Flavonoids of white lupin roots participate in phosphorus mobilization from soil

Review on iron availability in soil: interaction of Fe minerals, plants, and microbes

“…For instance, for soils where Fe oxides are responsible of phosphate fixation (Borggaard et al 1990;Colombo et al 1994;Hinsinger 2001), low-molecularweight organic acids can favor the availability of phosphate for plants through an exchange process of the anion adsorbed to Fe oxides (Liu et al 1999). An analogous process has been described for flavonoids and citrate released by roots of white lupin, which, solubilizing Fe from an insoluble Fe phosphate, favored indirectly the mobilization and the availability of phosphate (Shaw et al 2006;Tomasi et al 2008). With respect to Fe, it has been demonstrated that the Fe-mobilization capacity of these organic ligands (Cesco et al 2000(Cesco et al , 2010 and the contribution of their Fe complexes in the acquisition process of the micronutrient by plants (Cesco et al 2002(Cesco et al , 2006Pinton et al 1999;Tomasi et al 2009a, b) could be quite different among the complexes.…”

“…Among the organic molecules detected in the rhizosphere in addition to MS s , oxalate needs to be mentioned as for its abundance among rhizodepositions and for its direct involvement in the biological and efficient weathering of minerals (Jones and Wilson 1985;Adamo et al 1997). Flavonoids released by roots have a direct effect on soil minerals and on biological activity in the soil that play an important role in Fe solubilization processes (El Hajji et al 2006;Tomasi et al 2008;Cesco et al 2012). However, although the impact of flavonoids on soil microorganisms could also be of relevance in terms of microbe-mediated Fe oxidation-reduction in soil (Tomasi et al 2008;Cesco et al 2010Cesco et al , 2012, the relative contribution of these molecules to the Fe availability in the rhizosphere and to the use of this Fe source for plant nutrient acquisition has not yet been comprehensively studied.…”

“…Flavonoids released by roots have a direct effect on soil minerals and on biological activity in the soil that play an important role in Fe solubilization processes (El Hajji et al 2006;Tomasi et al 2008;Cesco et al 2012). However, although the impact of flavonoids on soil microorganisms could also be of relevance in terms of microbe-mediated Fe oxidation-reduction in soil (Tomasi et al 2008;Cesco et al 2010Cesco et al , 2012, the relative contribution of these molecules to the Fe availability in the rhizosphere and to the use of this Fe source for plant nutrient acquisition has not yet been comprehensively studied. It appears evident that the release of Fe III -complexing organic compounds by roots and microorganisms can contribute to Fe (hydr)oxides dissolution and/or to Fe mobilization from unavailable sources (see Figs.…”

Plant-borne flavonoids released into the rhizosphere: impact on soil bio-activities related to plant nutrition. A review

“…It has also been shown that flavonoids can stimulate the biodegradation of xenobiotics (Shaw et al 2006) and reduce the degradation of organic acids in the rhizosphere (Tomasi et al 2008). Both concentration and type of flavonoids in the rhizosphere soil are affected by soil microorganisms through modification of root exudation patterns and microbial catabolisms (Shaw et al 2006).…”

Burkholderia Species Are Major Inhabitants of White Lupin Cluster Roots

“…They occur in many species of the Proteaceae family and occasionally in the Mimosaceae, Casuarinaceae, or Fabaceae (7). White lupin is the only cluster-rooted species of agricultural importance and has thus been extensively studied (9,17,26,32,33,41,42). In white lupin, cluster root development follows a well-defined pattern: at the juvenile stage, cluster roots secrete small amounts of malate; at the mature stage, high quantities of citrate and protons are excreted, leading to drastic rhizosphere acidification; and at the senescent stage, organic acid excretion decreases.…”