RESPONSE OF COTTON GENOTYPES TO RELATION TO INDUCTION OF RESISTANCE AGAINST COTTON LEAF CURL DISEASE
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Date
2013
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PAU Ludhiana
Abstract
The present study was conducted to check the response of different American cotton cultivars
namely RS 921, LH 2076, PIL 8, Ankur 3028 BGII and a desi cotton variety LD 694 to
Jasmonic acid (JA) and Salicylic acid (SA) in induction of resistance against cotton leaf curl
disease (CLCuD). Different cotton cultivars were grown in pots under screen cages. At four to
six leaf stage potted plants of different cotton cultivars were treated with different
concentration of JA and SA i.e. 50 μM, 100 μM, 150 μM, 200 μM respectively and water
sprayed plants of corresponding genotypes served as control. Quantification of proteins was
done using spectrophotometric method from the leaf samples collected at 24, 48, 72, 96 hrs and
a week after treatment with JA and SA. Application of JA and SA resulted in the induction of
proteins 24 hrs after treatment. After a week interval at 150 μM concentration of JA maximum
protein induction of 19.9 mg/g fr. wt., 16.7 mg/g fr. wt., 19.6 mg/g fr. wt., 15.0 mg/g fr. wt. and
14.4 mg/g fr. wt. was recorded in RS 921, LH 2076, PIL 8, Ankur 3028 BGII and LD 694
respectively whereas, in case of SA 200 μM concentration showed maximum protein induction
i.e 10.6 mg/g fr. wt., 9.3 mg/g fr. wt., 9.9 mg/g fr. wt., 9.0 mg/g fr. wt., 8.1 mg/g fr. wt. in RS
921, LH 2076, PIL 8, Ankur 3028 BGII and LD 694 respectively. In the induction of proteins
JA was found to be more effective than SA. Electrophoretic study of cotton cultivars treated
with 150 μM of JA and 200 μM of SA revealed the induction of Pathogenesis-related (PR)
proteins ranging from 15-45 kDa along with some other proteins as well. JA and SA applied at
different concentrations affected the CLCuD incidence and severity when inoculated with
viruliferous whiteflies (Bemesia tabaci) in screen cages. Lower disease incidence as well as
disease index was observed with JA when applied @ 150 μM and SA @ 200 μM. Disease
incidence was 37%, 30%, 30% and disease index was 48%, 40%, 40% in RS 921, LH 2076,
Ankur 3028 BGII at 150 μM concentration of JA whereas, at 200 μM SA disease incidence
was 48%, 36%, 34% and disease index was 57%, 50%, 50% respectively in above mentioned
cultivars and in their respective control values for disease incidence and disease severity were
quite high. So, JA at 150 μM and SA at 200 μM concentration was found to be most effective
in lowering the disease. Latent carry over detection of symptomless plants treated with 150 μM
of JA and 200 μM of SA through PCR amplification using DNA specific primers confirmed
the presence of virus in all the tested cotton cultivars except LD 694 which signified that PR
proteins does not eliminate virus. JA and SA application resulted in imparting tolerance with
the induction of PR proteins but does not lead to complete resistance against the disease.
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