Weight-induced radial growth in plant stems depends on PIN3.

How multiple growth programs coordinate during development is a fundamental question in biology. During plant stem development, radial growth is continuously adjusted in response to longitudinal-growth-derived weight increase to guarantee stability. Here, we demonstrate that weight-stimulated stem radial growth depends on the auxin efflux carrier PIN3, which, upon weight increase, expands its cellular localization from the lower to the lateral sides of xylem parenchyma, phloem, procambium, and starch sheath cells, imposing a radial auxin flux that results in radial growth.

Systems genetic analysis of lignin biosynthesis in Populus tremula.

The genetic control underlying natural variation in lignin content and composition in trees is not fully understood. We performed a systems genetic analysis to uncover the genetic regulation of lignin biosynthesis in a natural 'SwAsp' population of aspen (Populus tremula) trees. We analyzed gene expression by RNA sequencing (RNA-seq) in differentiating xylem tissues, and lignin content and composition using Pyrolysis-GC-MS in mature wood of 268 trees from 99 genotypes.

The effect of nitrogen source and levels on hybrid aspen tree physiology and wood formation.

Nitrogen can be taken up by trees in the form of nitrate, ammonium and amino acids, but the influence of the different forms on tree growth and development is poorly understood in angiosperm species like Populus. We studied the effects of both organic and inorganic forms of nitrogen on growth and wood formation of hybrid aspen trees in experimental conditions that allowed growth under four distinct steady-state nitrogen levels. Increased nitrogen availability had a positive influence on biomass accumulation and the radial dimensions of both xylem vessels and fibers, and a negative influence on wood density.

Developmental trajectories of school-beginners' ability self-concept, intrinsic value and performance in mathematics.

Background: Although research clearly demonstrates the importance of motivation in mathematics learning, relatively little is known about the developmental dynamics between different facets of mathematics motivation and performance, especially in the early years of schooling.

Aims: In a longitudinal setting, we examined (1) how children's ability self-concept and intrinsic value in mathematics change over time during their first 3 years in school, (2) how those changes relate to each other and (3) how they connect with mathematics performance.

Sample: The participants were 285 Finnish school-beginners (52.

Histochemical Detection of Peroxidase and Laccase Activities in Populus Secondary Xylem.

Peroxidases (PRXs) and laccases (LACs) are enzymes involved in catalyzing the oxidation of the lignin monomers to facilitate lignin polymerization. However, due to the large number of genes composing these two families of enzymes, many details regarding their specific localization are only partially understood. Here, we present a fast and easy histochemical method that makes use of the artificial substrate 3,3',5,5'-tetramethylbenzidine (TMB) to visualize PRX and LAC activities in the hybrid aspen (Populus tremula x P.