Actinomycetes and their secondary metabolites to control multiple pathogens of chickpea Actinomycetes and their secondary metabolites to control multiple pathogens of chickpea and sorghumand sorghum
S. Gopalakrishnan* and GV Ranga RaoS. Gopalakrishnan* and GV Ranga Rao
ICRISAT, Patancheru, Hyderabad, Andhra Pradesh, IndiaICRISAT, Patancheru, Hyderabad, Andhra Pradesh, India
*Corresponding author: [email protected]
SRICONT
INTRODUCTIONINTRODUCTION In the present study, 25 different herbal In the present study, 25 different herbal vermicomposts were screened for actinomycetes that contain antifungal vermicomposts were screened for actinomycetes that contain antifungal potential against potential against FusariumFusarium wilt and collar rot of chickpea (caused by wilt and collar rot of chickpea (caused by Fusarium oxysporumFusarium oxysporum f. sp. f. sp. cicericiceri and and Sclerotium rolfsiiSclerotium rolfsii, respectively) and , respectively) and charcoal rot of sorghum (caused by charcoal rot of sorghum (caused by Macrophomina phaseolinaMacrophomina phaseolina) and anti-) and anti-insect potential against insect potential against Helicoverpa armigeraHelicoverpa armigera, the polyphagous pest of , the polyphagous pest of many crops. The promising ones were selected further for metabolite many crops. The promising ones were selected further for metabolite purification studies.purification studies.
MATERIALS AND METHODSMATERIALS AND METHODSProminent actinomycetes isolated with SCA by spread plate methods.In-vitro antifungal activity by dual-culture assay.In-vivo anti-insect activity by bioassay (on 3rd instar Helicoverpa larvae)Evaluated for PGP traits on respective selective media.Actinomycetes identified by 16S rDNA analysis. Metabolite production capability by solvent partitioning and bioassay.Partial purification done by SPE and open column chromatography.
RESULTSRESULTS Three most promising actinomycetes (CAI-21, CAI-26 and MMA-32)
based on biocontrol and PGP traits were further studied CAI-21 was identified as Streptomyces albus, while CAI-26 and MMA-32
were identified as S. champavatii and S. roseoviolaeus, respectively. Culture filtrates of all the three actinomycetes completely inhibited FOC
but not M. phaseolina completely. However, all the culture filtrates inhibited another pathogen of chickpea, Sclerotium rolfsii which causes collar rot.
Culture filtrates of all the actinomycetes showed 58-78% mortality over control.
Upon further fractionation of the culture filtrates of one of the actinomycetes (CAI-21) by open column chromatography, only 80% MeOH fraction showed inhibition of FOC.
Molecular identification of the potential actinomycetes
Control CA1-17
The list of herbal vermicomposts used in this studyJatropha curcas, Annona squamosa, Parthenium hysterophorus, Oryza sativa, Gliricidia sepium, Adhatoda vasica, Azadirachta indica, Capsicum annuum, Calotropis gigantea, Calotropis procera, Datura metal, Allium sativum, Zingiber officinale, Ipomoea batatas, Momordica charantia, Moringa oleifera, Argyranthemum frutescens, Nerium indicum, Allium cepa, Curcuma aromatica, Pongamia pinnata, Abacopteris multilineata, Nicotiana tabacum, Tridax procumbens and Vitex negundo The effect of culture filtrates of actinomycetes on FOC
The effect of culture filtrates of actinomycetes on S. rolfsii
0
20
40
60
80
100
CAI-21 CAI-26 MMA-32 Control
Actinomycetes
% M
orta
lity
The effect of culture filtrates of actinomycetes on H. armigera
0
0.01
0.02
0.03
0.04
0.05
0.06
CAI-21 CAI-26 MMA-32 Control
Actinomycetes
Dry
wt (g
)
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
CAI-21 CAI-26 MMA-32 Control
Actinomycetes
Dry
wt (g
)
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Con Crude Crude 4T NAF 10% 20% 40% 60% 80% 80% 4T 100%
Open column fractions in MeOH (adsorbed)
Dry
wei
ght (g
m)
Fractionation of culture filtrates of CAI-21 on an open column chromatography: on FOC
Strains Matched with NBAIM ACC No
CAI-21 Streptomyces albusNAIMCC-B-01089
CAI-26Streptomyces champavatii
NAIMCC-B-01090
MMA-32Streptomyces roseoviolaeus
NAIMCC-B-01091
Biocontrol and PGP traits of the actinomycetes
On FOC On M. phaseolinaOn S. rolfsii
The effect of culture filtrate of CAI-21 on various pathogens
