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Intracellular distribution and binding state of aluminum in root apices of two common bean ( Phaseolus vulgaris ) genotypes in relation to Al toxicity
Author(s) -
Rangel Andrés Felipe,
Rao Idupulapati Madhusudana,
Horst Walter Johannes
Publication year - 2009
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2008.01183.x
Subject(s) - apoplast , phaseolus , elongation , pectin , cell wall , apex (geometry) , biology , horticulture , intracellular , botany , biophysics , biochemistry , materials science , metallurgy , ultimate tensile strength
The role of the intracellular distribution and binding state of aluminum (Al) in Al toxicity, using Al exchange and Al fractionation methodologies, were studied in two common bean ( Phaseolus vulgaris L.) genotypes differing in Al resistance. These two genotypes are characterized by a similar initial period (4 h) of Al sensitivity followed by a contrasting recovery period (8–24 h). A higher initial Al accumulation in Quimbaya (Al resistant) in the 5‐mm root apex compared with VAX‐1 (Al sensitive) could be related to its higher content of unmethylated pectin and thus higher negative charge of the cell walls (CWs). The binding state and cellular distribution of Al in the root apices revealed that the root elongation rate was significantly negatively correlated with the free apoplastic and the stable‐bound, not citrate‐exchangeable CW Al representing the most important Al fraction in the root apex (80%), but not with the symplastic and the labile‐bound, citrate‐exchangeable CW Al. It is postulated that the induced and sustained recovery from the initial Al stress in the Al‐resistant genotype Quimbaya requires reducing the stable‐bound Al in the apoplast thus allowing cell elongation and division to resume.