in the IUCN red data list ... more The Indian kino tree (Pterocarpus marsupium Roxb., Fabaceae) is listed in the IUCN red data list as a direct result of the excessive exploitation of its wood. Biotechnology has provided feasible and effective solutions for the tissue culture and mass micropropagation of P. marsupium, thus serving as a means to conserve important germplasm. The synthesis of information in this review aims to stimulate further research on P. marsupium. Breeding and biotechnological programmes that mass produce and effectively manage P. marsupium germplasm in vitro are required, using synthetic seed technology, cryopreservation and in situ conservation to manage this important wood germplasm. Molecular markers have been used to a limited extent to confirm the genetic stability of in vitro-propagated material. Biotechnological advances for this leguminous tree of commercial importance would benefit from research involving photoautotrophic micropropagation for improved rooting, bioreactors for the production of somatic embryos and secondary metabolites, thin cell layers for enhanced micropropagation, and cryoconservation including of synthetic seeds.
Sandalwood spike disease (SSD) is likely to be the most destructive of known diseases to infect I... more Sandalwood spike disease (SSD) is likely to be the most destructive of known diseases to infect Indian sandalwood, Santalum album L., which is valued for its wood and scented essential oil derived from the heartwood. Even though the history of research on SSD extends for well over a century, most of the earlier work was primarily descriptive in macromorphological aspects. In 1969, a breakthrough was achieved by three independent research groups that confirmed the causal agent of SSD to be a phytoplasma. Despite this discovery, the identity of the causal agent was only confirmed by a single group using RFLP analysis and nested PCR of 16S rDNA. The phytoplasma that was identified showed high sequence similarity to aster yellows subgroup 16SrI-B. Tissue culture to derive disease-free clones and transgenic strategies to derive disease-resistant trees may be the only realistic solutions for ridding the limited S. album forests of SSD. This brief synthesis aims to stimulate greater interest in SSD, especially since sandalwood production has expanded to the Chinese mainland and to Australia.
Vitex is a large genus consisting of 230 species of trees and shrubs with multiple (ornamental , ... more Vitex is a large genus consisting of 230 species of trees and shrubs with multiple (ornamental , ethnobotanic and pharmacological) uses. Despite this, micropropagation has only been used to effectively propagate and preserve germplasm a limited number (six) of Vitex species (V. agnus-castus, V. doniana, V. glabrata, V. negundo, V. rotundifolia, V. trifolia). This review on Vitex provides details of published micropropagation protocols and perspectives on their application to germplasm preservation and in vitro conservation. Such details serve as a practically useful user manual for Vitex researchers. The importance of micropropagation and its application to synthetic seed production, in vitro flowering, production of secondary metabolites, and the use of molecular markers to detect somaclonal variation in vitro, are also highlighted.
African sandalwood or East African sandalwood (Osyris lanceolata Hochst. & Steud.; Santalaceae), ... more African sandalwood or East African sandalwood (Osyris lanceolata Hochst. & Steud.; Santalaceae), also known as Nepalese sandalwood (Osyris wightiana var. rotundifolia P.C. Tam), is a hemi-parasitic tree known for its fragrant wood. The essential oil is extracted from the root bark for the perfume industry and different parts of the tree have various medicinal uses. African sandalwood contains an array of phytochemicals such as dihydro-β-agarofuran polyesters, agarofuranases, polyesters, other sesquiterpenes and bisabolanes. This mini-review focuses on the general biology, traditional uses, phytochemical properties, propagation for conservation, and hemiparasitism of O. lanceolata.
MAIN CONCLUSION: Sustainable resource preservation of Santalum species that yield commercially im... more MAIN CONCLUSION: Sustainable resource preservation of Santalum species that yield commercially important forest products is needed. This review provides an understanding of their basic biology, propagation, hemi-parasitic nature, reproductive biology, and biotechnology. Many species of the genus Santalum (Santalaceae) have been exploited unremittingly for centuries, resulting in the extinction of one and the threatened status of three other species. This reduction in biodiversity of sandalwood has resulted from the commercial exploitation of its oil-rich fragrant heartwood. In a bid to conserve the remaining germplasm, biotechnology provides a feasible, and effective, means of propagating members of this genus. This review provides a detailed understanding of the biological mechanisms underlying the success or failure of traditional propagation, including a synopsis of the process of hemi-parasitism in S. album, and of the suitability of host plants to sustain the growth of seedlings and plants under forestry production. For the mass production of economically important metabolites, and to improve uniformity of essential oils, the use of clonal material of similar genetic background for cultivation is important. This review summarizes traditional methods of sandalwood production with complementary and more advanced in vitro technologies to provide a basis for researchers, conservationists and industry to implement sustainable programs of research and development for this revered genus.
Clerodendrum phlomidis L. f. is an important medicinal plant of the Lamiaceae family, particularl... more Clerodendrum phlomidis L. f. is an important medicinal plant of the Lamiaceae family, particularly its roots, which are used for various therapeutic purposes in a pulverized form. The objective of this study was to develop a standard protocol for axillary shoot proliferation and rooting of C. phlomidis for its prop- agation and conservation. Nodal explants were inoculated on Murashige and Skoog (MS) medium that was supplemented with one of six cytokinins: 6-benzyladenine, kinetin, thidiazuron, N6-(2-isopentenyl) adenine (2iP), trans-zeatin (Zea) and meta-topolin. Callus induction, which was prolific at all concentrations, formed at the base of nodal explants and hindered shoot multiplication and elongation. To avoid or reduce callus formation with the objective of increasing shoot formation, the same six cytokinins were combined with 4 µM 2,3,5-tri-iodobenzoic acid (TIBA) alone or in combination with 270 µM adenine sulphate (AdS). Nodal explants that were cultured on the medium supplemented with 9.12 µM Zea, 4 µM TIBA and 270 µM AdS produced significantly more and longer shoots than on medium without TIBA and AdS. Half-strength MS medium supplemented with 8.05 µM α-naphthaleneacetic acid was the best medium for root formation. Most (75%) in vitro rooted plantlets were successfully acclimatized under natural conditions.
Species within the Clerodendrum genus possess well-established pharmacological and medicinal prop... more Species within the Clerodendrum genus possess well-established pharmacological and medicinal properties. These emanate from the presence of many unique bioactive secondary metabolites. Eight Clerodendrum species (C. anomalum, C. calcicola, C. denticulatum, C. galeatum, C. leucophloeum, C. lutambense, C. eupatorioides, and C. aculeatum) are listed on the International Union of Conservation of Nature Red Data List. Micropropagation offers an opportunity for the conservation and large-scale propagation of elite genotypes and is a widely used technique for the conservation of threatened medicinal plants, including Clerodendrum species. This review highlights the advances that have been made thus far in the in vitro tissue culture of members of the Clerodendrum genus. Most of the efforts made to date have focussed on basic in vitro growth or regeneration, primarily from seeds, nodes, and leaves, either from an ex vitro or an in vitro source. Following a wide range of disinfection procedures that depend on the source and age of the explant, most studies employed Murashige and Skoog basal medium in a 12- to 16-h photoperiod. The most effective cytokinin for the induction of shoots was N 6-benzyladenine. Although plantlet acclimatization to field conditions was widely reported, it was often poorly quantified. Based on this base of information, applied aspects such as genetic engineering, mutation breeding, the production of haploid and double-haploid lines, protoplast fusion, embryo rescue, in vitro production of secondary metabolite acquisition through hairy roots or bioreactors, somaclonal variation, and cryopreservation still need to be developed and explored.
Crataeva L., an important genus of the Capparidaceae family, consists of medium-sized deciduous t... more Crataeva L., an important genus of the Capparidaceae family, consists of medium-sized deciduous trees used in various medicinal systems. The attractive flowers also make it a novel ornamental tree for gardening and landscaping. In vitro propagation strategies are useful for large-scale propagation and standardization of plant material and, once an effective tissue culture system has been established, can be used for long-term preservation of important germplasm through cryopreservation. This review provides up-to-date information on micropropagation studies of Crataeva species and perspectives for their conservation
Hyphaene dichotoma (White) Furtado belongs to the Arecaceae family of and is a threatened species... more Hyphaene dichotoma (White) Furtado belongs to the Arecaceae family of and is a threatened species included in the IUCN red data list. In the present investigation, an attempt was made to germinate seeds of H. dichotoma. Successful seed germination was achieved in soil and sand mixture (1:1) when seeds were treated with 10% sulphuric acid for 24 h. This study will be helpful for further investigations on seed germination and conservation of H. dichotoma and related species.
The floral and extra floral nectaries are characteristic feature of the family Bignoniaceae. The ... more The floral and extra floral nectaries are characteristic feature of the family Bignoniaceae. The floral nectaries in Millingtonia hortensis (L.), Stenolobium stans (L.), Tabebuia pallida (Lindl.) and Tabebuia argentea (Britt.) observed as disk surrounding the base of the ovary. The time of secretion and positioning of anther in the opened flowers are conducive for cross pollination.
Clerodendrum pholomidis is an important medicinal plant of Lamiaceae. Leaves, internode and petio... more Clerodendrum pholomidis is an important medicinal plant of Lamiaceae. Leaves, internode and petiole explants were cultured on Murashige and Skoog (MS) medium supplemented with combinations of 2, 4-dichlorophenoxy acetic acid (2, 4-D), kinetin (kn) and indole-3 butyric acid (IBA). Leaf explants formed clusters of globular somatic embryos directly from epidermal cells within 12-15d when cultured on Murashige and Skoog (MS) medium supplemented with 2.00 mg/l 2,4-D, 0.50 mg/l Kn and 0.025 mg/l IBA. Somatic embryo germination successfully achieved on plant growth regulator (PGR) free 1⁄2 MS medium.
Hemidesmus indicus (L.) R. Br. ex Schult is commonly known as anantmul or Indian sarsaparilla. Th... more Hemidesmus indicus (L.) R. Br. ex Schult is commonly known as anantmul or Indian sarsaparilla. The roots of this plant, which display a wide range of medicinal, biological, and phytopharmaceutical properties, are used in the pharmaceutical and food industries. Conventionally, the plant is propagated by seed germination or vegetatively, but the efficacy of traditional methods has some limitations: plants derived from seed germination are prone to seed-borne diseases, or plantlet production using vegetative propagation is limited. In contrast, plant tissue culture allows for large-scale propagation and secondary metabolite production in vitro without sacrificing plants from their natural habitats. Many efforts have been made over 40 years of research to establish efficient micropropagation protocols to speed up cultivation of this plant, including callus-mediated in vitro propagation, somatic embryogenesis, and shoot multiplication using cotyledenory nodes, stem segments, shoot tips, and nodal explants. Among these explants, nodal explants are the most commonly used for H. indicus micropropagation. The application of adenine sulfate, citric acid, ascorbic acid, and arginine may be useful in preventing explant browning, premature leaf senescence, and shoot tip abscission during in vitro culture. This review provides insight into micropropagation, use of synthetic seeds for short-term germplasm preservation, and in vitro production of secondary metabolites such as 2-hydroxy-4-methoxybenzaldehyde, lupeol, vanillin, and rutin, from in vitro root and callus cultures. Furthermore, unexplored and possible innovative areas of research in Hemidesmus biotechnology are also discussed. • Hemidesmus indicus has multiple therapeutic applications. • H. indicus roots are used in confectionary and pharmacy. • This review comprehensively assesses H. indicus tissue culture. • Challenges and future research of H. indicus biotechnology are discussed.
Main conclusion Shoot tip necrosis is a physiological condition that negatively impacts the growt... more Main conclusion Shoot tip necrosis is a physiological condition that negatively impacts the growth and development of in vitro plant shoot cultures across a wide range of species. Abstract Shoot tip necrosis is a physiological condition and disorder that can arise in plantlets or shoots in vitro that results in death of the shoot tip. This condition, which can spread basipetally and affect the emergence of axillary shoots from buds lower down the stem, is due to the cessation of apical dominance. STN can occur at both shoot multiplication and rooting stages. One of the most common factors that cause STN is nutrient deficiency or imbalance. Moreover, the presence or absence of plant growth regulators (auxins or cytokinins) at specific developmental stages may impact STN. The cytokinin to auxin ratio within an in vitro plant can be modified by varying the concentration of cytokinins used in the culture medium. The supply of nutrients to in vitro shoots or plantlets might also affect t...
Oldenlandia herbacea (L.) Roxb. is an important medicinal plant of Indian, Malayan, and Chinese t... more Oldenlandia herbacea (L.) Roxb. is an important medicinal plant of Indian, Malayan, and Chinese traditional systems of medicines. In vitro flowering system serves as a model system to study flowering physiology, and role of combination of photoperiodic conditions and ethylene inhibitors. Ethylene is responsible for delayed flowering response in plants; hence, it is interesting to explore the role of ethylene inhibitors and photoperiod on flowering mechanism. The present study, for the first time, reports the influence of silver thiosulfate (STS), silver nitrate, and photoperiod (PP) to induce high-frequency in vitro flowering in O. herbacea. The flowers were induced from the in vitro shoots (2.0 floral buds per shoot) on MS medium containing 4 μM 6-benzylaminopurine + 2 μM indole-3-acetic acid + 5 μM STS at 14-h PP. This study could be the foundation to understand the role of PP and silver ions on flowering physiology at molecular level.
Hedyotis biflora (Linn.) Lam is an important herb, used in the Indian and Chinese traditional sys... more Hedyotis biflora (Linn.) Lam is an important herb, used in the Indian and Chinese traditional systems of medicines. Indiscriminate harvesting of this plant resulted in decline of its population from the natural habitats. The present study reports effective micropropagation and in vitro flowering in H. biflora. Healthy plants were maintained in the greenhouse to collect fresh explants (nodal segments). Average 3.2 shoot bud/node with 88% shoot regeneration obtained on Murashige and Skoog’s (MS) medium with 2.0 mg L−1 6-benzylaminopurine (BAP) and additives like 50 mg L−1 of ascorbic acid and 25 mg L−1 each of arginine, adenine sulphate and citric acid. About 84.5 shoots, with 8.1 cm shoot length were obtained on MS basal medium supplemented with 1.0 mg L−1 BAP, 0.5 mg L−1 kinetin (Kin) and 0.1 mg L−1 indole-3 acetic acid (IAA) and additives. In vitro flowers were induced in 91% cultures (6.8 flowers per shoot) when the shoots were cultured on MS medium supplemented with 1.5 mg L−1 BAP and 0.1 mg L−1 IAA at 12-h photoperiods. In vitro raised shoots were rooted with the help of indole-3 butyric acid (IBA) via in vitro and ex vitro techniques. The micropropagated plants were acclimatized with 91% survival rate in the field. Upon transfer of plantlets from the in vitro to ex vitro environments, there were significant changes in stomata, vein-islets and raphids. These micro-morphological changes may help micropropagated plantlets to establish under the field conditions. The present protocol is suitable for large scale micropropagation, conservation and commercial production of this plant. The protocol of in vitro flowering could be useful in understanding the in vitro pollination biology of H. biflora.
Crataeva nurvala (Buch Ham) is a medicinally important tree. The root and stem bark of the tree a... more Crataeva nurvala (Buch Ham) is a medicinally important tree. The root and stem bark of the tree are the main ingredients of various pharmaceutical products. The use of natural propagation strategies for C. nurvala has proven difficult. In this study, callus cultures were established from leaflets, petal, petiole, internodes and nodes on Murashige and Skoog’s (MS) medium supplemented with 2 mg L−1 of 2,4-dichlorophenoxyacetic acid and 0.4 mg L−1 kinetin. Transfer of calli on MS supplemented with 0.1-0.5 mg L−1 of kinetin, N6-benzyl adenine, or thidiazuron or N6-(2-isopentenyl) adenine resulted in root and shoot bud differentiation and somatic embryogenesis. In vitro regenerated shoots were successfully rooted on half-strength MS medium containing 0.5 mg L−1 α- naphthalene acetic acid. Somatic embryos continued their differentiation and maturation and converted into plantlets on medium without plant growth regulators. The regeneration response, the type of morphogenesis, varied with callus source and plant growth regulators. Micropropagated plantlets of C. nurvala successfully acclimatized in natural condition.
The Indian kino tree (Pterocarpus marsupium Roxb., Fabaceae) is listed in the IUCN red data list ... more The Indian kino tree (Pterocarpus marsupium Roxb., Fabaceae) is listed in the IUCN red data list as a direct result of the excessive exploitation of its wood. Biotechnology has provided feasible and effective solutions for the tissue culture and mass micropropagation of P. marsupium, thus serving as a means to conserve important germplasm. The synthesis of information in this review aims to stimulate further research on P. marsupium. Breeding and biotechnological programmes that mass produce and effectively manage P. marsupium germplasm in vitro are required, using synthetic seed technology, cryopreservation and in situ conservation to manage this important wood germplasm. Molecular markers have been used to a limited extent to confirm the genetic stability of in vitro-propagated material. Biotechnological advances for this leguminous tree of commercial importance would benefit from research involving photoautotrophic micropropagation for improved rooting, bioreactors for the production of somatic embryos and secondary metabolites, thin cell layers for enhanced micropropagation, and cryoconservation including of synthetic seeds.
Sandalwood spike disease (SSD) is likely to be the most destructive of known diseases to infect I... more Sandalwood spike disease (SSD) is likely to be the most destructive of known diseases to infect Indian sandalwood, Santalum album L., which is valued for its wood and scented essential oil derived from the heartwood. Even though the history of research on SSD extends for well over a century, most of the earlier work was primarily descriptive in macromorphological aspects. In 1969, a breakthrough was achieved by three independent research groups that confirmed the causal agent of SSD to be a phytoplasma. Despite this discovery, the identity of the causal agent was only confirmed by a single group using RFLP analysis and nested PCR of 16S rDNA. The phytoplasma that was identified showed high sequence similarity to aster yellows subgroup 16SrI-B. Tissue culture to derive disease-free clones and transgenic strategies to derive disease-resistant trees may be the only realistic solutions for ridding the limited S. album forests of SSD. This brief synthesis aims to stimulate greater interest in SSD, especially since sandalwood production has expanded to the Chinese mainland and to Australia.
Vitex is a large genus consisting of 230 species of trees and shrubs with multiple (ornamental , ... more Vitex is a large genus consisting of 230 species of trees and shrubs with multiple (ornamental , ethnobotanic and pharmacological) uses. Despite this, micropropagation has only been used to effectively propagate and preserve germplasm a limited number (six) of Vitex species (V. agnus-castus, V. doniana, V. glabrata, V. negundo, V. rotundifolia, V. trifolia). This review on Vitex provides details of published micropropagation protocols and perspectives on their application to germplasm preservation and in vitro conservation. Such details serve as a practically useful user manual for Vitex researchers. The importance of micropropagation and its application to synthetic seed production, in vitro flowering, production of secondary metabolites, and the use of molecular markers to detect somaclonal variation in vitro, are also highlighted.
African sandalwood or East African sandalwood (Osyris lanceolata Hochst. & Steud.; Santalaceae), ... more African sandalwood or East African sandalwood (Osyris lanceolata Hochst. & Steud.; Santalaceae), also known as Nepalese sandalwood (Osyris wightiana var. rotundifolia P.C. Tam), is a hemi-parasitic tree known for its fragrant wood. The essential oil is extracted from the root bark for the perfume industry and different parts of the tree have various medicinal uses. African sandalwood contains an array of phytochemicals such as dihydro-β-agarofuran polyesters, agarofuranases, polyesters, other sesquiterpenes and bisabolanes. This mini-review focuses on the general biology, traditional uses, phytochemical properties, propagation for conservation, and hemiparasitism of O. lanceolata.
MAIN CONCLUSION: Sustainable resource preservation of Santalum species that yield commercially im... more MAIN CONCLUSION: Sustainable resource preservation of Santalum species that yield commercially important forest products is needed. This review provides an understanding of their basic biology, propagation, hemi-parasitic nature, reproductive biology, and biotechnology. Many species of the genus Santalum (Santalaceae) have been exploited unremittingly for centuries, resulting in the extinction of one and the threatened status of three other species. This reduction in biodiversity of sandalwood has resulted from the commercial exploitation of its oil-rich fragrant heartwood. In a bid to conserve the remaining germplasm, biotechnology provides a feasible, and effective, means of propagating members of this genus. This review provides a detailed understanding of the biological mechanisms underlying the success or failure of traditional propagation, including a synopsis of the process of hemi-parasitism in S. album, and of the suitability of host plants to sustain the growth of seedlings and plants under forestry production. For the mass production of economically important metabolites, and to improve uniformity of essential oils, the use of clonal material of similar genetic background for cultivation is important. This review summarizes traditional methods of sandalwood production with complementary and more advanced in vitro technologies to provide a basis for researchers, conservationists and industry to implement sustainable programs of research and development for this revered genus.
Clerodendrum phlomidis L. f. is an important medicinal plant of the Lamiaceae family, particularl... more Clerodendrum phlomidis L. f. is an important medicinal plant of the Lamiaceae family, particularly its roots, which are used for various therapeutic purposes in a pulverized form. The objective of this study was to develop a standard protocol for axillary shoot proliferation and rooting of C. phlomidis for its prop- agation and conservation. Nodal explants were inoculated on Murashige and Skoog (MS) medium that was supplemented with one of six cytokinins: 6-benzyladenine, kinetin, thidiazuron, N6-(2-isopentenyl) adenine (2iP), trans-zeatin (Zea) and meta-topolin. Callus induction, which was prolific at all concentrations, formed at the base of nodal explants and hindered shoot multiplication and elongation. To avoid or reduce callus formation with the objective of increasing shoot formation, the same six cytokinins were combined with 4 µM 2,3,5-tri-iodobenzoic acid (TIBA) alone or in combination with 270 µM adenine sulphate (AdS). Nodal explants that were cultured on the medium supplemented with 9.12 µM Zea, 4 µM TIBA and 270 µM AdS produced significantly more and longer shoots than on medium without TIBA and AdS. Half-strength MS medium supplemented with 8.05 µM α-naphthaleneacetic acid was the best medium for root formation. Most (75%) in vitro rooted plantlets were successfully acclimatized under natural conditions.
Species within the Clerodendrum genus possess well-established pharmacological and medicinal prop... more Species within the Clerodendrum genus possess well-established pharmacological and medicinal properties. These emanate from the presence of many unique bioactive secondary metabolites. Eight Clerodendrum species (C. anomalum, C. calcicola, C. denticulatum, C. galeatum, C. leucophloeum, C. lutambense, C. eupatorioides, and C. aculeatum) are listed on the International Union of Conservation of Nature Red Data List. Micropropagation offers an opportunity for the conservation and large-scale propagation of elite genotypes and is a widely used technique for the conservation of threatened medicinal plants, including Clerodendrum species. This review highlights the advances that have been made thus far in the in vitro tissue culture of members of the Clerodendrum genus. Most of the efforts made to date have focussed on basic in vitro growth or regeneration, primarily from seeds, nodes, and leaves, either from an ex vitro or an in vitro source. Following a wide range of disinfection procedures that depend on the source and age of the explant, most studies employed Murashige and Skoog basal medium in a 12- to 16-h photoperiod. The most effective cytokinin for the induction of shoots was N 6-benzyladenine. Although plantlet acclimatization to field conditions was widely reported, it was often poorly quantified. Based on this base of information, applied aspects such as genetic engineering, mutation breeding, the production of haploid and double-haploid lines, protoplast fusion, embryo rescue, in vitro production of secondary metabolite acquisition through hairy roots or bioreactors, somaclonal variation, and cryopreservation still need to be developed and explored.
Crataeva L., an important genus of the Capparidaceae family, consists of medium-sized deciduous t... more Crataeva L., an important genus of the Capparidaceae family, consists of medium-sized deciduous trees used in various medicinal systems. The attractive flowers also make it a novel ornamental tree for gardening and landscaping. In vitro propagation strategies are useful for large-scale propagation and standardization of plant material and, once an effective tissue culture system has been established, can be used for long-term preservation of important germplasm through cryopreservation. This review provides up-to-date information on micropropagation studies of Crataeva species and perspectives for their conservation
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Papers by Dr. Mafatlal M Kher