Medicinal Plant Research 2015, Vol.5, No. 6, 1-9
1
Research Article
Open
Access
Effect of arsenic on trichome ultrastructure, essential oil yield and quality
of
Ocimum basilicum
L.
Biswas S.
1
, Koul M.
2
, Bhatnagar A.K
1
1.Department of Botany, University of Delhi, Delhi – 110 007, India
2.Department of Botany, Hans Raj College, University of Delhi, Delhi – 110 007, India
Corresponding
authors
email:
Medicinal Plant Research,
2015,
Vol.5,
No.6
doi: 10.5376/mpr.2015.05.0006
Received:
07
Jun.,
2015
Accepted:
15
Jul.,
2015
Published:
0
7
Aug.,
2015
Copyright
© 2015 Biswas., Koul M., Bhatnagar A.K.,
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Biswas S., Koul M., Bhatnagar A.K., 2015,
Effect of arsenic on trichome ultrastructure, essential oil yield and quality of
Ocimum basilicum
L., Medicinal Plant
Research,
5(6):
1
-
Abstract
An experiment was carried out to study the effect of various arsenic (As) treatments on growth, essential oil (EO) yield,
composition of oil and morphology and ultrastructure of glandular trichomes of
Ocimum basilicum
(sweet basil) an important EO
yielding plant. As in the form of disodium hydrogen arsenate [Na2HAsO4.7H2O] was added in the soil in the range of 0, 10, 50, 150
mg/kg As. As stress caused reduction in growth and biomass of shoot system at 50 and 150 mg/kg As. EO yield increased by 3.5-4
times at 10 and 50 mg/kg As, but decreased significantly by 0.08% at 150 mg/kg As. GC analysis revealed that linalool the main EO
compound present in the leaves augmented 3 to 4 times under 10-150 mg/kg As as compared to control. Other compounds such as
1,8-cineol and methyl eugenol decreased with increased As treatments whereas methyl cinnamate was not detected at 50 and 150
mg/kg As in chromatographs. Camphor did not appear in any of the As treated plants. Light microscopic studies and electron
micrographs revealed that As stress affected glandular trichome morphology and ultrastructure. Premature senescence was observed
in trichomes of leaves at 150 mg/kg As and noticeable changes were observed in cell organelles of secretary cells. A positive
correlation between EO yield and trichome density was observed in the present study.
Keywords
Arsenic; Essential oils;
Ocimum basilicum;
trichomes
1.
Background
Contamination of soil with As and As-containing
salts is a global environmental problem. As-based
pesticides, fertilizers, metal processing industries
and coal combustion units are some of the main
sources of As pollution (Meharg and Whitaker, 2002;
Liao et al., 2004). Pollution of groundwater with As is
increasing at an unprecedented rate in some South
Asian countries, especially Bangladesh and India
(Ghosh et al., 2006). Irrigation of agricultural fields
with As polluted water has significantly increased As
levels in soil (Marin et al., 1992). Consumption of
food grown in As-contaminated soil causes many
health problems such as cancer, cardio-vascular
disease and neurological disorders (Gadepalle et al.,
2008). As polluted water has the potential to cause
severe skin allergies, dermatological lesions and other
health related problems.
Persistence of As in the environment for long duration
is resulting in decrease in yield and quality of many
important agricultural crops (Rashid et al., 2004). As
is taken up from the soil by plant roots and is
transferred to higher trophic levels via food chain
(Zhang et al., 2002). Experiments carried out on
a variety of crop species have demonstrated that As
contamination in soil causes adverse effects on plant
biomass productivity and yield (Carbonell-Barrachina
et al., 1997). As uptake by plants and its effect on
plant nutrition has been investigated in detail for
various species such as
Brassica
juncea
,
Oryza sativa
,
Pteris vittata
and
Spartina alterniflora
(Carbonell et
al., 1998; Abedin and Meharg, 2002; Chaturvedi, 2006;
Fayiga et al., 2007).
EO yielding plants are important cash crops and are
sources of bioactive constituents that have medicinal
value. These plants are considered to be hardy and
grow safely on metal-polluted soils around smelters
and soil contaminated with heavy metals (Zheljakov
and Nielsen, 1996; Salamon, 2008). Studies conducted
on some important medicinal plants such as
Bidens
tripartite
,
Leonurus cordiaca
,
Marrubium vulgare
,
Melissa officinalis
and
Origanum heracleoticum
clearly depict that no severe phytotoxic symptoms
were observed in morphology, EO percentage and
