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Red sandalwood (Pterocarpus santalinus L. f.): biology, importance, propagation and micropropagation

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Abstract

Pterocarpus santalinus L. f. (Fabaceae; red sanders) is prized for its wood whose colour and fragrance is due to the presence of santalins that have pharmaceutical and industrial uses. Red sanders is listed as an endangered plant species on the IUCN red data list as a result of the exploitation of its wood and essential oil. This review emphasizes the pollination biology, seed germination, vegetative propagation and micropropagation of P. santalinus. Excessive use of P. santalinus has also caused the emergence of various adulterants, so accurate identification is essential.
REVIEW ARTICLE
Red sandalwood (Pterocarpus santalinus L. f.): biology,
importance, propagation and micropropagation
Jaime A. Teixeira da Silva
1
Mafatlal M. Kher
2
Deepak Soner
3
M. Nataraj
2
Received: 3 November 2017 / Accepted: 6 February 2018 / Published online: 20 June 2018
The Author(s) 2018
Abstract Pterocarpus santalinus L. f. (Fabaceae; red
sanders) is prized for its wood whose colour and fragrance
is due to the presence of santalins that have pharmaceutical
and industrial uses. Red sanders is listed as an endangered
plant species on the IUCN red data list as a result of the
exploitation of its wood and essential oil. This review
emphasizes the pollination biology, seed germination,
vegetative propagation and micropropagation of P. san-
talinus. Excessive use of P. santalinus has also caused the
emergence of various adulterants, so accurate identification
is essential.
Keywords Conservation Fabaceae IUCN red data list
Medicinal plant Micropropagation Red sanders
Historical, cultural, medicinal, and economic
importance of red sanders as a basis
for conservation
Pterocarpus santalinus L. f. (Fabaceae) is most commonly
known as red sandalwood in English, but it also has other
common names in several languages (Table S1). Ptero-
carpus is derived from the Greek words pteron (wing) and
karpos (fruit), referring to the winged pod, while santalinus
originates from the Latin sandal and inus (meaning similar
to), i.e., a plant with characteristics similar to Indian san-
dalwood, Santalum album L. (Botanical Survey of India
2012). Like African or Nepalese sandalwood (Teixeira da
Silva et al. 2016a) and Indian sandalwood (Teixeira da Silva
et al. 2016b), P. santalinus is also prized for its hard, dark-
purple, bitter heartwood (Navada and Vittal 2014). In India,
the natural range of P. santalinus used to be a very restricted
area of 15,540 km
2
in the southeast (Sarma 1993). Cur-
rently, P. santalinus is found exclusively in a well-defined
forest tract of Andhra Pradesh in Southern India (Raju and
Nagaraju 1999; Prakash et al. 2006; Balaraju et al. 2011),
but is also found in the Chinese provinces of Yunnan,
Guangdong and Guangxi, and on Hainan Island, where it is
referred to as zitan (Kaner et al. 2013).
The colour and fragrance of P. santalinus heartwood are
derived from santalins while the pleasent aroma is caused by
the presence of terpenoids (Kumar et al. 1974). A dye pre-
pared from the heartwood of P. santalinus is used as a stain in
light microscopy (Banerjee and Mukherjee 1981;SenGupta
and Mukherjee 1981), as a coloring agent in pharmaceutical
preparations, in food, leather and textile industries (Ankalaiah
The online version is available at http://www.springerlink.com
Corresponding editor: Yu Lei.
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s11676-018-0714-6) contains supple-
mentary material, which is available to authorized users.
&Jaime A. Teixeira da Silva
jaimetex@yahoo.com
&Mafatlal M. Kher
mafatlalmkher@gmail.com
&Deepak Soner
deepaksoner@gmail.com
&M. Nataraj
mnatarajspu@gmail.com
1
P. O. Box 7, Miki-cho post office, Ikenobe 3011-2,
Kagawa-ken 761-0799, Japan
2
P.G. Department of Biosciences, Sardar Patel University,
Sardar Patel Maidan, Vadtal Rd., P.O. Box 39,
Vallabh Vidyanagar, Gujarat 388120, India
3
Resonance, Plot No - 21/5, Near Regional Science Centre,
Acharya Vihar, Bhubaneswar, Odisha 751013, India
123
J. For. Res. (2019) 30(3):745–754
https://doi.org/10.1007/s11676-018-0714-6
et al. 2017), and as a textile dye (Gulrajani et al. 2002). The
medicinal properties of P. santalinus have been extensively
reviewed elsewhere (Navada and Vittal 2014; Azamthulla
et al. 2015) and will not be covered in this review. However,
multiple uses (Table S2), ethnomedicinal uses (Table S3), and
phytochemistry (Table S4) have been provided as supple-
mentary tables to offer a more rounded appreciation of this
tree in the context of this review.
The texture and colour differentiate good quality from
poor quality trees, with ‘‘wavy grain wood texture with
intense red color’’ in the former and ‘‘straight grain wood
texture with light red color’’ in the latter (Prakash et al.
2006), and it is the superior quality of P. santalinus that
makes it popular in the furniture industry (Prakash et al.
2006; Arunkumar et al. 2011; Arunkumar and Joshi 2014;
Azamthulla et al. 2015). In Japan, P. santalinus is used to
make carvings and musical instruments, shamisen and koto
(Kukrety et al. 2013b; Arunkumar and Joshi 2014; Azam-
thulla et al. 2015; Ramabrahmam and Sujatha 2016), as well
as name seals or hankos. In Buddhism, P. santalinus is
considered to be a symbol of holiness, and is thus used for
carved statues, as a constituent of incense (Wu et al. 2011),
and for cremation (Ramakrishna 1962). In China, P. san-
talinus wood has a long history of use in furniture and other
valuable wood products (Berliner 1996; Kaner et al. 2013).
The export of P. santalinus from India to Europe started
in the 17th century, mainly for fabric dyeing (Vedavathy
2004). The Herbal Folklore Research Centre in Tirupati,
India, estimated that from 500 planted trees ha
-1
, at least
500 kg of heartwood per tree can be obtained after
25 years, thus 25 t ha
-1
of wood plantation (Vedavathy
2004). At 2004 prices of Rs. 75 kg
-1
, such a plantation
would yield a return of Rs. 177.5 lakhs ha
-1
(US$375,000 ha
-1
) (Vedavathy 2004). Current market
prices are, however, unknown to the authors, although
prices are likely to be high since natural P. santalinus
stands have been in decline as a result of this overex-
ploitation for commercial purposes, earning it an endan-
gered status since 1997 (IUCN 2018).
This review provides an overview of the reproductive
biology, seed germination and micropropagation of P.
santalinus as tools for its conservation and large-scale
propagation.
Basic flowering biology, and sexual and vegetative
reproduction
Pollination and seedset
The P. santalinus tree flowers in the dry season (Rao et al.
2001; Rao and Raju 2002). The flowers are papilionaceous,
bisexual, large and and yellow (Rao and Raju 2002).
Flowering is discontinuous, blooming at intervals of 2–5 d
(Rao et al. 2001). Flowers open at night and the primary
pollinators are Apis dorsata,A. cerana indica and A. florea
(Rao and Raju 2002). P. santalinus, which shows facultative
xenogamy, tends to eliminate growing fruits from self-polli-
nated flowers, i.e., there is large-scale abortion of flower buds,
flowers and fruit (Rao et al. 2001), and has very low fruit set
(-6%), 52% of which set seed (Rao and Raju 2002).
Seed germination
Traditional seed propagation of P. santalinus yields low
germination percentages due to a hard testa, poor viability,
and sensitivity to temperature (Kumar and Gopal 1975;
Dayanand and Lohidas 1988; Anuradha and Pullaiah 1998;
Naidu 2001a,b; Naidu and Rajendrudu 2001). Dried,
soaked and scarified P. santalinus pods resulted in 49%
germination (Kumarasinghe et al. 2003) although seed
germination in natural stands or under artificial propagation
is generally low (-30%) (Kumar and Gopal 1975; Day-
anand and Lohidas 1988; Kalimuthu and Lakshmanan
1995; Naidu 2001a,b;Naidu and Rajendrudu 2001).
Alternate wetting and drying every 48 h enhanced germi-
nation, reaching 73% (Vijayalakshmi and Renganayaki
2017). Seed germination, seedling height, and root collar
diameter were all significantly stimulated by fire (Kukrety
et al. 2013b). Presoaking P. santalinus pods with 500 mg/L
gibberellic acid for 24 h resulted in 66.7% seed germina-
tion, as well as improved plant growth and seedling sur-
vival relative to other treatments with tap water, luke warm
water, gibberellic acid, H
2
SO
4
or HCl (Patel et al. 2018).
Vegetative propagation
Vegetative propagation of P. santalinus by semi-hardwood
cuttings, cleft grafting, or air layering is not able to produce
stock numbers required for effective preservation or for
commercial purposes (Kedharnath et al. 1976;Kesava
Reddy and Srivasuki 1990). Relative to seed germination,
there are almost no studies on ex vitro vegetative propaga-
tion for red sanders. However, to provide elite germplasm
with desired traits, such as the wavy grain or phytochemicals
such as santalins, vegetative propagation under controlled
conditions is desirable, and in vitro propagation allows for
the production of true-to-type plants via micropropagation
such as axillary shoot multiplication or shoot tip culture at a
large scale, to continuously produce plantlets with uniform
characteristics. In tree biotechnology, such as for Indian
sandalwood (Teixeira da Silva et al. 2016b), in vitro prop-
agation also allows for the improvement of desired charac-
teristics such as pathogen resistance or improved wood
quality by genetic engineering. The next section assesses the
progress of micropropagation of P. santalinus.
746 J. A. Teixeira da Silva et al.
123
Micropropagation
Explants
The explant source (i.e., mother plant) and the procedure to
surface disinfect explants are important aspects underlying
the success of a tissue culture protocol (Leifert et al. 1994;
Teixeira da Silva et al. 2016c). Information about the
explants used for the in vitro propagation of P. santalinus,
as well as surface disinfection protocols, are summarised in
Table 1.P. santalinus seedlings derived from in vitro seed
germination have been a popular source of explants, while
in vitro germinated seedlings, shoot tips, cotyledons,
hypocotyls, mesocotyl and nodes have also served as
popular sources of explants for culture initiation since they
do not require surface disinfection (Lakshmi Sita et al.
1992; Anuradha and Pullaiah 1999a,b; Chaturani et al.
2005; Rajeswari and Paliwal 2008; Balaraju et al. 2011;
Vipranarayana et al. 2012; Warakagoda and Subasinghe
2013). In terms of ex vitro sources of explants, Prakash
et al. (2006) used young terminal shoot cuttings collected
from mature trees in winter as the explant; Ashrafee et al.
(2014) used leaf segments from 1 to 2 year old plants while
Sarita et al. (1988) used nodes and terminal cuttings.
Basal medium
The most commonly used and preferred basal medium for
in vitro studies on P. santalinus is Murashige and Skoog
(1962) (MS) medium (Table 2). Lakshmi Sita et al. (1992)
used Gamborg’s B
5
medium (Gamborg et al. 1968) with
2% sucrose and 0.8% agar to multiply axillary shoots from
shoot tips derived from seedlings germinated in vitro.
Chaturani et al. (2006) used Anderson medium (Anderson
1980) and Vitis medium (Chee and Pool 1987) to germinate
seed. Anuradha and Pullaiah (1999a) employed half-
strength B
5
medium supplemented with 0.05% activated
charcoal to germinate seeds in vitro then used B
5
medium
with 8.88 lM 6-benzyladenine (BA) for shoot tip culture.
In vitro propagation from predetermined meristems
Three predetermined meristems were employed in P.
santalinus tissue culture: shoot tips, cotyledonary nodes
and nodes from mature trees (Table 2). Shoot tips from
in vitro germinated seedlings were used by Lakshmi Sita
et al. (1992), Anuradha and Pullaiah (1999a), and Balaraju
et al. (2011) for shoot tip culture, with either BA as the
most effective cytokinin (Lakshmi Sita et al. 1992; Anu-
radha and Pullaiah 1999a) or a combination of BA and
thidiazuron (Balaraju et al. 2011). Cotyldenory nodes were
sucessfully applied for the in vitro propagation of P.
santalinus (Anuradha and Pullaiah 1999a; Arockiasamy
et al. 2000; Rajeswari and Paliwal 2008; Warakagoda and
Subasinghe 2013). BA, alone or combined with other
cytokinins or auxins, has frequently been utilized for the
micropropagation of P. santalinus (Table 2). Prakash et al.
(2006) cultured nodes of mature trees directly on filter
paper bridges employing liquid MS medium containing
1.16–9.30 lM kinetin or 1.11–8.88 lM BA, as well as an
antioxidant, observing that 4.44 lM BA was optimum for
bud break and shoot multiplication.
In vitro propagation (callogenesis, regeneration
and somatic embryogenesis)
Leaf, cotyledon, root, internode and nodal segments (pre-
sumably with axillary buds) from in vitro P. santalinus
seedlings formed callus, but shoot regeneration was not
reported (Chaturani et al. 2005). Callus was induced from
leaves and internodes of P. santalinus by Ashrafee et al.
(2014) solely to assess antibiotic activity against Aero-
monas and Pseudomonas but regeneration was not asses-
sed. Details of effective plant growth regulator
concentrations and combinations, medium composition,
and explant type, as well as their effects on morphogenesis
are presented in Table 2.
Rooting and acclimatization
Sucessful roooting of in vitro-raised plants followed by
effective acclimatization and successful transfer of in vitro-
propagated plants to field conditions is the final objective
of any micropopagation protocol and care is needed to
avoid hyperhydricity in in vitro-raised plants, which tend to
display poor rooting efficiency (Ruffoni and Savona 2013;
Teixeira da Silva et al. 2017b). Rooting and acclimatization
protocols for in vitro-raised shoots of P. santalinus are
summarized in Table 2. Only a few studies have quantified
the survival of micropropagated plants (Lakshmi Sita et al.
1992; Prakash et al. 2006; Rajeswari and Paliwal 2008;
Balaraju et al. 2011; Warakagoda and Subasinghe 2013).
Among the 12 reports on P. santalinus tissue culture,
in vitro rooting employed full-strength, half-strength and
quarter-strength MS medium (Table 2). According to
Arockiasamy et al. (2000), quarter-strength MS medium
supplemented with 5.71 lM IAA was effective for 76.2%
rooting of shoots derived from cotyledenory nodes, but
acclimatization and survival of plantlets were not reported.
Vipranarayana et al. (2012) applied a pulse treatment of
7.34 lM IBA in half-strength MS but details about survival
were not reported. Rajeswari and Paliwal (2008) achieved
85% plantlet survival ex vitro after a pulse treatment of
5lM IAA and 1 lM IBA for 25 d. In contrast, Warak-
agoda and Subasinghe (2013) showed limited success (46%
Red sandalwood (Pterocarpus santalinus L. f.): biology, importance, propagation and747
123
Table 1 Explant source, size and surface sterilization procedures for preparation of tissue culture studies of Pterocarpus santalinus (chrono-
logical listing)
Explant source Explant type, size and density; culture
vessel
Surface sterilization and preparation References
Seeds (soaked and dried for 15 d) ?
seedlings. Age and source of mother
plant NR
Size of shoot tips (15-d-old seedling)
NR. 5–8 mm shoot tips and nodes
from in vitro grown shoots. Test tubes
(15 mL/tube)
Shoot tips: RTW (duration NR) ?soap
(soap name, duration of treatment and
concentration NR) ?0.1% HgCl2
15 min ?3-4X SDW
Lakshmi Sita
et al. (1992)
Seeds from the wild ?seedlings. Age
of mother plant NR
Roots, hypocotyls, mesocotyls,
cotyledons, shoot tips, nodes, leaves,
internodes (size NR for all explants)
from 15-d old seedlings 6–7 cm tall
with 3–4 nodes. Test tubes (1
explant/tube)
Pods: 50% HCl ?50% EtOH 2–3 h ?
TRW ?dried for 2 d ?pods opened
and seeds sown directly in vitro
Anuradha and
Pullaiah
(1999a)
Seeds from the wild ?seedlings. Age
of mother plant NR
Hypocotyls (1 cm), epicotyls (1 cm),
cotyledons (1.5 cm), shoot tips
(0.5 cm), internodes (0.5 cm), axillary
nodes (0.5 cm) from 20-d old
seedlings. Test tubes (1 explant/tube)
Seeds from dried pods: 70% alcohol
1 min ?0.1% HgCl2 ?0.1% sodium
dodecyl sulfate 10 min ?5X DDW
?SDW 24 h ?SDW replaced every
8h
Arockiasamy
et al. (2000)
Pods (\3to[5 cm) including wing.
Age of mother plant NR
Seeds from pods of various sizes. Pods
stored at 28 ±5C for 1–4 weeks.
Culture vessel NR
Seeds: 5% Teepol (duration NR) ?
RTW 2 h ?0.1% HgCl2 ?2 drops
Tween-20 (5–25 min) ?3X SDW
10 min
Chaturani et al.
(2006)
10-y-old tree, sampled in Nov.-Jan. Mature nodes from terminal shoots
(7–8 cm long). 25 9150 mL test
tubes (1 explant/tube)
Shoots: 1% Teepol 30 min ?cut into
nodal segments 2–3 cm long ?70%
EtOH 2 min ?0.1% HgCl2 ?0.1%
Tween-20 7 min ?5X SDW
Prakash et al.
(2006)
Mature pods and nodes (forest and
campus culture)
Pods scarified in boiling water (5 min)
or 5% H2SO4 (10 min). Culture vessel
NR
Seeds and nodes: RTW 30 min ?testa
removed ?2% Bavistin (15 min for
nodes, 30 min for seeds) ?70%
EtOH 2 min ?0.1% HgCl2 (15 min
for nodes, 12 min for seeds) ?4-5X
SDW
Padmalatha
and Prasad
(2007,2008)
Seeds ?seedlings. Age and source of
mother plant NR
Seedling-derived cotyledonary nodes
(1.5 cm long), nodal segments (1 cm
long). Test tubes (1 explant/tube)
Explants from 30-d-old seedlings: RTW
1h?0.025% Tween-20 10 min ?
3X DW ?0.1% HgCl2 10 min ?3X
SDW
Rajeswari and
Paliwal
(2008)
Seeds from the wild ?seedlings Shoot tips of 20-d-old in vivo seedlings.
50-mL Borosil test tubes (1–2
explants/tube)
Peeled seeds: 1% Bavistin (fungicide)
10 min ?wash with H2O ?
50–300 ppm GA3 24 h. Apical
meristem explants: RTW 10 min ?
DW ?some drops Tween-20 5 min
?SDW 2-3X ?1% Bavistin 5 min
?SDW ?70% EtOH 30 s ?SDW
2-3X ?0.1% HgCl2 3 min ?4X
SDW
Balaraju et al.
(2011)
In vitro seedlings (age NR) Nodal segments; one explant per test
tube (150 mm 925 mm)
Seeds: RTW 30–40 min ?5% Teepol-
B-300 (wetting agent) stirring 15 min
?1% Bavistin Carbandazim
(fungicide) 10 min ?DW 30 min ?
70% EtOH 30 s ?0.05% HgCl2
5–10 min ?4X SDW
Vipranarayana
et al. (2012)
748 J. A. Teixeira da Silva et al.
123
of plantlets rooted) ex vitro with 49,000 lM IBA, possibly
because of the excessively high concentration of this auxin.
Variability in quality and quality control
There is a problem with the adulteration and falsification of
plant material in the P. santalinus market. The heartwood
of Adenanthera pavonina Willd. (Mimosaceae), known as
‘Ranjana’ and ‘Raktakambal’ in West Bengal and ‘Bari
Gumchi’ in the northern parts of India, is often sold as a
fake substitute for P. santalinus, while artificially colored
wood shavings and the sawdust of some other trees are also
sold on the market as cheap substitutes (Botanical Survey
of India 2012). In China, the manufacture of furniture
utilizes Dalbergia louvelii R. Vig. (violet rosewood) as a
substitute for P. santalinus since both plants have a very
similar appearance and anatomical characteristics, and
cheaper D. louvelii is often illegally used to impersonate
the valuable P. santalinus (Zhang et al. 2014). Zhang et al.
(2014) used conventional infrared spectroscopy (FT-IR),
second derivative infrared (SD-IR) spectroscopy and two-
dimensional correlation infrared (2DCOS-IR) spectroscopy
to differentiate furniture made of P. santalinus wood from
furniture made from D. louvelii. They observed that P.
santalinus wood had a higher holocellulose content than D.
louvelii wood while D. louvelii had more NaOH- and
benzyl-alcohol-based extracts than P. santalinus.
The size and age of trees affects the heartwood content
and wood density of P. santalinus (Suresh et al. 2017).
Woody anatomy such as grain waviness can be used to
delimit and identify P. santalinus (Rawat and Uniyal 1996;
Gasson and MacLachlan 2010). The Botanical Survey of
India (2012) used various anatomical methods such as
maceration, scanning electron microscopy, exo- and
endomorphic features, and fluorescence analysis to cor-
rectly identify P. santalinus wood samples.
Molecular markers are regularly utilized to measure the
degree of genetic variation within natural or breeding
populations, and have been extensively used in Indian
sandalwood research (Teixeira da Silva et al. 2017a). In P.
santalinus, RAPD (random amplified polymorphic DNA)-
based marker analysis was used to detect variations in
micropropagated plants raised from shoot tips, verifying
that in fact no variation existed (Balaraju et al. 2011).
RAPD was also used by Usha et al. (2013) to detect vari-
ation among nursery-grown plants. Variation in genetic
distance among natural accessions, detected by RAPD
markers, reflected a high level of DNA polymorphism due
to outcrossing (Padmalatha and Prasad 2007; Usha et al.
2013). Jhansi Rani and Usha (2013) developed a sequence
characterized amplified region (SCAR) marker to differ-
entiate wavy from straight-grained plants at the seedling
stage. Jyothi et al. (2014) reported differences in the
quantity of genomic DNA in samples collected from dif-
ferent locations in Andhra Pradesh, India.
Therefore, quality control, as assessed by anatomical or
chemical methods, is essential to verify the originality of P.
santalinus wood while molecular methods serve to confirm
genetic stability.
Table 1 continued
Explant source Explant type, size and density; culture
vessel
Surface sterilization and preparation References
1. Seeds from green-brown pods from
25-y-old trees
2. Age of mother plants in greenhouse
NR. Greenhouse conditions NR.
Terminal bud removed and sprayed
with 10 mg/l BA at 2-w intervals. 70%
thiophanate methyl (topsin) sprayed at
100 mg/l 24 h before collecting
explants. Plants treated with 200 mg/l
Albert’s solution (liquid fertilizer) at
2-w intervals
1. Mesocotyl segments, cotyledonary
nodal segments, shoot tips, from 20-d-
old in vitro germinated seedlings and
seedlings
2. Immature and semi-hard shoot
segments
Culture vessel and other conditions for 1
and 2 NR
Seeds: 10% Clorox
(fungicide) 20 min
?70% EtOH 2 min ?rinse NR
Shoot segments: 5% Teepol 5 min ?
RTW 30 min ?0.3% topsin solution
1h?2X SDW ?Clorox
?2 drops
Tween-20 (10, 15, 20% for 10, 15,
20 min each) ?70% EtOH 2 min ?
2X DW. Whole process repeated twice
Warakagoda
and
Subasinghe
(2013)
1–3-y-old trees Leaves and internodes. Size and density
NR; test tubes
Leaves: wash in DW ?70% EtOH 30 s
?0.1% HgCl2 3 min. Internodes:
70% EtOH 2 min ?0.1% HgCl2 ?
2–3 drops Tween-20 7 min. No rinses
described for both explants
Ashrafee et al.
(2014)
dday(s), DW distilled water, DDW double distilled water, EtOH ethyl alcohol (ethanol), GA
3
gibberellic acid, HgCl
2
mercury chloride, IZE
immature zygotic embryo, NaOCl sodium hypochlorite, NR not reported in the study, RTW running tap water, ssecond(s), SDW sterilized (by
autoclaving) distilled water, SW sterilized water, yyear(s)
Red sandalwood (Pterocarpus santalinus L. f.): biology, importance, propagation and749
123
Table 2 In vitro conditions for tissue culture studies of Pterocarpus santalinus (chronological listing)
Culture medium, PGRs,
additives, subcultures
Culture conditions
a
Experimental outcome, maximum productivity, acclimatization
and variation
References
B
5
?0.88 lM or 4.44 lM
BA ?0.46 or 4.6 lM Kin
(SIM). MS ?
5.71–28.59 lM IAA or
4.9–24.42 lM IBA
(RIM). pH 5.6–5.8. 2%
sucrose. 0.8% agar.
Subculture every 4–5 w
16-h PP. CWFT.
1200 lx. 25 C.
RH NR
Shoot tips from in vitro seedlings produced 4–5 cm shoots with
4–5 nodes. Shoot tips from in vitro grown shoots produced up to
8 shoots 3–5 cm long on B
5
?4.44 lMBA?4.65 lM Kin
within 4–6 w. Nodal explants produced 1 shoot/explant. 80%
rooting on IAA vs. 30–40% on IBA in RIM. 5.71–11.43 lM
IAA produced adventitious roots but 28.59 lM IAA produced a
thick tap root. Acclimatization in sterilized soil ?sand (1:1)
with 50% survival. 60% survival when kept in liquid RIM for 2
w then transferred to test tubes with only water for 1 w and the
finally to plastic covered pots
Lakshmi Sita et al. (1992)
B
5
?0.05% AC ?
0.44 lM BA (SG). B
5
?
8.88 lM BA (SIM). MS
?0.57 lM IAA ?
0.49 lM IBA ?0.53 lM
NAA (RIM). pH 5.7–5.8.
3% sucrose. Gelling agent
NR
NR 40–70% germination in 24 h. Only shoot tips, nodes and
mesocotyls formed shoot buds and multiple shoots; the five other
explants induced callus. Mesocotyls formed maximum
shoots/explant (7–8). MS and WPM not as effective as B
5
as
SIM basal medium. Acclimatization claimed in sand ?soil, but
not quantified
Anuradha and Pullaiah (1999a)
MS ?2% sucrose ?0.6%
agar (SG). MS ?
0.53 lM NAA ?
4.44 lMBA?4.65 lM
Kin (SIM). MS ?
5.71 lM IAA (RIM).
Carbon source, gelling
agent, pH NR
16-h PP. Light
source NR.
1200 lx. 26 C.
RH NR
10.4 shoots/cotyledon on SIM. No shoots formed from epicotyls,
hypocotyls or internodes. 76.2% of cultures rooted.
Acclimatization claimed in sterilized garden soil ?sand (1:1)
and watered with RIM for 1 w, but not quantified
Arockiasamy et al. (2000)
MS, WPM, Anderson or
Vitis basal medium ?AC
conc. NR or without AC
(SG). pH NR. 3% sucrose.
08% agar
12-h PP. Light
source NR. 23 ±
2C. RH NR
90% germination after 15 min exposure to 0.1% HgCl
2.
\3cm
pods were either seedless or with fragile seeds. About 95% of
seeds from pods [5 cm in size germinated. No correlation
between size and germination period. 96% germination in pods
stored for 1 w at 28 ±5C. Storage period and browning were
inversely proportional to germination efficiency. Rapid (within 6
d) germination (92%) with 10 mm hypocotyls was possible from
seeds cultured on Anderson medium without AC.
Chaturani et al. (2006)
Liquid MS ?4.4 lMBA?
2.2 lM TDZ (SIM,
SMM) with 6-w
subcultures on paper
bridges. MS ?4.9 lM
IBA (RIM). pH 5.8. 3%
sucrose. 0.8% agar (RIM
only)
16-h PP. CWFT. 50
lEm
-2
s
-1
.25±
2C. 65% RH
Subculture on paper bridges improved nodal explant survival more
than all antioxidants tested but 80% of cultures showed
browning. 74–75% of nodes formed axillary shoots. An 8.3-fold
increase in shoots by the 6th subculture. 70% survival after
acclimatization in autoclaved soil ?FYM (4:1) after 5 months
Prakash et al. (2006)
750 J. A. Teixeira da Silva et al.
123
Table 2 continued
Culture medium, PGRs,
additives, subcultures
Culture conditions
a
Experimental outcome, maximum productivity, acclimatization
and variation
References
MS ?13.32 lM BA (SIM,
nodes). MS ?4.44 lM
BA ?9.30 lM Kin (SIM,
seeds). MS ?4.44 lM
BA (SMM, nodes, seeds).
Auxin-free MS ?0.25%
phytagel (RIM). pH NR.
3% sucrose. 0.6% agar
16-h PP. CWFT.
83.6 lEm
-2
s
-1
.25
±2C. 60–70% RH
17 shoots/seed explant on SIM, then SMM, with 90% explant
response. Rooting data NR. Low (20%) survival of acclimatized
plantlets in Soilrite
?manure ?sand (1:1:1)
Padmalatha and Prasad (2008)
MS ?2.5 lMBA?2lM
2iP (SIM, SMM). Dip in
5lM IAA ?1lM IBA
(ex vitro RIM). pH NR.
3% sucrose. 0.8%
Bactoagar
16-h PP. CWFT.
60 lmol m
-2
s
-1
.
24 ±2C. RH NR
Max. of 4/4 shoots/cotyledonary node in 2nd subculture in 95% of
cotyledonary nodes. 82.5% of shoots induced roots. 95%
survival of acclimatized plantlets in coarse sand ?clay ?FYM
(1:1:1). Tissue-cultured plants showed better morphological
performance than seedlings
Rajeswari and Paliwal (2008)
MS ?1 mg/l BA ?
0.45 lM TDZ (SIM).
Subculture every 4 w. MS
?2.22 lMBA?
0.28 lMGA
3
(shoot
elongation). MS ?
0.49 lM IBA (RIM)
using 3–4 cm long shoots
with 4–5 leaves. After 4
w, transfer to PGR-free
MS (root elongation). pH
5.8. 2% sucrose. 0.8%
agar
16-h PP. CWFT.
35–50 lmol m
-2
s
-1
.22±1C. RH
NR
% SG NR. 83% of shoot tips formed new shoots, with 11
buds/explant after 45 d. 60% of shoots rooted. 73.3% survival of
acclimatized plantlets in organic manure and garden soil ?sand
(1:1) under in vitro culture conditions. RAPD used to confirm
lack of variation
Balaraju et al. (2011)
MS ?2lMGA
3
(SG). MS
?1 mg/l BA ?0.5 mg/l
NAA (SIM). Pulse in
1.5 g/l IBA ?MS
(RIM). pH 5.8. 3%
sucrose. 0.8% agar
16-h PP. CWFT.
50 lmol m
-2
s
-1
.
25 ±2C. 65% RH
85% of adventitious shoots elongated. 8.8 shoots/shoot tip. 85%
rooting after 4 w in soil ?manure (1:1) (survival NR)
Vipranarayana et al. (2012)
MS, WPM or B
5
?
4–12 lMBA?
0.5–2 lM NAA (SIM).
25–2500 mg/l IBA pulse
treatment 12 h ?MS
?0.5 lM IBA (RIM). pH
5.8. 3% sucrose. 0.01%
myo-inositol. Gelling
agent NR
16-h PP. CWFT.
1220 lx. 23 ±2C.
60% RH
80% survival from immature cuttings when surface sterilized with
15% Clorox
for 10 min. 0.1% AC with WPM was best
interaction. No significant difference in interaction between
media and explant type. Maximum number of shoot buds
(-4.95)/cotyledonary nodal explant on B
5
medium
supplemented with 8 lM BA and 2 lM NAA. Longest roots in
25 mg/L pulse treatment. Ex vitro rooting using 1000 mg/L IBA
produced 40% rooting. Acclimatization performed in sand ?
coir dust (1:1) was 80% when kept in humid conditions and weak
light for the first 4 w then for 6 w in greenhouse
Warakagoda and Subasinghe (2013)
Red sandalwood (Pterocarpus santalinus L. f.): biology, importance, propagation and751
123
Conclusions and future perspectives
This review highlights key advances in the tissue culture-
based biotechnology of economically important Pterocar-
pus santalinus. To date, effective protocols for seed surface
disinfection and in vitro germination exist. There are also
effective protocols for direct shoot regeneration from a
range of explants or through callus induction. In most
cases, explants are derived from seeds or seedlings which
are not suitable for clonal propagation (Table 1). There-
fore, a clonal method should be developed from vegetative
tissues of elite germplasm. Rooting and survival of
micropropagated plants remain a major limitation to the
success of P. santalinus tissue culture and should be opti-
mized in the future, for example by using CO
2
enrichment
and vessels that allow for maximized aeration without
impacting relative humidity levels within the culture vessel
(Teixeira da Silva et al. 2005). The ability to stably pro-
duce units that allow for germplasm conservation would
then stimulate the need for cryoconservation (Teixeira da
Silva and Engelmann 2017; Bi et al. 2017), including
through the application of synthetic seeds (Sharma et al.
2013). Analytic hierarchy, which is a multicriteria deci-
sion-making tool, is valuable for incorporating the per-
ceptions of stakeholders when planning the conservation
and restoration of a P. santalinus population (Kukrety et al.
2013a,c). The micropropagation and biotechnology of
another commercially important tree in this genus, P.
marsupium (Indian kino tree), have recently been reviewed
(Teixeira da Silva et al. 2018).
Acknowledgements The authors thank Dr. Emilia Caboni (Agri-
cultural Research Council (CRA), Fruit Tree Research Centre, Rome,
Italy), Dr. Randall Niedz (U.S. Department of Agriculture, Agricul-
tural Research Service, U.S. Horticultural Research Laboratory, FL,
USA) and Dr. Ivana Gribaudo (Istituto Protezione Sostenibile delle
Piante—CNR, Grugliasco, Italy) for ideas, comments and suggested
improvements to an early version of the manuscript. The authors also
thank Prof. M.N.V. Prasad (Department of Plant Sciences, University
of Hyderabad, India) for some suggestions on a later version of the
manuscript.
Open Access This article is distributed under the terms of the
Creative Commons Attribution 4.0 International License (http://crea
tivecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided you give
appropriate credit to the original author(s) and the source, provide a
link to the Creative Commons license, and indicate if changes were
made.
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Culture medium, PGRs,
additives, subcultures
Culture conditions
a
Experimental outcome, maximum productivity, acclimatization
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... The P. santalinus, commonly called 'Red Sandalwood' or 'Red Sanders', is an endangered endemic species of the southeastern part of the Indian peninsula (Soundararajan and Joshi 2012; Bhagyaraj and Ramana 2013;Ramabrahmam and Sujatha 2016;Barstow 2018). The species is highly valued, nationally, and internationally, for its exceptionally distinctive timber quality with a wavy grain texture and suffused with 16% of a red color dye santalin (Rao and Raju 2002; Teixeira da Silva et al. 2019). The wood of P. santalinus costs approximately Rs 30-100 lakhs/ tonne among importers, such as China, Japan, and Myanmar, where it has been used to make high-quality furniture and musical instruments (Soundarajan et al. 2016;Bhagyaraj 2017). ...
... The micropropagation mastered the drawback of conventional vegetative propagation (Prakash et al. 2006; Teixeira da Silva et al. 2019). The technique was first applied in 1960 when George Morel attempted to commercialize orchids (Bhatia and Sharma 2015). ...
... The technique was first applied in 1960 when George Morel attempted to commercialize orchids (Bhatia and Sharma 2015). Since then, it has opened a new way of vegetative propagation with much elaborate efficiency in many species with promises in red sanders (Vipranarayana et al. 2012;Warakagoda and Subasinghe 2013; Teixeira da Silva et al. 2019). In P. santalinus, complete plant regeneration at a large scale was reported through organogenesis and, to some extent, by callogenesis. ...
Article
A micropropagation is a powerful tool in the era of the biotechnology revolution. It has a broad range of potentiality as compared to conventional vegetative propagation attracting researchers, industrialists, governmental and nongovernmental organizations at the national and international level. The potential methods of organogenesis and somatic embryogenesis, primarily through callogenesis, allow the production of genotypically identical and pharmacologically conserved disease-free healthy stocks in shorter times. Pterocarpus santalinus, the pride of Andhra Pradesh, has become endangered due to medicinal and commercial overexploitation. The micropropagation of P. santalinus poses many cultural challenges due to limited regeneration potential through callogenesis, organogenesis, and somatic embryogenesis. The lack of proper explant treatment and the effect of plant growth regulators limit the application of published protocols to reproduce the results. The challenge, such as heavy contamination of mature explants with endophytic fungi, forced us to explore the potential of immature tissues for regeneration through induction of somatic embryogenesis. We observed that immature tissues (zygotic embryo, petal, ovary, and anther) are better responsive than mature tissues with the scantiest contamination and phenolic release. The present study analyzed, evaluated, and interpreted the different parameters applied in the micropropagation of P. santalinus. The aim is to solve the discrepancies of existing protocols to present complete insight for future needs in the successful regeneration of the species. The review also compared various treatments to overcome dormancy and promote germination. It also discussed the possibilities of induction of somatic embryogenesis for future research.
... The ayurvedic medicines are well documented and officially recognized in the form of a traditional system of medicines in India. The system describes the medicinal plant, plant part, mode of preparation, and uses for the treatment, cure, or mitigation of specific diseases either alone or in combination with other herbs (Ravishankar and Shukla, 2007; Teixeira da Silva et al., 2019). ...
... The common name of the plant, red sandalwood or rakt chandan, is grounded on the red-colored elegant heartwood owing to the presence of pigments. The plant has massive medicinal and commercial values due to its red elegant wood for furniture making, handicrafts, and carvings and thus traded illegally (Arunakumara et al., 2011;Bulle et al., 2016c;Teixeira da Silva et al., 2019). Due to its overexploitation and illegal trade, once it was classified as endangered, nevertheless continuous efforts for conservation and cultivation led it to be reclassified as near threatened (https://www. ...
... In Andhra Pradesh, it is mainly distributed in the Kadapa, Chittoor, Kurnool, Prakasam, and Nellore districts, while its distribution in the Tamilnadu is restricted to the Vellore and Chengalpattu districts. In the last few decades, it has been introduced to other parts of the country like Karnataka, Kerala, West Bengal, etc. Few reports suggest the introduction of this plant species in Sri Lanka, China, Taiwan, and Pakistan; the wild status or natural presence in these countries requires further verification (Arunakumara et al., 2011;Bulle et al., 2016c;Pullaiah, 2019;Rao and Raju, 2002;Teixeira da Silva et al., 2019). ...
Article
Ethnopharmacological relevance: Pterocarpus santalinus, an ancient folk medicine, is endemic to the eastern ghats of south India, and the heartwood is prescribed since time immemorial for the mitigation of inflammatory disorders in traditional practice and ayurvedic system of medicines. Aim of the study: This review aims to provide collective pieces of information of the traditional uses, phytochemicals, and pharmacological facets of P. santalinus, with an intuition for promoting future research to explore its pharmaceutical potential as a therapeutic agent against modern maladies. Material and methods: Extensive literature search was performed to collate the data by using various electronic search engines. A network pharmacology-based approach is incorporated for validation of traditional claims orbiting around anti-inflammatory properties and directed its future exploration against obesity, ovarian inflammation, ovarian folliculogenesis, and inflammatory breast cancer. Results: In a nutshell, the present review encompasses the phytochemistry, pharmacology of this species intending to sensitize the scientific community for future research on this promising plant. Nearly 85 chemical constituents are reported from the plants wherein bark and leaves are enriched with the lupane and oleanane class of triterpene while sesquiterpenes and polyphenolic compounds are predominantly present in the heartwood of the plant. Although phytochemical investigations are being reported since the mid-twentieth century however there has been recent interest in the evaluation of biological activities such as anti-inflammatory, anti-oxidant, anti-cancer, anti-viral, etc. CONCLUSION: In conclusion, a systematic phytochemical analysis and pharmacological exploration in close collaboration for establishing the therapeutic potential of the chemical constituents present in P. santalinus is recommended to substantiate the traditional claims for bringing it into the mainstream pharmaceutical and commercial utilization.
... Dalbergia is endemic to tropical and subtropical regions of Asia, Africa, and the Americas, and is commonly used for furniture, musical instruments, handicrafts, and medicine (Ruffinatto and Crivellaro 2019;Wick 2019). All Dalbergia species were listed in CITES Appendix II at CoP 17 in 2016, except Dalbergia nigra, which was previously listed in CITES Appendix I. Pterocarpus is also distributed in tropical areas and P. santalinus, P. erinaceus, and P. tinctorius are listed in CITES Appendix II due to their over-exploitation for furniture, musical instruments, and high-grade decorative materials (Da Silva et al. 2019;Dumenu 2019). Cedrela has 17 recognized species distributed from Mexico through Central America and into northern South America (Pennington et al. 2010) and Cedrela spp. ...
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Due to increasing global trade of timber commodities and illegal logging activities, wood species listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) appendices are facing extinction, and their international trade has been banned or is under supervision. Reliable and applicable species-level discrimination methods have become urgent to protect global forest resources and promote the legal trade of timbers. This study aims to discriminate CITES-listed species from their look-alikes in international trade using quantitative wood anatomy (QWA) data coupled with machine learning (ML) analysis. Herein, the QWA data of 14 CITES-listed species and 15 of their look-alike species were collected from microscope slide collection, and four ML classifiers, J48, Multinomial Naïve Bayes, Random Forest, and SMO, were used to analyze the QWA data. The results indicated that ML classifiers exhibited better performance than traditional wood identification methods. Specifically, Multinomial Naïve Bayes outperformed other classifiers, and successfully discriminated CITES-listed Pterocarpus species from their look-alike species with an accuracy of 95.83%. Furthermore, the discrimination accuracy was affected by the combinations of wood anatomical features, and combinations with fewer features included could result in higher accuracy at the species level. In conclusion, the QWA data coupled with ML analysis could unlock the potential of wood anatomy to discriminate CITES species from their look-alikes for forensic applications.
... Using modern biotechnological tools to preserve the germplasm of plants is the only viable strategy that could save species from becoming extinct; this could be achieved through seed banks or by maintaining live collections by vegetative propagation or plant tissue culture (Reed 2011;Kovalchuk et al. 2008;Wang et al. 2018). Micropropagation has been used for large-scale cultivation as well as for the conservation of rare and endangered plant species (Rani and Raina 2000;Grigoriadou et al. 2019;Kher et al. 2021;Teixeira da Silva et al. 2019;Vasava et al. 2018;Kher et al. 2016). Compared to other regeneration methods used in micropropagation, direct shoot induction is more advantageous than indirect organogenesis in that multiple microshoots can be obtained from the apical and axillary meristems of a mature tree, allowing healthy clones to be propagated; such clones retain their identity with the parental plant and therefore are best suited for micropropagation of rare and endangered species (Chokheli et al. 2020;Gonzalez-Benito and Martín 2010). ...
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Traditional cultivation methods used for domestic apples are not effective when applied for cultivation of the vulnerable wild apple Malus sieversii. However, this apple can be effectively grown using micropropagation, which is an established ex situ conservation tool. The study aimed to grow in vitro M. sieversii cultures using axillary buds as explant. To optimize the media and plant growth regulator combinations for successful in vitro culture, three different media were used: Quoirin and Lepoivre (QL), woody plant medium (WPM), and Murashige and Skoog (MS) containing four different concentrations of 6‑benzylaminopurine (BAP) combined with 0.2 mg/l or 0.5 mg/l of gibberellic acid (GA). Different concentrations of indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA) added to half-strength QL medium were used for optimizing the rooting medium. The combination of QL medium with 1.5 mg/l BAP and 0.01 mg/l IBA resulted in 100% shoot regeneration. The number of shoots (17.20 ± 0.64) and shoot length (2.80 ± 0.10 cm) were greatest when QL medium with 0.75 mg/l BAP and 0.2 mg/l GA was used. One hundred percent root development with the greatest number of roots per explant (8.13 ± 0.44) and longest root length (3.77 ± 0.23 cm) were achieved when half-strength QL medium with 0.5 mg/l of IBA was used. Simple sequence repeat analysis confirmed the reliability of this protocol for efficient large-scale micropropagation of M. sieversii. Through this study, an efficient micropropagation protocol that can be used for large-scale cultivation as well as germplasm conservation of M. sieversii was developed.
... The extract helps to kill a wide range of gram-positive and gram-negative bacteria (Keshavamurthy et al. 2018). Further, the tree has substantial national and international market demand for its rare extraordinary high timber constitution that contains 16% santalin dye (Rao and Raju 2002;Teixeira da silva et al. 2019). Because of its high medicinal and commercial value and endemic to the Southeastern ghats of the Indian peninsula, P. santalinus is known as 'The Pride of Eastern Ghats. ...
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Pterocarpus santalinus is an endangered species with high therapeutic and commercial value that needs urgent protection. The study developed an easy and notable protocol for in-vitro regeneration via callus formation of the species using cotyledons from germinated immature zygotic embryos. The effect of plant growth regulators on callogenesis and morphogenesis was studied. Our investigation demonstrated that maximum callus mass (1036.44 mg) was obtained when Murashige and Skoog (MS) medium were supplemented with 0.1 mg/l BAP and 8 mg/l NAA. However, maximum callus frequency (95.37%) was obtained with 0.1 mg/l BAP and 1 mg/l 2,4-D. For shoot morphogenesis, 0.1 mg/l BAP and 1 mg/l 2,4-D showed a maximum shoot frequency of 83.33%, whereas the maximum number of shoots/explants (1.87) was observed in 0.1 mg/l BAP or 4 mg/l NAA and maximum shoot length (4.12 cm) was found in 0.01 mg/l BAP. The root morphogenesis was found efficient with NAA applied alone or in combination. The combination of NAA (2 mg/l) and BAP (0.01 mg/l) was found efficient for maximum root frequency (83.33%), while maximum roots/explant (8.70) and root length (4.64 cm) were observed in NAA 4 and 2 mg/l respectively. The regenerated plantlets survived well in the acclimatization process for 3–5 weeks but grew slowly. The plantlets that survived in the laboratory condition got through the greenhouse with a 100% survival rate. The control of various morphogenetic processes as a function of growth regulators has been discussed. Hence, the present study can be applied to the large-scale propagation of species to improve their population.
... The irrigation to plants is done immediately after transplantation. Further, alternate days up to 15 days irrigation are done [4]. Table 1 classifies and enlists the phytoconstituents of P. santalinus [8][9][10]. ...
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The review provides an updated overview of the phytochemical and pharmacological studies on Pterocarpus santalinus. It briefs on the synergistic interactions of P. santalinus with other medicinal plants and its use in Ayurvedic formulations. Phytochemical analysis suggests the presence of triterpenoids, steroids, flavonoids, and phenolic acids. The phytoconstituents and related pharmacological activities of various parts of P. santalinus include antifungal, anticholinesterase, antidiabetic, antibacterial, antipyretic, anti-inflammatory, anticancer, and antiulcer. Literature survey highlights the dermatological applications of the phytoconstituents such as pterostilbene, savinin, and betulin as potential leads for anti-aging, ultraviolet rays (UV-B) protective, and wound healing effects. Undoubtedly, P. santalinus has wide therapeutic value. The dermatologically significant phytoconstituents, namely, pterostilbene, cedrol, savinin, lupeol, betulin, β-eudesmol, and α-bisabolol, if isolated and used in dermatological formulations, can show promising skin protective effect. The data were compiled using scientific databases, namely, Google Scholar and PubMed, the data made available specifically from 2010 to 2021.
... Micropropagation can serve as an effective method for the large-scale clonal propagation of plants, and the foundation for in vitro manipulation of plants via genetic engineering for trait improvement, cryoconservation, and secondary metabolite production (Cardoso et al. 2018). To successfully establish a micropropagation protocol of a tree species, various factors need to be optimised: Explant choice (based on genotype, age of the mother tree, management of stock plants/mother plant, season and timing of explant collection, surface disinfection of explant, explant size, length/diameter and orientation, explant media ratio and density), the type and concentration of macro-and micronutrients, organic supplements, and plant growth regulators (PGRs), additives (ascorbic and citric acids, polyvinylpyrrolidone, activated charcoal, adenine sulphate, L-arginine, glutamine, ammonium citrate), vessel type, light source, type and intensity and photoperiod, medium pH, disinfection method, acclimatization conditions, including substrate choice (Shekhawat et al. 1993;Kher et al. 2016;Teixeira da Silva et al. 2016a, b, 2018, 2019Vasava et al. 2018). Close examination of the D. latifolia tissue culture literature reveals that most of the studies lack information about one or more of these essential parameters (Tables 1 and 2), which may reduce the reproducibility of such studies, thereby hampering the large-scale production of D. latifolia. ...
Article
Dalbergia latifolia Roxb. (Fabaceae), famed for its wood, is a vulnerable plant species according to the International Union for Conservation of Nature and Natural Resources (IUCN) Red List as a result of its over-utilisation. This mini-review, which provides a synthesis of the micropropagation of this woody plant species, can be useful for the establishment of a more focused and comprehensive micropropagation protocol. An in-depth analysis of previously published reports indicates that the most commonly employed explant in D. latifolia in vitro regeneration protocols are seedling-derived explants such as cotyledonary nodes since the use of ex vitro material leads to considerable contamination and phenolic oxidation. The media composition for culture initiation, multiplication, maintenance and rooting has been thoroughly studied but in most studies, pertinent information about acclimatization and plant survival in the field was not provided, reducing the reproducibility of protocols. This mini-review provides possible solutions to overcome explant contamination and browning during D. latifolia in vitro culture establishment.
... Due to limitations arising from conventional plant propagation methods through seeds (such as viability and increased chances of seed borne diseases) and by vegetative means (such as increased risks of disease transmission to propagules from mother stock and production of a limited number of plants), there is need for an alternate method for large-scale propagation of this plant. Micropropagation plays a crucial role not only in meeting conservation needs but also in supplying quality medicinal plant stock to meet growing pharmaceutical demand (Teixeira da Silva et al., 2019;Komakech et al., 2020). In vitro propagation is known to be more effective for the rapid multiplication of plants than the conventional propagation (Das et al., 2020). ...
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Aspilia africana (Pers.) C. D. Adams is an important medicinal plant, that has been used as traditional medicine in many African countries for the treatment of various health problems, including inflammatory conditions, osteoporosis, tuberculosis, cough, measles, diabetes, diarrhea, malaria, and wounds. We developed an efficient and reproducible protocol for in vitro regeneration of A. africana from nodes. We assessed the effects of plant tissue culture media on A. africana growth, cytokinins for in vitro shoot regeneration and proliferation, and auxins for the rooting of regenerated shoots. Furthermore, chlorophyll content, photosynthetic rates, anatomy (leaves, stems, and roots), and Fourier transform near-infrared (FT-NIR) spectra (leaves, stems, and roots) of the in vitro regenerated and maternal A. africana plants were compared. Murashige and Skoog media, containing vitamins fortified with benzylaminopurine (BA, 1.0 mg/l), regenerated the highest number of shoots (13.0 ± 0.424) from A. africana nodal segments. 1-naphthaleneacetic acid (NAA, 0.1 mg/l) produced up to 13.10 ± 0.873 roots, 136.35 ± 4.316 mm length, and was the most efficient for rooting. During acclimatization, the in vitro regenerated A. africana plants had a survival rate of 95.7%, displaying normal morphology and growth features. In vitro regenerated and mother A. africana plants had similar chlorophyll contents, photosynthetic rates, stem and root anatomies, and FT-NIR spectra of the leaf, stem, and roots. The established regeneration protocol could be used for large-scale multiplication of the plant within a short time, thus substantially contributing to its rapid propagation and germplasm preservation, in addition to providing a basis for the domestication of this useful, high-value medicinal plant.
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P. marsupium in Gwalabari community forest comprises a very small population with lower proportions of seedlings and reproductive individuals and highest proportion of saplings. The loss of reproductive stage indicates intense current harvesting of adults. Therefore, to enhance fitness and ensure long-term viability, the existing population of P. marsupium should be strictly protected from harvesting, overgrazing and other human interferences. Particularly, protection and monitoring of seedlings and adult reproductive trees in the natural habitat is the immediate need for its conservation. Such monitoring should also take into consideration all the ecological factors affecting population fitness. Establishment of a system for sustainable Kino gum extraction is another important aspect to be focused. In addition, complementary approaches, such as augmentation and reintroduction programs are needed to increase the size of the existing populations and enhance its gene pool; and create new populations in the ecologically suitable site within its historical range where the species no longer occurs. Our study also provides some insights about the habitat preferences and other biotic interactions highlighting the significance of the species to the ecosystem
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Trees are vital resources for economic, environmental, and industrial growth, supporting human life directly or indirectly through a wide variety of therapeutic compounds, commodities, and ecological services. Pterocarpus marsupium Roxb. (Fabaceae) is one of the most valuable multipurpose forest trees in India and Sri Lanka, as it is cultivated for quality wood as well as pharmaceutically bioactive compounds, especially from the stem bark and heartwood. However, propagation of the tree in natural conditions is difficult due to the low percentage of seed germination coupled with overexploitation of this species for its excellent multipurpose properties. This overexploitation has ultimately led to the inclusion of P. marsupium on the list of endangered plant species. However, recent developments in plant biotechnology may offer a solution to the overuse of such valuable species if such advances are accompanied by technology transfer in the developing world. Specifically, techniques in micropropagation, genetic manipulation, DNA barcoding, drug extraction, delivery, and targeting as well as standardization, are of substantial concern. To date, there are no comprehensive and detailed reviews of P. marsupium in terms of biotechnological research developments, specifically pharmacognosy, pharmacology, tissue culture, authentication of genuine species, and basic gene transfer studies. Thus, the present review attempts to present a comprehensive overview of the biotechnological studies centered on this species and some of the recent novel approaches for its genetic improvement.
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The present investigation entitled "Effect of different pre-sowing treatments and growing conditions on germination of Red Sanders (Pterocarpus santalinus L. f.)" was carried out in the year 2015-16 at Department of Silviculture and Agroforestry, ASPEE College of Horticulture and Forestry, Navsari Agricultural University, Navsari (Gujarat). The experiment comprised of eleven pre-sowing treatments viz., T1 (Tap water for 4 days), T2 (Tap water for 8 days),T3 (Lukewarm water for 4 days), T4 (Lukewarm water for 8 days), T5 (GA3 @ 250ppm for 1 day), T6 (GA3 @ 500ppm for 1 day), T7 (10 % sulphuric acid for 1day), T8 (10 % hydrochloric acid for 1day), T9 (10 % nitric acid for 1day), T10 (Separating seeds from pods with a sharp knife or scalpel and sown directly) and T11 (Control) and grown in net house condition with Completely Randomized Design having three repetitions. The treated plants were kept in net house for further study. Among different pre-sowing treatments, seed pre-treated with T6 (GA3 @ 500ppm for 1 day) registered earlier sprouting (7.67) and higher germination percentage (66.67 %), collar diameter (5.65 mm), plant height (41.20 cm), number of leaves per plant (20.44), root length (30.57 cm), fresh of plant (31.58 g/plant), dry weight of plant (24.77 g/plant) and survival percentage (63.33 %). The next best pre-sowing treatments are T5 (GA3 @ 250 ppm for 1 day) and T10 (Separating seeds from pods with a sharp knife or scalpel and sown directly). The seeds which were no treated (T11: control) found poorest for all parameters under study.
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Te 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. Te 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 confrm the genetic stability of in vitro-propagated material. Biotechnological advances for this leguminous tree of commercial importance would beneft 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.
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Pterocarpus santalinus is a highly valued medium-sized leguminous endemic tree with a restricted range in the southern Eastern Ghats deciduous forests. The enumeration in four 1ha plots has yielded a total of 878 Red Sanders tree individuals (≥30cm girth at breast height - gbh) with a range of 165–246 individuals per ha and 9–51 individuals per 0.01ha. The size class structure revealed that the majority of individuals occurred in lower gbh classes with 364 individuals (39.5%) in 30–50 cm gbh class and 420 individuals (45.6%) in 51–70 cm gbh class, while in the higher gbh class (71–90 cm gbh) only 129 individuals (14%) and seven individuals in >90cm gbh class were recorded. Overall the population structure indicated a low ratio change in lower gbh classes suggesting a stable population. A higher percentage of life stages in recruitment stage like seedlings and saplings than trees was observed and the feature of re-sprouting from roots after fire damage was also recorded. A bottleneck progress from regenerating trees to adult trees was noticed, may be due to slow growth of the species. High stem density and presence of individuals in all the regenerating and reproductive classes suggest that Red Sanders is tolerant to mild disturbance. But the drastic reduction in the density in higher gbh class reflects the concern for recruitment in future as it may affect the seed output due to loss of reproductively fit mature trees.
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Pterocarpus santalinus Linn. commonly known as Red Sandalwood belongs to the family Fabaceae. It is is used in India and other parts of the world, with illegal harvest being a key threat. The plant is renowned for its characteristic timber of exquisite color and beauty. The Red Sandalwood has natural dye i.e santalin, which is used as coloring agent in pharmaceutical preparations and foodstuffs. In the traditional system of medicine, the decoction from the heartwood is attributed various medicinal properties. It is used in ulcers, eye diseases, inducing vomiting and mental aberrations. The heartwood is known to have antihyperglycaemic activity, antipyretic, antiinflammatory, anthelmintic, tonic, hemorrhage, dysentery, aphrodisiac, diaphoretic activities and also used as a cooling agent. It has been reported that wood in combination with other drugs is prescribed for snake bites and scorpion stings. Phytochemical studies of this plant indicate that it contains substances such as alkaloids, phenols, saponins, glycosides, flavonoides, triterpenoides, sterols and tannins. In addition, heart wood contains isoflavone, glucosides and two antitumour lignans, viz., savinin and calocedrin. This review explores the phytochemical and pharmacological effects of the Pterocarpus santalinus Linn and compiles vital information that may assist researchers on what is known about this plant for further investigation. However, the species has remained unexplored for many pharmacological activities claimed. Hence, the present paper reviewed about phytochemical, pharmacological and medicinal uses of Pterocarpus santalinus Linn.
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The successful ex vitro establishment of Dendrobium plantlets raised in vitro determines the quality of the end product (cut flowers or potted plants) in commercial production for economic gain. When in vitro Dendrobium plantlets are transplanted from the culture room to greenhouse conditions, they may desiccate or wilt rapidly and can die as a result of changes in the environment, unless substantial precautions are taken to adapt plantlets to a new environment. The acclimatization of in vitro-grown Dendrobium plantlets to an ex vitro environment by gradually weaning them towards ambient relative humidity and light levels facilitates better survival of the young and physiologically sensitive plantlets. Dendrobium plantlets raised in vitro must thus undergo a period of acclimatization or transitional development to correct anatomical abnormalities and to enhance their physiological performance to ensure survival under ex vitro conditions. The most common approach to improve the survival of Dendrobium plantlets upon transfer to an ex vitro environment is their gradual adaptation to that environment. Under such conditions, plants convert rapidly from a heterotrophic or photomixotrophic state to an autotrophic growth, develop a fully functional root system, and better control their stomatal and cuticular transpiration. Gradual adaptation is carried out in a greenhouse by decreasing relative humidity using fog or mist chambers and by increasing light intensity using shading techniques. This review details the acclimatization and ex vitro survival of Dendrobium plants produced in vitro. This advice is also useful for other orchids.
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Grapevine (Vitis genus) is one of the economically most important fruits worldwide. Some species and cultivars are rare and have only a few vines, but represent national heritages with a strong need for preservation. Field collections are labour intensive, and expensive to maintain, and are exposed to natural disasters. In addition, infection with pathogens, especially viruses, is common in grapevine because of vegetative propagation, which is conventionally used for this genus. Cryopreservation provides an alternative and ideal means for the long-term preservation of Vitis germplasm, which can be used as a backup to field collections for important autochthonous cultivars or only as cryo-banks for rare, native cultivars that are worthy of preservation. Cryotherapy, based on cryopreservation protocols, provides an efficient method for the eradication of grapevine viruses. This review provides comprehensive and updated information on cryopreservation for long-term preservation of genetic resources and cryotherapy for virus eradication in Vitis. Additional research in grapevine cryopreservation and cryotherapy is needed.
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Oil palm (Elaeis guineensis Jacq.), a tropical plant, is the leading source of edible oil. This review deals with the cryopreservation of oil palm as a way to preserve this important tropical germplasm. Somatic embryos have been the most popular source of material for cryopreservation as they are propagules that are effectively produced during micropropagation. In contrast, fewer studies exist on the cryopreservation of pollen, zygotic embryos, seeds, kernels and embryogenic cell suspensions. This review highlights the ideal protocols, in detail, in a bid to offer guidance for further advances in oil palm cryopreservation.
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Pterocarpus santalinus L. f. (Red Sanders) is narrowly endemic to the Seshachalam, Veligonda, Lankamala and Palakonda hill ranges in Andhra Pradesh. The wood and wood products of Red Sanders continue to be in high demand and are traded internationally in large volumes that find use in the musical instruments, furniture, handicrafts, cosmetics, medicine and food industry. Over exploitation without commensurate replenishment of natural stands and illegal logging has posed a severe threat to the very existence of this precious timber species and classified as globally threatened in the IUCN Red List. Good-quality heartwood of Red Sanders is illegally traded and fetches very high price in the global market. As harvest of heartwood from natural population may not be sustainable, any future plan of harvest of Red Sanders wood and export should be from cultivated sources. About 5000 ha of plantations of Red Sanders exists in various states in South India. Little information is available about the quality and quantity of heartwood formation in plantations compared to natural populations. In this backdrop, the current study was conducted to evaluate the variation in heartwood, sapwood and bark content, and wood density of plantation-grown Red Sanders trees of various age classes located in various places. The core wood samples from various locations were collected using increment borer based on standard sampling procedure. The heartwood, sapwood and bark content were measured as a percentage of the cross-sectional area at breast height. Wood density was determined using core wood samples taken at breast height of the tree. The variation in heartwood content and wood density of Red Sanders were found to be influenced by the age and size of the trees.