Evaluation of host-plant resistance in chickpea by microbial treatment.
1. Objective of activity and intended output:
The objective is to evaluate host plant resistance in chickpea by 3 endophytic
actinomycetes against Botrytis cinerea under controlled environmental conditions through
antioxidant analysis and histochemical studies. Role of microbes in enhancing host-plant
resistance will be identified.
2. Materials and methods:
Three chickpea endophytes AUR-2, AUR-4 and ARR-10 were found effective against
B. cinerea in vitro conditions in the previous screening. Under controlled conditions (1500 Lux
light intensity, 12 h/day; 100% RH, 15±2 °C Temperature), these isolates were tested for its
efficacy on 3 Desi chickpea genotypes including susceptible (ICC4954), moderately resistant
(ICCV05530) and nationally adapted cultivar (JG11) as individual and consortium.
Commercially available Trichoderma (ECOSOM®-TH) is used as standard biological
treatment. The 12 day study has designed to evaluate the disease incidence, anti-oxidant system
and lignin deposition (Anuradha et al. 2011, Singh et al. 2013).
3. Results and interpretation:
Three chickpea endophytic actinobacteria found to be effective against B. cinerea were
identified as Streptomyces sp. From the data of severity index, JG-11 was observed to be
moderately resistant to B. cinerea and on par with ICCV05530, the moderately resistant
cultivar. The TPC was found to be increased on endophyte treated groups (5-8 fold) than the
normal control and disease control groups irrespective of the chickpea genotypes (Fig. 1). The
elevated MDA values (16-21 fold) on disease control groups and reduced MDA levels on
endophyte treatment (9-15 fold) is an indication for the lesser disease severity by microbial
treatment (Fig. 1). The evaluated antioxidant enzymes such as superoxide dismutase (SOD),
catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione peroxidase
(GPX), glutathione reductase (GR), phenyl alanine ammonia lyase (PAL) and poly phenol
oxidase (PPO) reveals the role of microbes in enhancing antioxidant system and hence hostplant resistance. Histochemical staining of chickpea stem sections documented variations in
lignin deposition over the endophyte treatment (Fig. 2). Maximum and uniform lignin
deposition in vascular bundles was found in the endophyte consortium and Trichoderma treated
groups. In addition, B. cinerea challenged groups showed lesser lignification.
4. Next steps:
Evaluation on the effect of microbial treatment on phenolic profiling of chickpea.
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Fig. 1 Changes in TPC and MDA content in chickpea plantlets after treatments with B.
cinerea and endophytes AUR-2, AUR-4 and ARR-10
Each bar depicts the mean of triplicate analysis. Error bar indicates the standard error. Different
letters indicate significant differences among treatments according to Tukey’s test (p≤0.05).
T1:Control (without B. cinerea and endophytes); T2:Control+B. cinerea; T3:T2+AUR-2;
T4:T2+AUR-4; T5:T2+ARR-10; T6:T2+AUR-2+AUR-4+ARR-10; T7:T2+Trichoderma;
G1:JG-11; G2:ICCV05530; G3:ICC4954.
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Fig.2 Effect of endophyte treatment on lignification of chickpea (JG11) stem
NC – Normal Control (B. cinerea unchallenged); DC – Disease Control (B. cinerea
challenged); EC – Endophyte Consortium (B. cinerea challenged and treated with endophytic
consortium); a – Cross section of chickpea stem (10X); b – Phloem of chickpea stem cross
section (40X); c – Xylem of chickpea stem cross section (40X).
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