University of Guelph

About: University of Guelph is a education organization based out in Guelph, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 26542 authors who have published 50553 publications receiving 1715255 citations. The organization is also known as: U of G & Guelph University.

Singular-Value Partitioning in Biplot Analysis of Multienvironment Trial Data

Abstract: Multienvironment trials (MET) are conducted every year for all major crops throughout the world, and best use of the information contained in MET data for cultivar evaluation and recommendation has been an important issue in plant breeding and agricultural research. A genotype main effect plus genotype × environment interaction (GGE) biplot based on MET data allows visualizing (i) the which-won-where pattern of the MET, (ii) the interrelationship among test environments, and (iii) the ranking of genotypes based on both mean performance and stability. Correct visualization of these aspects, however, requires appropriate singular-value (SV) partitioning between the genotype and environment eigenvectors. This paper compares four SV scaling methods. Genotype-focused scaling partitions the entire SV to the genotype eigenvectors; environment-focused scaling partitions the entire SV to the environment eigenvectors; symmetrical scaling splits the SV symmetrically between the genotype and the environment eigenvectors; and equal-space scaling splits the SV such that genotype markers and environment markers take equal biplot space. It is recommended that the genotype-focused scaling be used in visualizing the interrelationship and comparison among genotypes and the environment-focused scaling be used in visualizing the interrelationship and comparison among environments. All scaling methods are equally valid in visualizing the which-won-where pattern of the MET data, but the symmetric scaling is preferred because it has all properties intermediate between the genotype- and the environment-focused scaling methods.

Plant Peroxisomes: Biogenesis and Function

Abstract: Peroxisomes are eukaryotic organelles that are highly dynamic both in morphology and metabolism. Plant peroxisomes are involved in numerous processes, including primary and secondary metabolism, development, and responses to abiotic and biotic stresses. Considerable progress has been made in the identification of factors involved in peroxisomal biogenesis, revealing mechanisms that are both shared with and diverged from non-plant systems. Furthermore, recent advances have begun to reveal an unexpectedly large plant peroxisomal proteome and have increased our understanding of metabolic pathways in peroxisomes. Coordination of the biosynthesis, import, biochemical activity, and degradation of peroxisomal proteins allows for highly dynamic responses of peroxisomal metabolism to meet the needs of a plant. Knowledge gained from plant peroxisomal research will be instrumental to fully understanding the organelle’s dynamic behavior and defining peroxisomal metabolic networks, thus allowing the development of molecular strategies for rational engineering of plant metabolism, biomass production, stress tolerance, and pathogen defense.

Conservation tillage and depth stratification of porosity and soil organic matter

Abstract: Pores and organic matter take a multitude of forms in soil and their characteristics change in space and time following a change in tillage practices as a new “steady state” is approached. Information on the variation with depth (stratification) in the characteristics of pores and organic matter and the rates of change in these characteristics is vital to interpreting the short- and long-term impacts of a reduction of tillage on the productivity and hydrology of agricultural soils. This information is also of value in estimating the effect of a reduction in tillage on the sequestration of carbon in agricultural soils. Recent literature comparing conventional tillage (CT) with no-till (NT) in temperate agroecosystems with varying soil textures and climates was reviewed for the purpose of assessing rates of change in the magnitude and stratigraphy of bulk density, porosity, pore size classes, organic matter content and organic matter fractions. The influence of tillage on bulk density, macroporosity and organic matter content was found to be documented more extensively than the effects on pore size distribution, soil organic matter fractions and their interactions at different soil depths. Many of the reports documenting tillage-induced changes in soil porosity and organic matter were based on measurements at a specific time after initiating the tillage trial. Results obtained by different investigators were found to be most consistent when measurements were made ≥15 years after initiating the tillage trial. Data from different studies were used to generalize trends in pore and organic matter characteristics with depth and time. However, few studies provided measurements that permitted accurate prediction of either the rates of change or the maximum change that will occur following a change from CT to NT. Future research must enhance our ability to make these predictions if we wish to garner a better understanding of the effects of NT on the quality and productivity of agricultural soils and their ability to sequester carbon.

Recent developments in understanding the regulation of starch metabolism in higher plants

Abstract: This article reviews current knowledge of starch metabolism in higher plants, and focuses on the control and regulation of the biosynthetic and degradative pathways. The major elements comprising the synthetic and degradative pathways in plastids are discussed, and show that, despite present knowledge of the core reactions within each pathway, understanding of how these individual reactions are co-ordinated within different plastid types and under different environmental conditions, is far from complete. In particular, recently discovered aspects of the fine control of starch metabolism are discussed, which indicate that a number of key reactions are controlled by post-translational modifications of enzymes, including redox modulation and protein phosphorylation. In some cases, enzymes of the pathway may form protein complexes with specific functional significance. It is suggested that some of the newly discovered aspects of fine control of the biosynthetic pathway may well apply to many other proteins which are directly and indirectly involved in polymer synthesis and degradation.