Metabolite Analyses of Grain from Maize Hybrids Grown in the United States under Drought and Watered Conditions during the 2002 Field Season

Abstract

Understanding natural variation in the composition of conventional crop germplasms is critical in establishing a baseline for comparison of biotechnology-derived crops. This is particularly relevant to such traits as tolerance to drought stress. Thus, there is both a need to understand the contribution of stress conditions to natural variation in plant nutritional components and to determine whether levels of small molecule metabolites such as osmoprotectants and stress metabolites are also affected. As a first step in developing such information for maize, seven conventional hybrids were grown under different moisture regimens and the impact of moisture on composition was assessed. The regimens included well-watered conditions, water restriction during the vegetative phase, and water restriction during grain fill. Compositional analyses of the harvested grain included assessments of the levels of proximates (moisture, protein, oil, starch) and small molecule metabolites such as fatty acids, free amino acids, organic acids, sugars, total glycerol, glycine betaine, and abscisic acid. Ranges for these analytes were determined across all moisture regimens, and the effect of the different water regimens on these analytes was also evaluated. The number and type of grain analytes that showed statistically significant differences in levels between different water regimens differed quite markedly by maize hybrid. However, the magnitude of mean differences between well-watered and water-restricted samples was typically small, and statistically significant differences for any given analyte were typically observed in only one to three of the seven maize hybrids. Only two analytes, free glutamine and free proline, showed a significant drought-induced difference in at least four maize hybrids.

The Influence of Fruit Load on the Tomato Pericarp Metabolome in aSolanum chmielewskiiIntrogression Line Population

“…This clearly suggests that a cultivation practice managing carbon availability has a massive effect on metabolite content and as such is most likely to influence crop product quality . However, the relative paucity of similar analyses (including only Arabidopsis ecotypes , tomato [Schauer et al, , 2008, and smaller scale studies in maize [Harrigan et al, 2007] and rice [Kusano et al, 2007]) makes it, as yet, difficult to generalize. Therefore, we decided to concentrate on the most striking features of the data set that we present here: the dramatic increase in amino acid levels following fruit thinning.…”

“…Moreover, the vast majority of metabolomics studies to date have focused on the primary or secondary metabolism of Arabidopsis (Arabidopsis thaliana; Keurentjes et al, 2006;Lisec et al, 2006Lisec et al, , 2008Rowe et al, 2008). That said, several recent studies have evaluated natural variance in the metabolomes of rice (Oryza sativa; Kusano et al, 2007), maize (Harrigan et al, 2007), Brassica napus (Magrath et al, 1993), and even sesame (Sesamum indicum; Laurentin et al, 2008), whereas considerable research effort has been expended on determining QTLs for primary metabolites, acyl sugars, carotenoids, and volatile organic components of tomato (Solanum lycopersicum) fruits (Causse et al, 2004;Fraser and Bramley, 2004;Schauer et al, , 2008Tieman et al, 2006b;Stevens et al, 2007;Dal Cin et al, 2009;Mathieu et al, 2009;Schilmiller et al, 2010).…”

Mode of Inheritance of Primary Metabolic Traits in Tomato

“…Such studies have included detailed dissection of the pathways of glucosinolate biosynthesis (Heidel et al, 2006), seed oil synthesis (Hobbs et al, 2004), and seed-soluble oligosaccharide metabolism (Bentsink et al, 2000) in Arabidopsis as well as flavonoid biosynthesis in Populus (Morreel et al, 2006). Furthermore, within the last year, several studies have been performed at the metabolomic level in Arabidopsis, tomato, and wheat (Triticum aestivum) (Keurentjes et al, 2006;Harrigan et al, 2007b;Meyer et al, 2007).…”

“…Indeed, very few studies concerned with broad metabolite profiling of natural variance have considered this factor to date. One exception is the recent study of Harrigan et al (2007b), who evaluated the levels of a wide range of compositional traits, including protein and oil content as well as fatty acid, amino acid, and organic acid content, in two independent maize hybrids grown at three separate locations.…”

Genetics, Genomics and Metabolomics

“…The metabolome however is much more flexible in terms of chemical structure and function (Sumner et al, 2003;D'Auria & Gershenzon, 2005). This diversity in metabolites, as intermediates and end-products of biochemical pathways, is controlled by a combination of many structural and regulatory genes in addition to environmental influences (Harrigan et al, 2007b). As primary producers of the food chain, plants can generally not rely on intake of substances from other organisms and therefore depend on synthesis of complex compounds from basic components such as carbon dioxide and nutrient elements taken up from their surroundings.…”