How many peas in a pod? Legume genes responsible for mutualistic symbioses underground.
The nitrogen-fixing symbiosis between legume plants and Rhizobium bacteria is the most prominent plant-microbe endosymbiotic system and, together with mycorrhizal fungi, has critical importance in agriculture. The introduction of two model legume species, Lotus japonicus and Medicago truncatula, has enabled us to identify a number of host legume genes required for symbiosis. A total of 26 genes have so far been cloned from various symbiotic mutants of these model legumes, which are involved in recognition of rhizobial nodulation signals, early symbiotic signaling cascades, infection and nodulation processes, and regulation of nitrogen fixation. These accomplishments during the past decade provide important clues to understanding not only the molecular mechanisms underlying plant-microbe endosymbiotic associations but also the evolutionary aspects of nitrogen-fixing symbiosis between legume plants and Rhizobium bacteria. In this review we survey recent progress in molecular genetic studies using these model legumes.
Kouchi
Hiroshi
H
Department of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan. kouchih@nias.affrc.go.jp
Imaizumi-Anraku
Haruko
H
Hayashi
Makoto
M
Hakoyama
Tsuneo
T
Nakagawa
Tomomi
T
Umehara
Yosuke
Y
Suganuma
Norio
N
Kawaguchi
Masayoshi
M
D007887:Fabaceae / Q000235:genetics* / Q000382:microbiology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D009586:Nitrogen Fixation; D055170:Plant Root Nodulation / Q000235:genetics*; D012231:Rhizobium / Q000502:physiology*; D015398:Signal Transduction; D013559:Symbiosis / Q000235:genetics*