Grain composition and amino acid content in maize cultivars representing 80 years of commercial maize varieties

In order to determine how modern hybrids have impacted grain composition and amino acid content of the corn crop, we characterized a set of cultivars that were widely grown in different eras from the 1920s through 2001. Grain composition exhibited clear trends with time, with protein decreasing and starch increasing. The effects of different plant densities were examined. The grain protein content of modern hybrids responds to plant density and environment differently than the protein content of older varieties. These differences are consistent with a model in which protein content is modulated by different growth conditions. These differences may explain, in part, the mechanism by which modern hybrids maintain yield in different environments, i.e. reduction of protein content in stressful environments frees resources that are used to maintain yield. We examined the content of the nutritionally limiting essential amino acids lysine, methionine and tryptophan in grain of these cultivars. On a per tissue mass basis, the levels of these amino acids dropped with time while on a per protein basis, their levels were not significantly changed. We conclude that the development of modern hybrids has resulted in maize with reduced protein content, but the nutritional quality of this protein has not changed

Anthocyanins and antioxidant activity in coloured waxy corn at different maturation stages

The anthocyanin content and antioxidant activity of kernels from 12 genotypes of waxy corn at two maturation stages (milk and mature) were investigated. The individual anthocyanins contained in coloured waxy corn were identified and quantified by HPLC-DAD-ESI/MS analysis. Cyanidin-3-glucoside and its derivatives were detected as being most dominant. Furthermore, acylated anthocyanins constituted 67.1–88.2% and 46.2–83.6% of the total contents at the milk and mature stages, respectively. The concentration of monomeric anthocyanin increased throughout the development of each genotype of corn. The antioxidant activity, which was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability, increased with ripening. However, the ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) revealed decreases in some genotypes during ripening. The kernels of a purplish black waxy corn genotype (KKU-WX111031) exhibited the greatest antioxidant activity and contained the highest level of anthocyanins among the genotypes tested at both maturation stages

Anthocyanin, phenolics and antioxidant activity changes in purple waxy corn as affected by traditional cooking

Antioxidant components, including anthocyanins and phenolic compounds, antioxidant activity, and their changes during traditional cooking of fresh purple waxy corn were investigated. As compared to the raw corn, thermal treatment caused significant (p ⩽ 0.05) decreases in each antioxidant compound and antioxidant activity. Steam cooking preserved more antioxidant compounds than boiling. Boiling caused a significant loss of anthocyanin and phenolic compounds into the cooking water. This cooking water is a valuable co-product because it is a good source of purple pigment. By comparing levels of antioxidant compounds in raw and cooked corn, we determined that degradation results in greater loss than leaching or diffusion into cooking water. Additionally, separation of kernels from the cob prior to cooking caused increased loss of antioxidant compounds

Accuracy and Training Population Design for Genomic Selection on Quantitative Traits in Elite North American Oats

Genomic selection (GS) is a method to estimate the breeding values of individuals by using markers throughout the genome. We evaluated the accuracies of GS using data from five traits on 446 oat (Avena sativa L.) lines genotyped with 1005 Diversity Array Technology (DArT) markers and two GS methods (ridge regression–best linear unbiased prediction [RR-BLUP] and BayesCπ) under various training designs. Our objectives were to (i) determine accuracy under increasing marker density and training population size, (ii) assess accuracies when data is divided over time, and (iii) examine accuracy in the presence of population structure. Accuracy increased as the number of markers and training size become larger. Including older lines in the training population increased or maintained accuracy, indicating that older generations retained information useful for predicting validation populations. The presence of population structure affected accuracy: when training and validation subpopulations were closely related accuracy was greater than when they were distantly related, implying that linkage disequilibrium (LD) relationships changed across subpopulations. Across many scenarios involving large training populations, the accuracy of BayesCπ and RR-BLUP did not differ. This empirical study provided evidence regarding the application of GS to hasten the delivery of cultivars through the use of inexpensive and abundant molecular markers available to the public sector

Transgenic maize endosperm containing a milk protein has improved amino acid balance

In order to meet the protein nutrition needs of the world population, greater reliance on plant protein sources will become necessary. The amino acid balance of most plant protein sources does not match the nutritional requirements of monogastric animals, limiting their nutritional value. In cereals, the essential amino acid lysine is deficient. Maize is a major component of human and animal diets worldwide and especially where sources of plant protein are in critical need such as sub-Saharan Africa. To improve the amino acid balance of maize, we developed transgenic maize lines that produce the milk protein α-lactalbumin in the endosperm. Lines in which the transgene was inherited as a single dominant genetic locus were identified. Sibling kernels with or without the transgene were compared to determine the effect of the transgene on kernel traits in lines selected for their high content of α-lactalbumin. Total protein content in endosperm from transgene positive kernels was not significantly different from total protein content in endosperm from transgene negative kernels in three out of four comparisons, whereas the lysine content of the lines examined was 29–47% greater in endosperm from transgene positive kernels. The content of some other amino acids was changed to a lesser extent. Taken together, these changes resulted in the transgenic endosperms having an improved amino acid balance relative to non-transgenic endosperms produced on the same ear. Kernel appearance, weight, density and zein content did not exhibit substantial differences in kernels expressing the transgene when compared to non-expressing siblings. Assessment of the antigenicity and impacts on animal health will be required in order to determine the overall value of this technology

L1 libration point manned space habitat

Second generation stations or Manned Space Habitats (MSHs) are discussed for an Earth-Moon libration point and in lunar orbit. The conceptual design of such a station is outlined. Systems and subsystems described reflect anticipation of moderate technology growth. The evolution of the L1 environments is discussed, several selected subsystems are outlined, and how the L1 MSH will complete some of its activities is described