Enhanced Mn accumulation by snapbean cultivars under FE stress

Publisher Website
Google Scholar
Abstract
Iron deficiency in dicots is accompanied by an increased potential for Fe uptake and translocation. The mechanisms responsible for these changes in metabolism (Fe‐stress response) provide for the adaptation of Fe‐efficient genotypes to conditions which limit the availability of Fe. Previous studies indicated that when Fe‐stress response is initiated, the uptake of Mn, as well as Fe, is enhanced in Fe efficient species such as sunflower. The present study was conducted to determine the relationship between Fe‐stress response and Mn uptake in snapbean (Phaseolus vulgaris L., cvs. Bush Blue Lake 290, Bush Blue Lake 274). The plants were grown in complete nutrient solutions containing 0.02 to 0.52 mg L‐1 Mn, at acid or alkaline pH. Iron stress was induced with 0.22 mg l‐1 Fe(EDDHA) (molar ratio 1:1 or 1:2), high P (14.3 mg L‐1) and excess CaCO3. Bush Blue Lake 290 ('BBL 290') was more sensitive than Bush Blue Lake 274 ('BBL 274') to Mn toxicity in acid (pH 5.2) nutrient solutions with adequate Fe. Under alkaline conditions, Mn accumulation by ‘BBL 290’ snapbean was increased dramatically with Fe stress, while a moderate Increase was found for ‘BBL 274’. Foliar symptoms of Mn toxicity, observed on Fe stressed ‘BBL 290’, increased in severity at higher Mn (0.06 to 0.26 mg L‐1 ) concentrations. It was concluded that the magnitude of the enhanced Mn uptake was related to the intensity of Fe stress response as well as the cultivar sensitivity to Mn.