|Other titles||Nodule bacteria of legumes.|
|Statement||by Marcos Mondejar Alicante.|
|LC Classifications||QR113 .A5 1923|
|The Physical Object|
|Pagination||1 p. l., p. 27-52, 93-110, 1 l., 4 pl. :|
|Number of Pages||110|
|LC Control Number||26009692|
A legume (/ ˈ l ɛ ɡ j uː m, l ə ˈ ɡ j uː m /) is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as dry grain, the seed is called a s are grown agriculturally, primarily for human consumption, for livestock forage and silage, and as soil-enhancing green -known legumes include alfalfa, clover, beans, peas, chickpeas. adshelp[at] The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86ACited by: 3. Nov. 26, — Peas and other legumes develop spherical or cylindrical structures -- called nodules -- in their roots to establish a mutually beneficial relationship with bacteria that convert. Symbiosis between legumes and Rhizobium bacteria leads to the formation of root nodules where bacteria in the infected plant cells are converted into nitrogen-fixing bacteroids. Nodules with a persistent meristem are indeterminate, whereas nodules without meristem are determinate. The symbiotic plant cells in both nodule types are polyploid because of several cycles of .
Legumes form a symbiosis with nodule-inducing bacteria. Initially it was thought that the nodules of legumes (Fig. ) were caused by a plant disease, until their function in N 2 fixation was recognized by Hermann Hellriegel (Germany) in He found that beans containing these nodules were able to grow without nitrogen fertilizer. Bacteroid differentiation was first described in by Beijerinck as bacteria transforming from rod-shaped to Y-shaped cells ().The stages of development have been described at an ultrastructural level for several Rhizobium species (e.g. 2, 3, 4).The bacteria infect the nodule through an infection thread and enter the cytoplasm of plant cells in an endocytic-like process. tent, cell size, and viability. Using recombinant Rhizobium strains nodulating both legume types, we show that bacteroid differen-tiation is controlled by the host plant. Plant factors present in nodules of galegoid legumes but absent from nodules of nongale-goid legumes block bacterial cell division and trigger endoredu-. Biological nitrogen fixation has essential role in N cycle in global ecosystem. Several types of nitrogen fixing bacteria are recognized: the free-living bacteria in soil or water; symbiotic bacteria making root nodules in legumes or non-legumes; associative nitrogen fixing bacteria that resides outside the plant roots and provides fixed nitrogen to the plants; endophytic nitrogen fixing.
Root infection is normally coordinated with nodule morphogenesis and usually involves the development of infection threads (ITs), plant-made tube-like structures formed by invagination of the plant cell membrane and the biosynthesis of plant cell wall along the growing invagination ().The bacteria grow along the developing ITs, which grow between and through plant cells, eventually . Plant growth and N content are increased with an external N supply in both legume and non-legume plants, but the dependence on this supply is stronger in non-legumes. The increase in any form of N in soil or nutrient solution reduces the number of root nodules and N 2 fixation rates [ 25, 26 ]. Over the last several decades, there have been a large number of studies done on the genetics, biochemistry, physiology, ecology, and agronomics of the bacteria forming nitrogen-fixing symbioses with legumes. These bacteria, collectively referred to as the rhizobia, are taxonomically and. nodules are visible within 21 to 28 days from emergence of the plant. The time from planting to the appearance of nodules varies depending on plant growth and availability of mineral nitrogen in the soil. Nodules differ in shape, size, color, texture, and location. Their shape and location depend largely on the host legume.