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ARS Home » Southeast Area » Mayaguez, Puerto Rico » Tropical Crops and Germplasm Research » Research » Publications at this Location » Publication #348979

Research Project: Genetic Enhancement of Common Bean Using Exotic Germplasm for Biotic and Abiotic Stress Tolerance

Location: Tropical Crops and Germplasm Research

Title: Phytic acid transport in Phaseolus vulgaris: a new low phytic acid mutant in the PvMRP1 gene and study of the PvMRPs promoters in two different plant systems

Author
item Cominelli, Eleonora - National Research Council - Italy
item Confalioneri, Massimo - National Research Council - Italy
item Carlessi, Martina - National Research Council - Italy
item Cortinovis, Gaia - National Research Council - Italy
item Daminati, Maria - National Research Council - Italy
item Porch, Timothy - Tim
item Losa, Alessia - National Research Council - Italy
item Sparvoli, Francesca - National Research Council - Italy

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2018
Publication Date: 2/7/2018
Citation: Cominelli, E., Confalioneri, M., Carlessi, M., Cortinovis, G., Daminati, M.G., Porch, T.G., Losa, A., Sparvoli, F. 2018. Phytic acid transport in Phaseolus vulgaris: a new low phytic acid mutant in the PvMRP1 gene and study of the PvMRPs promoters in two different plant systems. Theoretical and Applied Genetics. https://doi: 10.1016/j.plantsci.2018.02.003.
DOI: https://doi.org/10.1016/j.plantsci.2018.02.003

Interpretive Summary: Phytic acid is the main storage form of phosphate in seeds and in the plant it plays an important role in signal transduction in response to environmental stress and hormonal changes. Phytic acid is a strong chelator of mono and divalent cations, such as iron, zinc, magnesium and calcium, reducing the bioavailability of these essential minerals in the diet, thus making these minerals less available for human nutrition. A single common bean low phytic acid (lpa1) mutant, affected in the PvMRP1 gene, has been described so far. This mutant is devoid of other associated negative effects normally characterising lpa mutants. With the aim of isolating new common bean lpa mutants, an ethyl methane sulfonate (EMS) mutagenized population was screened resulting in the identification of an additional lpa1 allele. Other putative lpa mutants were also isolated. The new mutation was identified in the PvMRP2 gene, a paralog of PvMRP1, that is probably able to complement the phenotype of mutants affected in the PvMRP1 gene in tissues other than the seed, thus explaining the lack of other negative side effects in the two bean mutants. Expression analysis revealed that only PvMRP1 is expressed at appreciable levels in cotyledons. Moreover, 1.5 kb portions of the sequences of both genes were generated and used to transform Arabidopsis thaliana and Medicago truncatula. An indicator for gene activity, GUS, suggests a refined, species-specific mechanism of regulation of gene expression for these two PvMRP genes.

Technical Abstract: Phytic acid (InsP6) is the main storage form of phosphate in seeds and in the plant it plays an important role in signal transduction in response to environmental stress and hormonal changes. InsP6 is a strong chelator of mono and divalent cations, such as iron, zinc, magnesium and calcium, reducing the bioavailability of these essential minerals in the diet. Only a common bean low phytic acid (lpa1) mutant, affected in the PvMRP1 gene, coding for a putative tonoplastic phytic acid transporter, was described so far. This mutant is devoid of negative pleiotropic effects normally characterising lpa mutants. With the aim of isolating new common bean lpa mutants, an ethyl methane sulfonate (EMS) mutagenized population was screened resulting in the identification of an additional lpa1 allele. Other putative lpa lines were also isolated. The PvMRP2 gene, a paralog of PvMRP1, is probably able to complement the phenotype of mutants affected in the PvMRP1 gene in tissues other than the seed, thus explaining the lack of pleiotropic effects in the two bean mutants. Expression analysis revealed that only PvMRP1 is expressed at appreciable levels in cotyledons. Moreover, constructs harbouring 1.5 kb portions of the intergenic 5’ sequences of both genes, fused upstream of the GUS reporter, were generated and used to transform Arabidopsis thaliana and Medicago truncatula. GUS activity obtained in different organs suggest a refined, species-specific mechanisms of regulation of gene expression for these two PvMRP genes.