1022-7954/04/4002- © 2004
Russian Journal of Genetics, Vol. 40, No. 2, 2004, pp. 152–159. From Genetika, Vol. 40, No. 2, 2004, pp. 210–217.
Original English Text Copyright © 2004 by Chatterjee, Vijayan, Roy, Nair.
India is the only country, which commercially
exploits the semi-wild sericigenous lepidopteran insect
. The major amount of its cocoon is
collected by forest dwellers (Fig. 1a) from different
areas of the tropical forests (76
the states of West Bengal, Bihar, Jharkhand, Uttaran-
chal, Madhya Pradesh, Chattisgarh, Orissa, Maharash-
tra, and Andhra Pradesh [1–4] and a part of the produce
is also obtained from systematic outdoor rearing of the
larvae on block plantations (Fig. 1b) of
arjuna, T. tomentosa, Hardwicki binata
Surveys conducted in British India identiﬁed this
silk producing wild insect in different forests across the
country, as different species [1, 2, 4, 5]. However, later
on, all these species were bought under
 and different populations of this species are
termed as ecoraces or ecotypes [4, 6, 7].
Many attempts were undertaken to characterize the
“ecotypes” from different parts of tropical forest zones
through conventional methods of genetic analysis ,
biochemical characterization of isozymes [9, 10] and
also through various yarn (silk ﬁber) characters .
However, identiﬁcation of speciﬁc heritable characters,
morphological or physiological, to characterize the dif-
ferent gene pools, was found to be extremely difﬁcult as
these characters revealed drastic changes in different
seasons. This is the most important factor that led us to
take up the present study.
Studies with different plant and animal genomes,
showed the suitability of using ISSR (Inter Simple
Sequence Repeat) primers in differentiating cultivars
 or characterizing genetic polymorphism [12–14].
Studies made in this laboratory revealed the usefulness
of ISSR markers in differentiating various stocks of
 as well as its food plants. Hence,
ISSR primers were selected for the present study.
MATERIALS AND METHODS
Genetic materials used.
Randomly selected male
and female pupae from populations representing 11 dif-
ferent zones in the central and northeastern part of India
were used for the ﬁrst part of the study. For the detailed
examination, cocoons of the “Railey” silkworms [16, 17]
from ﬁve different areas coveing a portion of Bastar
Hill and the adjacent plateaus (Fig. 2) were used. These
latter materials were marked as T401, T402, T403,
T404, and T407, respectively for representing the col-
lections from Kondagaon, Nangur, Darba, Tongpal
ISSR Profiling of Genetic Variability in the Ecotypes
Drury, the Tropical Tasar Silkworm*
S. N. Chatterjee
, K. Vijayan
, G. C. Roy
, and C. V. Nair
SeriBiotech Laboratory, Central Silk Board, Kodathi Campus,
Sarjapur Road, Carmelram, Bangalore 560035, Karnataka, India;
Central Tasar Research & Training Institute, Piska-Nagri, Ranchi-835303, Jharkhand, India
Received March 4, 2003
Drury, the semi-wild silk-producing lepidopteran insect commonly known as
tasar silkworm is unique to India and is distributed over a wide tropical forest range covering the states of
Andhra Pradesh, Bihar, Chhattisgarh, Madhya Pradesh, Maharashtra, Orissa, and Uttaranchal. The populations
found in different areas are know by their speciﬁc local names and are considered as different ecotypes, but it
is difﬁcult to separate the populations on the basis of morphological and life-cycle traits and thus molecular
characterization was attempted. The present communication relates to the results obtained from the analysis of
polymorphism unraveled by twelve ISSR primers for 11 populations of
belonging to six ecotypes and
41 individuals of Railey ecotype collected from ﬁve zones of Dandakarnya forest in Madhya Pradesh. This
communication, further, presents molecular evidences on genetic differences between eleven ecotype popula-
tions and highlights the genotypic diversiﬁcation of a single ecotype into further separate discrete gene pools.
The canonical discriminant function analysis revealed grouping of the ﬁve populations of Railey ecotype into
two “clumps,” while accessions of other ecotypes stood separated from each other. The Railey populations on
detailed study, further, revealed separation of two (Tokapal and Nangur) populations into discrete gene pools
and the other three (Kondagaon, Darba, and Tongpal) populations, overlapped in spite of larger geographic dis-
tance between them. The analysis also identiﬁed nine markers, which can be utilized to characterize speciﬁc
population and will be of help to follow the ongoing genetic changes triggered by various ecological factors
and human inﬂuences on the Railey ecotype.
*This article was submitted by the authors in English.