Dry beans (Phaseolus vulgaris L.) contain high levels of folates, yet the level of folate may vary among different genotypes. Folates are essential vitamins and folate deficiencies may lead to a number of health problems. Among the different forms of folates, 5-methyltetrahydrofolate (5MTHF) comprises more than 80% of the total folate in dry beans. The objectives of this paper were to compare selected genotypes of dry beans for the folate content of the dry seeds and to identify quantitative trait loci (QTL) associated with the folate content in a population derived from an inter-gene-pool cross of dry beans. The folate content was examined in three large-seeded (AC Elk, Redhawk, and Taylor) and one medium-seeded (Othello) dry bean genotypes, their six F1 (i.e., one-way diallel crosses), and the F2 of Othello/Redhawk that were evaluated in the field in 2009. Total folate and 5MTHF contents were measured twice with one-hour time interval. The significant variation ( ) in the folate content was observed among the parental genotypes, their F1 progeny, and members of the F2 population, ranging from 147 to 345？μg/100？g. There was a reduction in the 5MTHF and total folate contents in the second compared to the first measurement. Dark red kidney variety Redhawk consistently had the highest and pinto Othello had the lowest total folate and 5MTHF contents in both measurements. A single marker QTL analysis identified three QTL for total folate and 5MTHF contents in the first measurement and one marker for the total folate in the second measurement in the F2. These QTL had significant dominance effects and individually accounted for 7.7% to 10.5% of the total phenotypic variance. The total phenotypic variance explained by the four QTL was 18% for 5MTHF and 19% for total folate in the first measurement, but only 8% for total folate in the second measurement. 1. Introduction Dry beans (Phaseolus vulgaris L.), in addition to being excellent sources of protein and dietary fibre [1], are also good sources of minerals such as iron, calcium, and zinc, as well as folate [2]. Folate is the general term used to refer to different chemical forms of vitamin B9 [3]. Naturally occurring forms of folate include tetrahydrofolate, 5-methyl tetrahydrofolate (5MTHF), 5-formyltetrahydrofolate, and 10-formyltetrahydrofolate [3]. Among the naturally occurring forms, 5MTHF is the most dominant and readily available form found in plant and animal metabolic cycles [4]. Previous research has indicated that 5MTHF comprises more than 85% of total folate in some major vegetables and close to
References
[1]
M. Duranti, “Grain legume proteins and nutraceutical properties,” Fitoterapia, vol. 77, no. 2, pp. 67–82, 2006.
[2]
M. Hefni, V. ？hrvik, M. Tabekha, and C. Witth？ft, “Folate content in foods commonly consumed in Egypt,” Food Chemistry, vol. 121, no. 2, pp. 540–545, 2010.
[3]
J. Arcot and A. Shrestha, “Folate: methods of analysis,” Trends in Food Science and Technology, vol. 16, no. 6-7, pp. 253–266, 2005.
[4]
T. Brody, J. E. Watson, and E. L. R. Stokstad, “Folate pentaglumate and folate hexaglumate mediated one carbon metabolism,” Biochemestry, vol. 21, pp. 276–282, 1982.
[5]
L. Vahteristo, K. Lehikoinen, V. Ollilainen, and P. Varo, “Application of an HPLC assay for the determination of folate derivatives in some vegetables, fruits and berries consumed in Finland,” Food Chemistry, vol. 59, no. 4, pp. 589–597, 1997.
[6]
A. H. Steindal, A. Juzeniene, A. Johnsson, and J. Moan, “Photodegradation of 5-methyltetrahydrofolate: biophysical Aspects,” Photochemistry and Photobiology, vol. 82, no. 6, pp. 1651–1655, 2006.
[7]
S. Roje, “Vitamin B biosynthesis in plants,” Phytochemistry, vol. 68, no. 14, pp. 1904–1921, 2007.
[8]
J. Geisel, “Folic acid and neural tube defects in pregnancy: a review,” Journal of Perinatal Neonatal Nutritions, vol. 17, pp. 268–279, 2003.
[9]
F. M. A. Islam, K. E. Basford, C. Jara, R. J. Redden, and S. Beebe, “Seed compositional and disease resistance differences among gene pools in cultivated common bean,” Genetic Resources and Crop Evolution, vol. 49, no. 3, pp. 285–293, 2002.
[10]
S. Xue, X. Ye, J. Shi et al., “Degradation kinetics of folate (5-methyltetrahydrofolate) in navy beans under various processing conditions,” Food Science and Technology, vol. 44, no. 1, pp. 231–238, 2011.
[11]
SAS Institute, SAS User's Guide, SAS Institute, Cary, NC, USA, 2010.
[12]
R. A. Scott and G. A. Milliken, “A SAS program for analyzing augmented randomized complete-block designs,” Crop Science, vol. 33, no. 4, pp. 865–867, 1993.
[13]
C. Shi, A. Navabi, and K. Yu, “Association mapping of common bacterial blight resistance QTL in Ontario bean breeding populations,” BMC Plant Biology, vol. 11, no. 1, article no. 52, 2011.
[14]
J. W. Van Ooijen, “JoinMap 4, Software for the calculation of genetic linkage maps in experimental populations,” Kyazma B.V., Wageningen, The Netherlands, 2006.
[15]
M. McConnell, S. Mamidi, R. Lee et al., “Syntenic relationships among legumes revealed using a gene-based genetic linkage map of common bean (Phaseolus vulgaris L.),” Theoretical and Applied Genetics, vol. 121, no. 6, pp. 1103–1116, 2010.
[16]
M. W. Blair, C. Astudillo, M. A. Grusak, R. Graham, and S. E. Beebe, “Inheritance of seed iron and zinc concentrations in common bean (Phaseolus vulgaris L.),” Molecular Breeding, vol. 23, no. 2, pp. 197–207, 2009.
[17]
K. A. Cichy, S. Forster, K. F. Grafton, and G. L. Hosfield, “Inheritance of seed zinc accumulation in navy bean,” Crop Science, vol. 45, no. 3, pp. 864–870, 2005.
[18]
J. Dang, J. Arcot, and A. Shrestha, “Folate retention in selected processed legumes,” Food Chemistry, vol. 68, no. 3, pp. 295–298, 2000.
[19]
M. Johansson, C. Furuhagen, W. Fr？lich, and M. J？gerstad, “Folate content in frozen vegetarian ready meals and folate retention after different reheating methods,” Food Science and Technology, vol. 41, no. 3, pp. 528–536, 2008.
[20]
M. L. Jones and P. F. Nixon, “Tetrahydrofolates are greatly stabilized by binding to bovine milk folate-binding protein,” Journal of Nutrition, vol. 132, no. 9, pp. 2690–2694, 2002.
[21]
G. Orsomando, R. D. De La Garza, B. J. Green et al., “Plant γ-glutamyl hydrolases and folate polyglutamates: characterization, compartmentation, and co-occurrence in vacuoles,” Journal of Biological Chemistry, vol. 280, no. 32, pp. 28877–28884, 2005.
[22]
Y. Wang, Z. Nimec, T. J. Ryan, J. A. Dias, and J. Galivan, “The properties of the secreted γ-glutamyl hydrolases from H35 hepatoma cells,” Biochimica et Biophysica Acta, vol. 1164, no. 3, pp. 227–235, 1993.
