Enhancement of downy mildew disease resistance in pearl millet by the G_app7 bioactive compound produced by Ganoderma applanatum.
Pearl millet (Pennisetum glaucum) stands sixth among the most important cereal crops grown in the semi-arid and arid regions of the world. The downy mildew disease caused by Sclerospora graminicola, an oomycete pathogen, has been recognized as a major biotic constraint in pearl millet production. On the other hand, basidiomycetes are known to produce a large number of antimicrobial metabolites, providing a good source of anti-oomycete agrochemicals. Here, we report the discovery and efficacy of a compound, named G_app7, purified from Ganoderma applanatum on inhibition of growth and development of S. graminicola, as well as the effects of seed treatment with G_app7 on protection of pearl millet from downy mildew. G_app7 consistently demonstrated remarkable effects against S. graminicola by recording significant inhibition of sporangium formation (41.4%), zoospore release (77.5%) and zoospore motility (91%). Analyses of G_app7 compound using two-dimensional nuclear magnetic resonance spectroscopy and liquid chromatography-mass spectrometry revealed its close resemblance to metominostrobin, a derivative of strobilurin group of fungicides. Furthermore, the G_app7 was shown to stably maintain the inhibitory effects at different temperatures between 25 and 80 °C. In addition, the anti-oomycete activity of G_app7 was fairly stable for a period of at least 12 months at 4 °C and was only completely lost after being autoclaved. Seed treatment with G_app7 resulted in a significant increase in disease protection (63%) under greenhouse conditions compared with water control. The identification and isolation of this novel and functional anti-oomycete compound from G. applanatum provide a considerable agrochemical importance for plant protection against downy mildew in an environmentally safe and economical manner.
Plant Healthcare and Diagnostic Center, Department of Studies in Biotechnology and Microbiology, Karnatak University, Dharwad 580 003, India. Electronic address: jsudish@kud.ac.in.
Sudisha
S
Jogaiah
Downy Mildew Research Laboratory, Department of Biotechnology, University of Mysore, Manasagangotri, Mysore 570006, Karnataka, India.
Hunthrike Shekar
HS
Shetty
Laboratory of Molecular Plant Pathology, Department of Biological and Environmental Sciences, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan.
Shin-Ichi
SI
Ito
Plant Abiotic Stress Research Group & Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Viet Nam; Signaling Pathway Research Unit, RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, 230-0045 Yokohama, Japan. Electronic address: sontran@tdt.edu.vn.
Lam-Son Phan
LP
Tran
D001688:Biological Products / Q000302:isolation & purification / Q000494:pharmacology*; D066241:Carbon-13 Magnetic Resonance Spectroscopy; D002853:Chromatography, Liquid; D002855:Chromatography, Thin Layer; D060467:Disease Resistance / Q000187:drug effects; D032902:Ganoderma / Q000378:metabolism*; D013058:Mass Spectrometry; D031782:Pennisetum / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology*; D044742:Peronospora / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology*; D018515:Plant Leaves / Q000187:drug effects / Q000382:microbiology; D066244:Proton Magnetic Resonance Spectroscopy; D013170:Spores / Q000187:drug effects; D013696:Temperature
D001688:Biological Products
2D NMR; Anti-oomycete compound; Downy mildew disease resistance; Ganoderma applanatum; LC-MS; Pearl millet; Sclerospora graminicola