Seed phytate content and phosphorus uptake and distribution in dry bean genotypes

Abstract

Phytic acid is the major storage form of phosphorus in seeds of legumes and cereals. Since phytate can form complexes with proteins and minerals, reducing the digestive availability of these nutrients, it is usually regarded as an antinutrient, although recent work indicates that it has important beneficial roles as an antioxidant and anticarcinogen. Therefore, there is an interest in the assessment and manipulation of phytate contents in important food grains such as beans. The objective of this work was to compare eleven dry bean genotypes with regard to grain contents of P, phytate, inorganic P and protein and to examine if differences between genotypes could be explained by differences in grain protein content or in uptake and partitioning of P. Plants were grown in a greenhouse in pots containing soil and commercial substrate amended with 7.4 and 37 mg P.dm-3. The experimental setup was a random, complete block design with five replications. Genetic variability in grain phytate contents was observed. At the higher dose of P fertilization, genotype Una presented the highest phytate content (1.48 %) and the highest fraction of P as phytate (72 %), whereas these features were lowest in Paraiso (0.70 % and 47 %, respectively). Inorganic P made up 8 % of total P in Paraiso. A correlation between phytate and protein contents among genotypes was significant (r = 0.73) only under the higher dose of P fertilization. With the exception of genotype 4AP, differences in phytate content could not be explained by differences in uptake and partitioning of P in the plant. In the case of Paraiso, it is inferred that the lower phytate contents were due to differences in the metabolism of P and dry matter accumulation in the grain.

Variation in phytate accumulation in common bean (Phaseolus vulgaris L.) fruit explants

“…Future studies should be conducted to measure the alteration of the protein synthesis in vitro through the analysis of the accumulation of stored proteins, or the total amino acid content (Mosquim and Sodek, 1991;Mosquim and Sodek, 1992), employing available proteomic and metabolomic techniques (Azevedo et al, 2004a;Azevedo et al, 2004b;Helm et al, 2004), which would allow a more comprehensive evaluation of phytate metabolism. The results obtained with phytate, P and protein accumulation in grain using in vitro the conditions corroborated with the previous studies using in situ conditions and in vitro condition with radiolabeled precursors (Coelho et al, 2002a(Coelho et al, e 2002bCoelho et al, 2005b). In conclusion, P, sucrose, ABA and myo-inositol caused an increase of phytate in common bean seeds (variety Una), thus showing that it could be possible to alter the synthesis of phytate by culturing bean fruit explants in vitro.…”

Comparative evaluation of phosphorus accumulation and partitioning in seeds of common bean (Phaseolus vulgaris L.)

“…Common bean genotypes vary in their efficiency of P uptake from soil, capability to store and partitioning it among different forms (Coelho et al, 2002). Experimental data collected in the present study are in good agreement with literature.…”

Genetic architecture of biofortification traits in soybean (Glycine max L. Merr.) revealed through association analysis and linkage mapping

“…In addition to enhancing mineral concentrations, biofortification also aims to improve the bioavailability of beneficial minerals to reduce global mineral malnutrition. Phytate is the main storage form of seed phosphorus (P) in legumes (Coelho et al 2002). Phytate covalently binds to cations (Ca 2?…”