Medicinal plants have been given great
significance in recent years due to its demand in industry for human and animal welfare and alluring market prices
(Lubbe and Verpoorte 2011). India is called as the “Botanical Garden” of the
world due to variegated climatic ecosystem which is suitable for cultivation
for medicinal plants. India being one of the
world’s 12 mega biodiversity countries needs to conserve its resources where
they are being exploited and should be grown commercially to avoid their
susceptibility to extinction because of indiscriminate use.
Among the various medicinal plants, Withania
somnifera (L.) Dunal
(Winter cherry, Ashwagandha or Asgandh of family Solanaceae is an
important medicinal plant that finds extensive use as a potential herb in the
traditional system of medicine as a ‘rasayana’ and ‘medhya rasayana’. The similarities between
roots of Ashwagandha and ginseng roots have led to it being called as Indian
ginseng (Tripathi et al. 1996).
somnifera is a genetically
simple species (2n = 48; n = 24; largely self-pollinated) most suited to
develop cultivars for commercial production of novel sterols and alkaloids
(Singh and Kumar 1998). It grows in dry and sub-tropical regions. The major Ashwagandha cultivating states are
Madhya Pradesh, Rajasthan, Punjab, Uttar Pradesh, Haryana, Gujarat and
Maharashtra among which Madhya Pradesh alone is having more than 4000 ha area
for cultivation. Its roots, leaves and seeds are used in preparation of
Ayurvedic and Unani medicines, to combat a wide range of diseases from
tuberculosis to arthritis. In the plant, important part is roots, leaves and
berries because they contain alkaloids called as “Withanolides” (Gupta et al.
major biochemical constituents of W. somnifera are steroidal alkaloids and
lactones, a class of constituents together known as withanolides (steroidal
lactones with ergostane skeleton).
Ongoing trials and research on animal support the
role of ashwagandha’s root and leaf extracts in different disorders and
diseases and possess properties like anticancer, antioxidant etc. (Chopra et
al. 2004; Cooley et al. 2007; Murthy et al. 2010; Rasool et al. 2000;
Padmavathi et al. 2005; Bhattacharya et al. 2006) and act as source of a
restorative drug (Asthana and Raina 1989). There is no influence of environment on molecular markers and that is the
reason for their wide application in genetic diversity assessment among W.
somnifera (L.) Dunal genotypes
and to identify duplicated accessions within the germplasm collections. Most important development has occurred in the
field of molecular genetics with the emergence of molecular marker. These
markers are used for the detection and exploitation of DNA polymorphism (Semagn
et al. 2010).
DNA markers are unaffected by physiological
conditions and environmental factors thus reliable for informative
polymorphisms since genetic composition is unique for each species. Molecular
markers have provided a powerful new tool for breeders to search for new
sources of variation and to investigate genetic factors controlling quantitatively
inherited traits. Genetic polymorphism helps in distinguishing plants at inter-
and/or intra-specific level not only in medicinal plants but also in cereals,
cash, plantation and horticulture crops.
most important role of conservation is to preserve the process of genetic
diversity and development in the viable population of ecology and commercially
viable varieties / genotypes to avoid possible extinction (Rout et al. 2010). Different
types of marker systems have been used for biodiversity analysis. These include
RFLP, SSR, RAPD and the AFLP. RAPD
markers are two molecular approaches that have been used to detect variation
among plants. Systematic
evaluation and quantification of the variability from the present study will
serve as one step towards providing accurate genetic information for further
breeding programmes for Withania
improvement. The assessment of variation would provide us a
correct picture of the extent of variation, further helping us to improve the
genotypes for biotic and abiotic stresses. The main objective of this study was to characterize
the Withania genotypes using
morphological and molecular markers in order to evaluate the genetic diversity
and relationships among genotypes lines.