P. N. Krishnan

Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Tiruvananantapuram, Kerala, India

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Publications (23)15.6 Total impact

  • Third Indian Biodiversity Congress, SRM University, Chennai, India; 12/2014
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    ABSTRACT: A rapid in vitro propagation protocol for large-scale cultivation of Lagerstroemia speciosa L., an important medicinal and ornamental tree was established using nodal explants in Schenk and Hildebrandt (SH) medium optimized with various concentration and combinations of auxins and cytokinins. The study revealed, for the first time, accumulation of corosolic acid (CRA), an anti-diabetic and anti-obese pentacyclic triterpene in the in vitro plantlets. Multiple shoot induction was maximum in SH medium supplemented with 4.44 µM Benzyl Amino Purine (BAP) and shoot initials, when transferred to SH medium supplemented with 2.22 µM BAP, resulted in shoot multiplication and elongation. Rooted plantlets, after 2 weeks of hardening in mist-house and 3 months of rearing under shade-net, transferred to forest segments showed successful establishment (100 %). In a short duration of 24 weeks, ~2,450 hardened plantlets were obtained from a single nodal explant. The ISSR banding profiles of the regenerants and the mother plant were highly monomorphic and similarity matrix (0.96–0.99) confirmed genetic fidelity of the clones. Chemical analysis using HPLC showed that CRA content is more in mature (0.012–0.062 % DW) than young leaves (0.004–0.007 % DW) of the in vitro derived plantlets. The differential synthesis of CRA in micropropagated and mother plant was studied using gene expression profiles. The expression of upstream rate limiting genes in terpenoid biosynthesis was relatively high in young leaves while downstream Cytochrome P450 hydroxylase (CYP450H), catalyzing the final step(s) in CRA synthesis, was more in mature leaf, suggesting a strong correlation between observed CRA variation and gene expression. The study signifies the role of in vitro methodology for true-to-type regeneration and its possible utility for biosynthesis of CRA, throughout the year.
    Plant Cell Tissue and Organ Culture 12/2014; 120(3). DOI:10.1007/s11240-014-0665-3 · 2.61 Impact Factor
  • T.S Preetha · A.S. Hemanthakumar · P.Padmesh · P.N.Krishnan
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    ABSTRACT: An efficient in vitro propagation protocol was standardized in K. galanga, wherein shoot cultures were raised from rhizome with axillary bud explants in Murashige and Skoog (MS) medium supplemented with different hormonal regimes. Maximum 10.6±0.83 multiple shoots per explants were obtained in MS medium supplemented with 4.0 mgl-1 6-benzyl adenine (BA) along with 1.0 mgl-1 each of α-naphthaleneacetic acid (NAA) and kinetin. Subsequent 2-3 subculture passages enhanced the shoot multiplication rate to 3-4 times. The multiple shoots thus produced were having individual root system and elongated substantially when kept in the same medium for 4-6 weeks. There was no need of elongation and root induction phase and this two-step multiplication procedure reduced the period of plantlet production compared to the earlier protocols. The regenerated plants after a short hardening phase got established in the field at 80-90% efficiency and their genetic uniformity was confirmed through ISSR analysis. The protocol thus standardized is an efficient method for rapid propagation of this high value medicinal species by which at least 30 shoots per explants can be produced within 12 weeks duration. It offers the possibility of raising physiologically uniform plants for easy dissection of shoot tip meristems which can be efficiently utilized for subsequent long-term conservation through cryopreservation.
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    ABSTRACT: Axillary shoots were induced from shoot tip of Calamus thwaitesii suckers on Murashige and Skoog medium supplemented with 0.4 mg/L N6-benzylaminopurine and 0.1 mg/L each of thidiazuron and α-naphthaleneacetic acid (NAA). The shoots initiated were subcultured to fresh media of the same composition for shoot multiplication and multiplied shoots were transferred to half strength MS hormone-free media for shoot elongation. The elongated shoots (∼5cm) were then re-cultured to the media supplemented with 3.0 mg/L indole-3-butyric acid/4.0 mg/L NAA to raise plantlets which were subsequently analysed for genetic fidelity using inter simple sequence repeat markers. Out of 183 bands scored, 178 bands were monomorphic indicating 97.2% similarity. The observed low level of polymorphism between genotypes supports genetic consistency of these micro-clones that are likely to be genetically true to their parental origin. The clones thus obtained were hardened in the specially fabricated mist house at 29 ±2°C and 80±5% relative humidity for 3 months followed by shifting to green house for another 3 months of nursery establishment. The established plants when reintroduced to the selected forest segments of the Western Ghats, Kerala (India) showed 79.3% survival rate after 2 years of field transfer. The viable and highly reproducible in vitro cloning protocol demonstrated here for the first time can be used for the production of elite female clones for aforestation activities and sustained delivery of high quality raw materials to cane processing units for strengthening cane industry.
    Biologia 05/2014; 69(5). DOI:10.2478/s11756-014-0359-7 · 0.70 Impact Factor
  • 26th Kerala Science Congress, KVASU, Wayanad, Kerala; 01/2014
  • International Science Congress, Karunya University, Coimbatore, INDIA; 12/2013
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    ABSTRACT: An efficient protocol has been devised for the propagation and field establishment of Eulophia cullenii (Wight) Bl., a terrestrial orchid having ornamental potentialities, and is critically endangered in Western Ghats, India. Seeds extracted from 60–90-d-old capsules germinated in ½ MS, ¼ MS, Knudson C, or Mitra liquid medium developed into 1.4–2.5-mm-diameter protocorms in 60 d. Supplementation of organic additives like coconut water, peptone, yeast extract, and casein acid hydrolysate (CH) significantly enhanced protocorm growth. Upon subculture onto agar-gelled Mitra medium fortified with 0.05% CH, 56% of protocorms regenerated into shoots through the formation of linear mini-rhizomes. The regenerated shoots grew vigorously in ½ MS, producing new rhizomes. Mature rhizomes from axenic seedlings produced maximum (13 ± 1.4) shoots/whole rhizome in ½ MS fortified with 44.4 μM 6-benzylaminopurine (BAP), in 120–150 d. Horizontal and longitudinal halves of the rhizome also gave multiple shoots (6–8.5) in the presence of 44.4 μM BAP. Shoots or shoot clumps sub-cultured onto ½ MS basal medium produced roots followed by rhizomes in 60–150 d. Seedlings with mature rhizomes showed 70% establishment in the nursery and added a new rhizome at the end of one growth cycle. An average of 70.6% of the rhizomes originating from seedlings during the second growth cycle sprouted to produce new shoots, when planted in the native localities. Asymbiotic germination and cloning through rhizomes thus can provide a large number of vigorous plants of E. cullenii for ornamental exploitation as well as eco-restoration, if rhizome as storage organ is ensured in the propagule.
    In Vitro Cellular & Developmental Biology - Plant 11/2013; 49(5). DOI:10.1007/s11627-013-9521-0 · 1.16 Impact Factor
  • 16th All India Congress of Cytology and National Symposium on Gene, Environment and Health, Department of Botany, University of Kerala, Karyavattom, Thiruvananthapuram; 10/2013
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    A. S. Hemanthakumar · T. S. Preetha · P. N. Krishnan · S. Seeni
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    ABSTRACT: Zygotic embryos excised from immature green fruits of the rattan palm, Calamus thwaitesii and cultured for 16 weeks under optimum culture conditions in Murashige and Skoog (MS) medium supplemented with 31.67 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 35.23 μM 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) produced mixed (compact and friable) calli at 70 and 92 % rates. The semi-friable part of the callus (~500 mg) separated and subcultured in medium containing 2.22 μM 6-benzyladenine and 1.07 μM α-naphthalene acetic acid produced groups of 10.37 ± 0.60–21.52 ± 0.48 discrete globular embryoids of varied size in 6–8 weeks. Calli raised in presence of 2,4,5-T were relatively more prolific, friable and embryogenic than those induced by 2,4-D. Embryoids (2.0–3.0 mm) isolated and cultured in basal medium germinated into plantlets at 65 % efficiency while the immature (0.5–2.0 mm) ones produced calloid structures. Approximately 15 % of the in vitro plantlets raised from the 2,4-D-induced embryogenic calli produced secondary immature embryoids on the sheath and lamina parts of leaves which were isolated and cultured in basal medium developed into rooted plantlets at 62 % rate in 12–16 weeks. The continued growth of the embryo-derived callus through successive subcultures together with differentiation of embryoids into plantlets, and the formation of immature embryoids on in vitro plantlets in MS basal nutrient medium reports for the first time a reliable method of producing at least 116 plants from a single embryo in a year. Rooted plantlets treated with 50 % glycerin survived at 78 % rate after hardening and 82.7 % of the hardened plants reintroduced into forest segments showed uniform growth free of morphological abnormalities after 3 years of observation. In addition to embryogenesis, cryopreservation of the zygotic embryos through simple drying and encapsulation–dehydration methods resulting 60–70 % recovery rates also offers another option for long-term conservation and sustainable utilization of this plant genetic resource.
    06/2012; 3(3). DOI:10.1007/s13205-012-0083-3
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    ABSTRACT: Musa acuminata ssp. burmannica, one of the wild progenitors contributing 'A genome' to the present-day dessert bananas, has a long evolutionary history intervened by human activities. In this study, ISSR markers were used to analyze the pattern of genetic variation and differentiation in 32 individuals along with two reference samples (viz., Musa acuminata ssp. burmannicoides, var. Calcutta 4 and Musa balbisiana) of wild Musa, which corresponded to three populations across the biodiversity-rich hot spot of southern Western Ghats of India. High levels of genetic diversity were revealed both at the species and population levels, using Nei's diversity indices. The hierarchical analysis of molecular variance showed pronounced genetic differentiation, as 96% of the total variance was fixed within population and only 4% among populations. Nei's genetic differentiation coefficient (GST=0.1823) and low gene flow (Nm=1.18) further confirmed this. The positive correlation (Mantel test) between geographic distance and genetic distance (r=0.338 P<0.001) indicates geographic isolation as one of the key factors in shaping the population genetic structure. Grouping of individuals was largely in conformity with their spatial distribution, which was confirmed by UPGMA cluster analysis and PCA scatter plot clustering all 32 individuals into three major groups along a geographical gradient. The discontinuous distribution and dwindling population due to habitat fragmentation are serious threats to prevailing genetic diversity in this species. Conservation measures based on diversity pattern are suggested for long-term preservation and sustainable utilization of this precious genetic resource. KEY MESSAGE: A diverse germplasm of Musa acuminata ssp. burmannica exists in southern Western Ghats as a possible repository of useful resistant traits, which can be effectively utilized for crop improvement.
    Plant Cell Reports 05/2012; 31(9):1591-601. DOI:10.1007/s00299-012-1273-5 · 2.94 Impact Factor
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    R.K. Radha · William S. Decruse · P.N. Krishnan
    Current Frontiers in Cryopreservation, 03/2012; , ISBN: 978-953-51-0302-8
  • Recent trends and future Prospects of Biodiversity and Conservation, S.N.College, Punalur, Kerala; 03/2012
  • Kerala Science Congrees; 01/2012
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    ABSTRACT: In vitro propagation of diploid land race of Musa cv. ‘Ambalakadali’ was achieved through organogenesis both from shoot primordial meristems and male floral apices taken out from mature disease free field grown plants. Healthy cultures were successfully initiated from shoot primordial meristems when independent dosage of BAP at 4.0-mg/l was given in MS nutrient media. The inflorescence apices responded the most to the in vitro culture conditions at 6.0-mg l-1 BAP in MS media itself. In both the cases, culture proliferation requires comparatively lower dosages of BAP. Subsequent cultures displayed enhancement in rate of shoot initiation and multiplication in the inflorescence derived cultures. Transfer of shoots (4-5 cm) into MS basal medium containing 0.1% activated charcoal (AC) favoured generation of healthy shootlets and formation of profuse roots during a period of 4 weeks. The plantlets (15 cm) after acclimatization in green house were distributed to local farmers for field evaluation. Plants flowered normally within 12 months and produced uniform characters as that of the mother plants.
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    Radha R.K · Shereena S.R · Divya K · Krishnan P.N · Seeni S
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    ABSTRACT: An efficient micropropagation protocol was developed for direct shoot induction from the seedlings of Rubia cordifolia , a species sparsely distributed in the Western Ghats of India. Plant regeneration was achieved using shoot tip, nodal and split nodal half explants on Murashige and Skoog medium. Effect of plant growth regulators like 6-Benzyladenine, Kinetin, 6-Benzyladenine + Indole-3-acetic acid and 6-Benzyladenine + α-Naphthalene acetic acid on shoot multiplication and Indole-3-acetic acid, Indole-3-butyric acid and α-Naphthalene acetic acid on rooting was studied. R . cordifolia shoots showed abundant proliferation and rooting capacity, both of which are significantly influenced by the varying concentrations of the different plant growth regulators. The optimum number of shoot obtained were 5.9 and 5.2 per explants in 2 weeks on the medium supplemented with 1 mg L<SUP>-1</SUP> Benzyladenine and 0.02 mg L<SUP>-1</SUP> Indole-3-acetic acid in nodes and split vertical halves of the node respectively. The results suggest that the nodal explants (intact and split vertical halves) are better sources of shoot formation than the shoot tip explant. Shoot multiplication was rapid and consistent for 4 subcultures with 0.5 mg L<SUP>-1</SUP> Benzyladenine. The best root induction (98%) and survival was achieved on 1 mg L<SUP>-1</SUP> Indole-3-butyric acid followed by 1 mg L<SUP>-1</SUP> Indole-3-acetic acid. Rooted plantlets were successfully transferred to green house conditions with 89% survival. Micropropagated plants displayed normal phenotypes in ex situ conditions. These plantlets can be used to replenish declining populations in the wild, for the extraction of bioactive compounds and reducing pressure on wild stocks.
    International Journal of Botany 01/2011; DOI:10.3923/ijb.2011.90.96
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    ABSTRACT: Poeciloneuron pauciflorum is a narrow endemic having highly restricted distribution in the southern-western Ghats region of India. 18 accessions of P. pauciflorum collected from four different locations were analyzed for genetic varia- tion using 20 random primers. Out of 141 amplicons generated, 130 of them were polymorphic (92.20% polymorphism). Contrary to the general concept of low genetic variation associated with endemic plant species, P. pauciflorum exhibits high genetic diversity as the similarity index value based on Nei & Li’s similarity coefficient ranges from 0.36 to 0.95 with mean GS = 0.72 and Shannon’s information measure (0.43). Cluster analysis showed grouping of all accessions from the State of Tamil Nadu into two major clusters with few outliers while those from the State of Kerala also clus- tered with them. Accessions from Kalliankadu forest segment harbors maximum diversity as indicated by various ge- netic diversity indices like h, I, Ht, Hs, Gst, PL and hence this site is recommended for in situ conservation of this nar- row endemic. The main factors responsible for the high level of genetic diversity among accessions are probably re- lated to the reproductive isolation and ecological breadth. The strong genetic variability among accessions indicates that the management for the conservation of the genetic diversity in P. pauciflorum should aim to preserve every acces- sion. The present study assumes significance as it negotiates endemism and genetic variation in tree species, a global phenomenon having wide implications in species diversity and conservation.
    American Journal of Plant Sciences 01/2011; 2(03):416-424. DOI:10.4236/ajps.2011.23047
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    G.Praveen · S.Mukunthakumar · P.N. Krishnan · S. Seeni
    National Conference on Banana; 10/2007
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    S.Mukunthakumar · G.Praveen · P.N. Krishnan · S.Seeni
    National conference on Banana; 10/2007
  • C. G. Sudha · P. N. Krishnan · P. Pushpangadan · S. Seeni
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    ABSTRACT: This study reports a protocol for successful micropropagation of Decalepis arayalpathra (Joseph and Chandras) Venter. (Janakia arayalpathra Joseph and Chandrasekhran; Periplocaceae), a critically endangered and endemic ethnomedicinal plant in the southern forests of the Western Ghats which is overexploited for its tuberous medicinal roots by the local Kani tribes. Natural regeneration is rare and conventional propagation is difficult. Conservation of the species through micropropagation was attempted. The nodal explants of greenhouse-raised plants, were more desirable than cotyledonary nodal explants of aseptic seedlings. The basal nodes (73%) of 12–16-wk-old greenhouse-grown plants cultured in Murashige and Skoog (MS) medium containing 12.96 μM 6-benzyladenine (BA), 2.48 μM 2-isopentenyladenine (2-ip) and 2.68 μM α-naphthaleneacetic acid (NAA) formed 16–17 cm long unbranched robust solitary shoots in 8 wk. Cotyledonary nodal explants cultured in the same medium showed multiple shoot formation and axillary branching. But the shoots were thin, fragile and not suitable for mass propagation. Single nodes of a solitary shoot subcultured on MS medium containing 2.22 μM BA and 0.24 μM 2-ip together produced 9.8±0.3 nodes from 18.0±0.6 cm long shoots within 5–6 wk. The basal nodes of the shoots so formed were repeatedly subcultured to increase the stock of propagules while the 2.5–3.0 cm terminal cuttings were used for rooting. The best root induction (68%) and survival (86%) was achieved on half-strength MS medium supplemented with 1.07 μM NAA. Field-established plants showed uniform growth and phenotypic similarity to parental stock.
    In Vitro Cellular & Developmental Biology - Plant 01/2005; 41(5):648-654. DOI:10.1079/IVP2005652 · 1.16 Impact Factor
  • C. G. Sudha · P. N. Krishnan · P. Pushpangadan
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    ABSTRACT: A rapid micropropagation system was established forHolostemma annulare (Roxb.) K. Schum., (H. ada-kodien R. Br. ex Schult; Asclepiadaceae), a rare medicinal plant. Shoot tips (0.5–0.8 cm) and terminal and basal nodes (1.0–1.5 cm) harvested from actively growing shoots of conventionally raised plants were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of 6-benzyladenine (BA) and α-naphthaleneacetic acid (NAA). Multiple shoot formation (3.8) was observed in 68% of basal nodes cultured on medium with optimum concentration of 4.43 μM BA and 0.54 μM NAA after 8 wk. Terminal nodes were not suitable for inducing multiple shoots. Irrespective of the orientation (vertical/horizontal), all shoot tip explants responded with a single shoot in all the combinations of plant growth regulators tried. Effects of other cytokinins (kinetin and 2-isopentenyladenine) and auxins [indole-3-acetic acid and indole-3-butyric acid (IBA)] to enhance the regeneration potential of basal nodes were analyzed. Shoots were multiplied by subculture of basal nodes and stumps (the original explant tissue free of shoots, but with remnant axillary, meristem and two or three protruding buds) in a reduced concentration of BA (2.21 μM) and NAA (0.27 μM). Liquid medium for multiplication was found to be ineffective due to a high degree of hyperhydricity. To make the multiplication process cost effective, culture bottles with polypropylene, caps were used for multiplication. The best root induction (75%) and survival (80%) was achieved on 0.5 strength MS medium supplemented with 1.48 μM IBA. Field-established plants had uniform growth habit traits in terms of height of plants and number, length, and weight of the tuberous roots.
    In Vitro Cellular & Developmental Biology - Plant 12/1997; 34(1):57-63. DOI:10.1007/BF02823124 · 1.16 Impact Factor