Recurrent Selection to Alter Grain Methionine Concentration and Improve Nutritional Value of Maize

Abstract

Methionine is an essential amino acid that is limiting in maize-(Zea mays L.) based diets. The objective of this work was to determine whether we could alter grain methionine concentration in random-mated maize populations by mass selection for methionine concentration using a microbial assay. In one study, we developed two populations by selecting for high or low methionine concentration (HM or LM, respectively) for three generations starting from the randommated population BS11. Grain from these populations was used to formulate diets for a feeding trial in which 15 rats were fed HM grain and 15 rats were fed LM grain. Rats on the HM diet had a 0.018 higher feed effi ciency (g gain/g feed) than rats on the LM diet. In a second study, we performed three cycles of selection for high or low methionine concentration starting with two random-mated populations, BS11 and BS31. We evaluated each cycle of selection in a fi eld trial with two replications in each of two years. Methionine concentration was signifi cantly correlated with the cycle of selection, changing on average 0.004 g methionine/100 g grain per cycle. Kernel mass, %N, oil, protein, starch, tryptophan, and lysine concentration did not exhibit signifi cant correlations with cycle of selection. We conclude that recurrent selection for grain methionine concentration using a microbial assay is an effective method to alter methionine content.

Interaction of Genetic Mechanisms Regulating Methionine Concentration in Maize Grain

“…While the effectiveness of dzr1 and recurrent selection were shown by Olsen et al (2003) and Scott et al (2008), respectively, the present study suggests there may be a benefit of having either or both methods in hybrid combination. Current data suggests synergism may exist between dzr1 and recurrent selection because of the significant SCA for methionine concentration in the RS3/B101 hybrid.…”

“…One possible explanation for this observation is that the method used to quantify amino acids is not accurate. It has been shown that there is a high correlation between the AOAC standard method (AOAC International, 1995) for methionine analysis and the bacterial assay used in this study (Scott et al, 2008). In addition, it has been shown that selection for methionine using the microbial growth method results in populations with altered methionine concentration as measured by the AOAC standard high-performance-liquid-chromatograph-based method (Newell et al, 2014).…”

“…The Illinois long-term selection experiment for grain composition (reviewed in Moose et al, 2004) altered protein and oil concentrations to produce populations with trait values representing the known extreme values for maize. Furthermore, Scott et al (2008) altered grain composition by selecting for either high or low methionine concentrations. Three cycles of selection were sufficient to cause a significant difference in methionine concentration between populations selected for high and low values, respectively, illustrating that the methionine concentration of maize grain can be altered by traditional breeding and providing a third approach to increasing methionine concentration.…”

Development of High Protein Populations of Maize (Zea mays L.) From Three Cycles of Reciprocal Recurrent Selection

“…Recurrent selection is one of the most simple ways to improve a trait, if there is a straightforward way to quantify the trait of interest and a population with heritable variation for the trait [7]. Recurrent selection is simply the selection for a certain trait or traits over many generations, and can be used to control complex multigenic traits.…”

The Chronic Ingestion of Diets Containing Different Proteins Produces Marked Variations in Brain Tryptophan Levels and Serotonin Synthesis in the Rat

“…Choi et al recently examined the effects on the serum TRP ratio, brain TRP concentrations and 5HT synthesis of feeding groups of rats meals containing each of several proteins (zein, gluten, casein, soy, lactalbumin) [3]. The amino acid patterns of these proteins, notably their contents of TRP in relation to the other LNAA (i.e., the TRP ratios of the dietary proteins), range widely: lactalbumin, 0.048; soy protein, 0.033, gluten, 0.029, casein, 0.026 and zein, 0.015 [4][5][6]. At moderate levels in the diet, based on recent work by others [7,8], we wondered if the ingestion of these proteins might modify the serum TRP ratio in a direction reflecting their TRP ratios.…”