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Nodulation is controlled by a variety of processes, both external (heat, acidic soils, drought, nitrate) and internal (autoregulation of nodulation, ethylene). Autoregulation of nodulation controls nodule numbers per plant through a systemic process involving the leaf. Leaf tissue senses the early nodulation events in the root through an ...
Nod factor. The structure of the major Nod factor produced by Sinorhizobium meliloti. Nod factors ( nodulation factors or NF ), are signaling molecules produced by soil bacteria known as rhizobia in response to flavonoid exudation from plants under nitrogen limited conditions. Nod factors initiate the establishment of a symbiotic relationship ...
Endophyte. Transmission electron microscope image of a cross section through a soybean ( Glycine max) root nodule. The nitrogen fixing bacteria, Bradyrhizobium japonicum, infects the roots and establishes a symbiosis. This high magnification image shows part of a cell with single bacteroid (bacterium-like cell or modified bacterial cell) within ...
Actinorhizal plants are distributed within three clades, [1] and are characterized by nitrogen fixation. [2] They are distributed globally, and are pioneer species in nitrogen-poor environments. Their symbiotic relationships with Frankia evolved independently over time, [3] and the symbiosis occurs in the root nodule infection site.
The partner choice hypothesis proposes that the plant uses prenodulation signals from the rhizobia to decide whether to allow nodulation, and chooses only noncheating rhizobia. There is evidence for sanctions in soybean plants, which reduce rhizobium reproduction (perhaps by limiting oxygen supply) in nodules that fix less nitrogen.
Plant hormones control all aspects of plant growth and development, including embryogenesis, [1] the regulation of organ size, pathogen defense, [2] [3] stress tolerance [4] [5] and reproductive development. [6] Unlike in animals (in which hormone production is restricted to specialized glands) each plant cell is capable of producing hormones.
Stele (biology) In a vascular plant, the stele is the central part of the root or stem [1] containing the tissues derived from the procambium. These include vascular tissue, in some cases ground tissue ( pith) and a pericycle, which, if present, defines the outermost boundary of the stele. Outside the stele lies the endodermis, which is the ...
Lawmakers in Alabama passed legislation that could lead to the prosecution of librarians under the state’s obscenity law for providing minors with “harmful” materials. The bill, approved 72 ...