The Crown gall tumour assay (CGTA) is one of several bench top bioassays recommended for the rapid screening of plants with anti-cancer activity. The rationale for the use of the bioassay is that the tumorogenic mechanism initiated in plant tissues by _Agrobacterium tumefaciens_ is in many ways similar to that of animals.  Several plant species with anti-cancer activity have already been discovered using this bioassay.  However till date no explicit test of an association between anti-cancer activity of plants and their resistance to crown gall formation has been demonstrated. Demonstration of an association could have exploratory potential when searching for plants with anti-cancer activity. In this paper, we determined whether or not a statistically significant association between crown gall resistance and anti-cancer activity exists in plants found in existing published data sets.   Our results indicate that plants with anti-cancer activity have a higher proportion of their species resistant to crown gall formation compared to a random selection of plants. We discuss the implications of our results especially when prospecting for newer sources of anti-cancer activity in plants

BT. Ramesha

G. Ravikanth

KN Ganeshaiah

R Srirama

R. Uma Shaanker

English

Nature Precedings

Are plants with anti-cancer activity resistant to crown gall? : A test of hypothesis

The Crown gall tumour assay (CGTA) is one of several bench top bioassays recommended for the rapid screening of plants with anti-cancer activity. The rationale for the use of the bioassay is that the tumorogenic mechanism initiated in plant tissues by Agrobacterium tumefaciens is in many ways similar to that of animals. Several plant species with anti-cancer activity have already been discovered using this bioassay. However till date no explicit test of an association between anti-cancer activity of plants and their resistance to crown gall formation has been demonstrated. Demonstration of an association could have exploratory potential when searching for plants with anti-cancer activity. In this paper, we determined whether or not a statistically significant association between crown gall resistance and anti-cancer activity exists in plants found in existing published data sets. Our results indicate that plants with anti-cancer activity have a higher proportion of their species resistant to crown gall formation compared to a random selection of plants. We discuss the implications of our results especially when prospecting for newer sources of anti-cancer activity in plants

Srirama, R

Ramesha, BT

Ravikanth, G

Uma Shaanker, R

Ganeshaiah, KN

ePrints@ATREE

SCIENTIFIC CORRESPONDENCE 
 
CURRENT SCIENCE, VOL. 95, NO. 10, 25 NOVEMBER 2008 1407
Are plants with anti-cancer activity resistant to crown gall?: a test of 
hypothesis 
 
Bioprospecting for plants with anticancer 
activity has been a major focus in the 
search for plant-based cures1. The National 
Cancer Institute (NCI) alone has report-
edly screened over 35,000 plant species 
for anti-cancer activity2–6. Two of the 
three most important anti-cancer com-
pounds available today, namely taxol and 
camptothecin, were the result of this en-
deavour7–9. The screening of a large 
number of plants over dozens of cancer cell 
lines has often been time-consuming5. 
 In an effort to minimize the screening 
process and hasten the pace of drug dis-
covery, the NCI developed a number of 
rapid bench-top bioassays to short-list 
potential plants, which then could be  
targeted for more advanced screening10. 
One of these bench-top bioassays was 
the crown gall tumour assay (CGTA)11. 
Crown gall is a neoplastic syndrome 
caused by Agrobacterium tumefaciens. 
Crown gall is a common disease of dicot 
plants, including many woody shrubs and 
various herbaceous plants12. Infected 
plants exhibit tumorogenic growth symp-
toms in stem collars and other parts of 
the plant. The bioassay, based on this 
disease evaluates the ability of plant ex-
tracts to inhibit tumours induced by A. 
tumefaciens in model systems such as 
potato tuber discs13. The rationale for 
employing this bioassay rests on the fact 
that the tumorogenic mechanism induced 
by A. tumefaciens in plants is in many 
ways similar to that of animals14,15. 
McLaughlin and Rogers16 have shown an 
association between the inhibition of 
crown gall formation on potato discs and 
the in vivo 3PS anti-tumour activity by 
the plant extracts. Accordingly, the use 
of this bioassay has helped in the short 
listing of plants with anti-cancer activity, 
and in the discovery of novel compounds 
from plants10,13,17–19. 
 Thus it appears that plants intrinsically 
resistant to crown gall infection could, in 
principle at least, also be associated with 
anti-cancer activity. A test of prediction 
and demonstration of an association bet-
ween crown gall resistance and anti-cancer 
activity could have immense exploratory 
potential in the search for newer plants 
as sources of anti-cancer activity. 
 Towards this end, we compiled a data-
base of 1193 species (comprised of 588 
genera and 138 families) of dicot plants 
based on their resistance or susceptibility 
to crown gall infection as reported by 
DeCleene and DeLey20. Species were as-
signed a qualitative score of either crown 
gall resistant (+) or susceptible (–), as 
reported by DeCleene and DeLey20. For 
the purpose of this analysis, we used data 
on only those 1110 species for which the 
information was complete. 
 We then compiled a list of 38 plant 
species that were reported to possess 
anti-cancer activity from a variety of pub-
lished sources (Plants for future Data-
base, www.pfaf.org, etc.; supplementary 
information available upon request from 
the authors). All studies sourced here 
were based on either an in vitro or an in 
vivo assay for anti-cancer activity. 
 Based on these two datasets, we per-
formed a contingency chi-square test of 
association between anti-cancer activity 
and crown gall resistance. Ideally, such a 
test would require the setting up of a 
2 × 2 matrix of crown gall (resistance/ 
susceptibility) and anti-cancer activity 
(present/absent) and then statistically 
evaluating the association. Unfortunately, 
because of a well-recognized positive 
bias in publications21,22, papers often only 
report studies where anti-cancer activity 
was observed, seldom publishing studies 
with no activity. Consequently, a 2 × 2 
matrix with data cells corresponding  
to crown gall resistance/susceptibility 
and anti-cancer activity (absence) is defi-
cient, thus limiting the association analy-
sis. 
 Under these circumstances, we analy-
sed the association by generating the ex-
pected frequency distributions for crown 
gall resistance or susceptibility using the 
data from DeCleene and DeLey20. For 
each of the 38 plants, we inferred their 
resistance or otherwise, to crown gall 
from the database assembled from De-
Cleene and DeLey20. We analysed the 
association at both the species and gen-
era level. At both levels, there was signi-
ficant association of crown gall resistance 
and anti-cancer activity (chi-square (at 
species level) = 10.63, P < 0.001; chi-
square (at genera level) = 12.70, P < 0.001; 
Table 1). Further, as against 81% of the 
species resistant to crown gall from those 
that had anti-cancer activity, only 41% of 
the species was resistant from the ran-
dom collection represented by DeCleene 
and DeLey20. 
 Thus, our results indicate that plants 
with anti-cancer activity appear to have a 
higher proportion of species resistant to 
crown gall than randomly selected spe-
cies. Though not as directly demonstra-
tive as would have been desired through 
a 2 × 2 association analysis, our results 
nevertheless provide a useful first step in 
working towards a more robust test of 
the association. 
 Crown gall tumour assay has been in 
vogue as a rapid technique for screening 
for anti-cancer activity in plants. How-
ever, there has not been any explicit test 
of an association between crown gall re-
sistance and anti-cancer activity. Our re-
sults pave the way for the development 
of algorithms that make the search for 
anti-cancer activity in plants in a more 
directed manner. These results seem to 
support the view of Smith23, expressed 
nearly 92 years ago when he stated, ‘It is 
my belief that a diligent study of tumours 
Table 1. Association between resistance or susceptibility of plants to crown gall disease and 
 their anti-cancer activity. Data are provided at both the species and genera level 
 Species Genus 
 
 Observed Expected Observed Expected  
  frequency frequency frequency frequency 
 
Resistant to crown gall 31 21 31 20 
Susceptible to crown gall  7 17  7 18 
Chi-square (at species level) = 10.63, P < 0.001; Chi-square (at genera level) = 12.70, P < 0.001.
Note: Expected frequencies for the cells have been generated based on data given in DeCleene 
and DeLey20 on random collection of plants with resistance or susceptibility to crown gall. 
SCIENTIFIC CORRESPONDENCE 
 
CURRENT SCIENCE, VOL. 95, NO. 10, 25 NOVEMBER 2008 1408 
in plants will help to solve the cancer 
problem’. 
 
 
1. Raskin, I. et al., Trends Biotechnol., 
2002, 20, 522–531. 
2. Cragg, G. M., Boyd, M. R., Cardellina, J. 
H., Newman, D. J., Snader, K. M. and 
McCloud, T. G., Ciba Found. Symp., 
1994, 185, 178–190. 
3. Cragg, G. M., Newman, D. J. and 
Snader, K. M., J. Nat. Prod., 1997, 60, 
52–60. 
4. Douros, J. and Suffness, M., Cancer 
Res., 1980, 70, 21–44. 
5. Douros, J. and Suffness, M., Cancer 
Res., 1981, 76, 153–175. 
6. Suffness, M. and Douros, J., J. Nat. 
Prod., 1982, 45, 1–14. 
7. Wall, M. E. and Wani, M. C., J. Ethno-
pharmacol., 1996, 51, 239–254. 
8. Rates, M. K., Toxicon., 2001, 39, 603–
613. 
9. Uma Shaanker, R., Ramesha, B. T., 
Ravikanth, G., Rajesh, P. G., Vasudeva, 
R. and Ganeshiash, K. N., In Bioactive 
Molecules and Medicinal Plants (eds 
Ramawat, K. G. and Merillion, J.), 
Springer-Verlag, Berlin, 2007. 
10. McLaughlin, J. L., In Methods in Plant 
Biochemistry (ed. Hostettmann, K.), Aca-
demic Press, London, 1991, pp. 1–31. 
11. Galsky, A. B., Kozimor, R., Piotrowski, 
D. and Powell, R. G., J. Natl. Cancer 
Inst., 1991, 67, 689–692. 
12. Kahl, G. and Schell, J. S., Molecular Bi-
ology of Tumours, Academic Press, NY, 
1982. 
13. Galsky, A. G., Wilsey, J. P. and Powell, 
R. G., Plant Physiol., 1980, 65, 184–185. 
14. Becker, F. (ed.), In Etiology: Viral Car-
cinogenesis, Plenum Press, NY, 1975, 
pp. 2–544. 
15. Braun, A. C., Prog. Exp. Tumor. Res., 
1972, 15, 165–187. 
16. McLaughlin, J. L. and Rogers, L., Drug 
Inf. J., 1998, 32, 513–524. 
17. Lellau, T. F. and Liebezeit, G., Pharm. 
Biol., 2003, 41, 293–300. 
18. Ahsan, U., Latif, F., Ansari Ihsan-ul-
Haq, Nazir, S. and Mirza, B., Chem. 
Biodivers., 2007, 4, 203–214. 
19. Ferrigni, N. R., Putnam, J. E., Anderson, 
B., Jacobsen, L. B., Nichols, D. E., 
Moore, D. S. and McLaughlin, J. L., J. 
Nat. Prod., 1982, 45, 679–686. 
20. DeCleene, M. and DeLey, J., Bot. Rev., 
1972, 42, 389–466. 
21. Dickersin, K. and Min, Y. I., Ann. N.Y. 
Acad. Sci., 1993, 703, 135–146. 
22. Olson, C. M., Acad. Emerg. Med., 1994, 
1, 207–209. 
23. Smith, E. F., Proc. Natl. Acad. Sci. USA, 
1916, 2, 444–448. 
 
 
 
ACKNOWLEDGEMENTS. Work was par-
tially supported by grants from the Depart-
ment of Biotechnology, New Delhi. Prof. 
N. V. Joshi, Center for Ecological Sciences, 
Indian Institute of Science, Bangalore offered 
critical suggestions on the analysis. Prof. K. 
Veluthambi, Madurai Kamaraj University, 
Madurai drew our attention to the crown gall 
data of DeCleene and DeLey. 
 
 
Received 25 September 2008; accepted 17 
October 2008 
 
R. SRIRAMA1,4 
B. T. RAMESHA1,2 
G. RAVIKANTH1,4 
R. UMA SHAANKER1,2,4,* 
K. N. GANESHAIAH1,3,4 
 
1School of Ecology and Conservation, 
2Department of Crop Physiology, and 
3Department of Forestry and 
 Environmental Sciences, 
University of Agricultural Sciences, 
GKVK, 
Bangalore 560 065, India 
4Conservation Genetics Lab, 
Suri Sehgal Center for 
 Conservation Science, 
Ashoka Trust for Research in 
 Ecology and Environment, Hebbal, 
Bangalore 560 024, India 
*For correspondence. 
e-mail: umashaanker@gmail.com 
 
 
 
Does recent migration explain elevated blood pressure? A study among 
migrants in Delhi, India 
 
Hypertension has emerged as a major 
public health problem in developing 
countries. The association between urba-
nization and blood pressure is well-known. 
However, studies dealing with immediate 
impact of migration are limited in deve-
loping countries1–3. Here, we have tried 
to explore the differences between recent-
migrants and settled-migrants with re-
gard to hypertension. 
 The settled-migrants (who have settled 
and are residing in Delhi since at least 10 
years) were sampled from a resettlement 
colony in South Delhi (Dakshinpuri ex-
tension, Dr Ambedkar Nagar) while the 
recent-migrants (who had migrated to the 
city of Delhi from rural villages within 
the last two years, this being their first 
migration) were selected from slums 
(Prabhu Basti, Indira Camp, Khirki Gaun) 
and work sites (construction work sites at 
Chirag Dilli and South District Office 
complex construction work site at Saket). 
Sample size was estimated according to 
Lwanga and Lemeshow4. With a confi-
dence level of 95% and an absolute pre-
cision of ten percentage points on either 
side of the true value of the difference 
between the proportions, the estimated 
sample size was 193 in each group4. The 
sample size was rounded-off to 200 in 
each group. Five blocks of the resettle-
ment colony were selected randomly for 
the sample of settled-migrants. In each 
block, four streets from four directions 
were selected. In each street, two random 
points were chosen, and from each ran-
dom point five individuals (both men and 
women) were selected randomly in order 
to attain a minimum sample of 200 indi-
viduals. The eligibility criteria for par-
ticipation were that the subject should 
belong to the migrant group and residing 
in Delhi since a minimum of 10 years; 
he/she should be aged 20 years or more. 
The recent-migrants were selected from 
three slums and in addition, due to non-
availability of eligible respondents dur-
ing the daytime, we visited two construc-
tion work sites where they work. This 
approach has been adopted to attain a 
minimum sample of 200 individuals. In 
each slum, community leaders and mem-
bers were contacted to identify the newly 
migrated individuals. The identified in-
dividuals who were aged 20 years and 
above were contacted and after confirm-
ing that they had migrated within two 
years from rural villages and that it was 
their first migration, they were consi-


Are plants with anti-cancer activity resistant to crown gall?: a test of hypothesis

http://precedings.nature.com/documents/1456/version/1

Are plants with anti-cancer activity resistant to crown gall? : A test of hypothesis

Abstract

Similar works

Full text

Available Versions

Nature Precedings

ePrints@ATREE