Exotic Corn Lines with Increased Resistant Starch and Impact on Starch Thermal Characteristics

Abstract

Ten parent corn lines, including four mutants (dull sugary2, amyloseextender sugary2, amylose-extender dull, and an amylose-extender with introgressed Guatemalen germplasm [GUAT ae]) and six lines with introgressed exotic germplasm backgrounds, were crossed with each other to create 20 progeny crosses to increase resistant starch (RS) as a dietary fiber in corn starch and to provide materials for thermal evaluation. The resistant starch 2 (RS2) values from the 10 parent lines were 18.3-52.2% and the values from the 20 progeny crosses were 16.6-34.0%. The %RS2 of parents was not additive in the offspring but greater RS2 in parents was correlated to greater RS2 in the progeny crosses (r = 0.63). Differential scanning calorimetry (DSC) measured starch thermal characteristics, revealing positive correlations of peak gelatinization temperature and change in enthalpy with %RS2 (r = 0.65 and r = 0.67, P ≤ 0.05); however, % retrogradation (a measure of RS3) and retrogradation parameters did not correlate with %RS2. The %RS2 and onset temperature increased with the addition of the ae gene, likely because RS delays gelatinization. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Ten parent corn lines, including four mutants (dull sugary2, amyloseextender sugary2, amylose-extender dull, and an amylose-extender with introgressed Guatemalen germplasm [GUAT ae]) and six lines with introgressed exotic germplasm backgrounds, were crossed with each other to create 20 progeny crosses to increase resistant starch (RS) as a dietary fiber in corn starch and to provide materials for thermal evaluation. The resistant starch 2 (RS2) values from the 10 parent lines were 18.3-52.2% and the values from the 20 progeny crosses were 16.6-34.0%. The %RS2 ABSTRACT

Resistant Starch and Starch Thermal Characteristics in Exotic Corn Lines Grown in Temperate and Tropical Environments

“…RS measured by the Megazyme RS kit is RS2 because the starch used in the analysis is not gelatinized, so our positive correlation between RS and T o g would have a similar explanation. Rohlfing et al (2010) found a correlation between their measurement of RS2 and H g but were unable to …”

“…Rohlfing et al (2010) found correlation between peak temperature of gelatinization (T p g ) and RS, attributing the correlation to the presence of RS2 that would delay gelatinization. RS measured by the Megazyme RS kit is RS2 because the starch used in the analysis is not gelatinized, so our positive correlation between RS and T o g would have a similar explanation.…”

“…Whereas our previous study included genotypes that were developed and selected for RS, and subsequently many had higher values for this characteristic (Rohlfing et al 2010), in this study we examined a set of nonmutant lines selected for high yield. Although partly of exotic origin and thus possibly having modifying genes affecting RS, the lines were not expected to have unusual levels of RS and did not (Supplementary Table I).…”

“…The U.S. successor to LAMP, Germplasm Enhancement of Maize (GEM) (Pollak 2003;Salhuana and Pollak 2006), enhances useful exotic germplasm to diversify the U.S. hybrid corn germplasm base. This germplasm also provides opportunity to impact starch traits (Singh et al 2001a(Singh et al , 2001b(Singh et al , 2001cCampbell et al 2002;Ji et al 2004;Lenihan et al 2005;Taboada-Gaytan et al 2009, 2010a, 2010bRohlfing et al 2010).…”

Evaluation of grain nutritional quality and resistant starch content in Kenyan bread wheat varieties

“…However, for RS, environmental variation component is difficult to predict and control compared to genetic variation (Birt et al, 2013). Genetic variation occurs within botanical sources due to allelic variation in the starch biosynthetic genes as is the case in commercial maize varieties, which exhibit little variation in resistant starch levels (Rohlfing et al, 2010;Pollack et al, 2011). This variation in RS content was observed in our study genotypes with some recording upto 5 folds more RS than others when grown in the same site (Table 4).…”