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Physiology and Biochemistry

The Effect of Iron and Boron Amendments on Infection of Bean by Fusarium solani. Daniel Guerra, Former research associate, Department of Biology, Utah State University, Logan 84322, Present address: USDA-ARS, Northern Regional Center, 1815 N. University, Peoria, IL 61604; Anne J. Anderson, associate professor, Department of Biology, Utah State University, Logan 84322. Phytopathology 75:989-991. Accepted for publication 1 April 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-989.

Mineral nutrition may affect the interaction of plants with microorganisms because of perturbations in phenol metabolism. On bean (Phaseolus vulgaris), Fusarium solani f. sp. phaseoli produces hypocotyl lesions in which phenolic components accumulate. Lesion size was increased 59- 91% by growing bean seedlings in hydroponic solutions containing lower (5 μM FeCl3) rather than higher (50 μM FeCl3) iron content. Absence of boron in the nutrient solutions caused a 47- 75% increase in lesion size compared to those in seedlings grown with 25 μM borate. In nutrient solutions lacking boron but containing 5 μM FeCl3, the lesion size was 183% larger than for plants grown with 50 μM FeCl3 and 25 μM borate. Although iron and boron deficiencies both contributed to increased lesion size, low availability of these nutrients differentially affected the accumulation of lignin. Absence of boron increased the accumulation of polymerized phenolics in the lesion area by about 10%; whereas, low iron availability reduced lignin formation by about 30%.