Elongation and Gravireactivity of Roots from an Agravitropic Maize Mutant: Implications of Growth Inhibitors

Growth of agravitropic (AGT) mutant (c.v. Kys) maize roots was significantly higher in comparison to that of two normal gravitropic cultivar roots. Vertical halfdecapitated roots bent towards the remaining half tip. This result can be explained by the fact that cap cells produced growth inhibitors (GI) moving in basipetal direction. The curvatures of half-decapitated roots in Kys AGT root were significantly smaller than in normal cultivar root. One essential consequence of this AGT mutation was brought by low GI content inside the extension zon

Neutral low-dimensional assemblies of a Mn(III) schiff base complex and octacyanotungstate(V) : synthesis, characterization, and magnetic properties

International audienceTwo novel low-dimensional molecular magnetic materials were prepared by the self-assembly of 3d- and 5d-metal complexes. These are the first neutral heterobimetallic cyanobridged compounds involving one anisotropic Mn(III) Schiff base complex and one octacyanotungstate(V) per molecular unit. A slow diffusion of the constituents’ solutions leads to the formation of the 0D crystalline complex 1, due to coordination of a water molecule to the Mn center, which prevents polymer formation. A rapid mixing of reagents results in the precipitation of the microcrystalline powder of complex 2, which based on the totality of experimental data, possesses a 1D polymeric structure. The magnetic studies have shown that antiferromagnetic exchange interactions prevail in 1 (J/kB = −13.1(7) K, D = −3.0(1.3) K, zJ' = −0.16(20) K and gav = 2.00(1)); while the presence of the significant intramolecular Mn(III)–W(V) ferromagnetic coupling through cyanide bridge is characteristic for 2 (J/kB = 46.1(5) K, gMn = 2.11(3), fixed gW = 2.0). Due to the weak interchain interactions, zJ′/kB = −0.8(2) K, and compound 2 is a metamagnet with the Néel temperature of 9.5 K undergoing a spin-flip transition at 2 kOe. The slow magnetization dynamics of 2 were investigated at a DC field of 0 and 2 kOe, giving the values of τ0 32(15) and 36(15) ps, respectively, well within the range typical for single-chain magnets (SCMs). The respective ∆τ/kB values were 48.4(1.2) and 44.9(1.0) K

Root georeaction affected by exo-β-D-(l,3)-glucanase

Two hour pretreatment with exo-β-D-(l,3)-glucanase cause (at a concentration of 0.4 unit/ml) significant stimulation of the georeaction of maize apical root segments, horizontally placed for 7 hr. Implications of this enzyme effect on cell wall extension are discusse

Effect of the light on adenine nucleotide content of georeacting maize roots

Apical segments from maize roots of LG 11 and Orla 264 varieties georeacted, at least for the first few hours, only in light, while those of the Anjou 210 variety were georeactive both in light and darkness. The energy charge in the apical end of the two light geo-sensitive (LG and Orla) maize roots significantly increased in the light. In contrast, in Anjou root tips, the energy charge was already high in the dark and did not change significantly after light exposure. The time course of light-induced changes in adenine nucleotide contents in root tips was compared with varietal differences in georeactivity in light and darkness. The present data corroborate the hypothesis that a high energy state in the root tip is a prerequisite for the expression of the root reaction to gravit