Functional Plant Biology (2011) 38, 984-992

Ming Pei You, Timothy D. Colmer and Martin J. Barbetti (2011)
Salinity drives host reaction in Phaseolus vulgaris (common bean) to Macrophomina phaseolina
Functional Plant Biology 38 (12), 984-992
Abstract: Productivity of Phaseolus vulgaris L. (common bean) is often limited by diseases such as seedling blight and root and stem rot caused by the fungus Macrophomina phaseolina and by abiotic stresses such as salinity. This paper reports controlled environment studies examining the interaction of biotic (M. phaseolina) and abiotic (NaCl) stresses. Studies were conducted at 32°C. On potato dextrose agar, the growth of two isolates of M. phaseolina (M1, M2) was differentially stimulated by 40 mM NaCl with 1 mM CaSO₄. M. phaseolina was applied as either soil-borne inoculum or directly injected into P. vulgaris hypocotyls. For direct hypocotyl inoculation experiments, there was no difference in disease severity resulting from the two isolates. However, when soil inoculation was undertaken, isolate M2 caused more disease than M1. Addition of 40 mM NaCl to the soil increased disease development and severity (evident 4 days after inoculation), particularly as demonstrated in the hypocotyl inoculation tests, suggesting that salinity stress predisposes plants to infection by this pathogen. Plants infested by M. phaseolina showed increased tissue concentrations of Na⁺ and Cl^- but decreased K⁺ concentration. Hypocotyls generally contained higher Na⁺ concentrations than shoots. Inoculated plants had higher Na⁺ and lower K⁺ concentrations than uninoculated plants. Our studies indicate that M. phaseolina will be a more severe disease threat where P. vulgaris is cultivated in areas affected by soil salinity.
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Link to article at publishers website
Database assignments for author(s): Ming Pei You

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Macrophomina phaseolina	Beans (Phaseolus)