To maintain a symbiotic balance, leguminous plants have a systemic regulatory system called autoregulation of nodulation (AUT). Since AUT is schematically similar to systemic resistance found in plant-pathogen interactions, we examined the effects of methyl jasmonate (MeJA) or methyl salicylate (MeSA) on nodulation in Lotus japonicus. Shoot-applied MeJA strongly suppressed nodulation in the wil...

Mixed cultures of several Azospirillum and Rhizobium trifolii strains caused either an inhibition or stimulation of nodule formation on plant hosts as compared with nodulation of plants inoculated with R. trifolii alone. Azospirillum strains affected the nodulation process at a precise cell ratio (R. trifolii/Azospirillum cells) and time of inoculation. All Azospirillum strains used showed a va...

Mechanisms inhibiting legume nodulation by low soil pH, although highly prevalent and economically significant, are poorly understood. We addressed this in soybean (Glycine max) using a combination of physiological and genetic approaches. Split-root and grafting studies using an autoregulation-of-nodulation-deficient mutant line, altered in the autoregulation-of-nodulation receptor kinase GmNAR...

We report the isolation and characterization of a new Medicago truncatula hyper-nodulation mutant, designated sunn (super numeric nodules). Similar to the previously described ethylene-insensitive mutant sickle, sunn exhibits a 10-fold increase in the number of nodules within the primary nodulation zone. Despite this general similarity, these two mutants are readily distinguished based on anato...

We propose that nodule formation is mediated by eicosanoids in insects. Nodulation is the temporally and quantitatively predominant cellular defense response to bacterial infection in insects and other invertebrates. Inhibition of eicosanoid biosynthesis in larvae of the tobacco hornworm Manduca sexta immediately prior to intrahemocoelic infections with the bacterium Serratia marcescens strongl...

Although Cu is phytotoxic at Cu(2+) activities as low as 1-2 microM, the effect of Cu(2+) on the nodulation of legumes has received little attention. The effect of Cu(2+) on nodulation of cowpea (Vigna unguiculata (L.) Walp. cv. Caloona) was examined in a dilute solution culture system utilising a cation exchange resin to buffer solution Cu(2+). The nodulation process was more sensitive to incr...

Nodulation, nodule development and senescence directly affects nitrogen fixation efficiency, and previous studies have shown that inhibition of some cysteine proteases delay nodule senescence, so their nature inhibitors, cystatin genes, are very important in nodulation, nodule development, and senescence. Although several cystatins are actively transcribed in soybean nodules, their exact roles ...

Host legumes control root nodule numbers by sensing external and internal cues. A major external cue is soil nitrate, whereas a feedback regulatory system in which earlier formed nodules suppress further nodulation through shoot-root communication is an important internal cue. The latter is known as autoregulation of nodulation (AUT), and is believed to consist of two long-distance signals: a r...

Nodulation is the first, and qualitatively predominant, cellular defense reaction to bacterial infections in insects. We tested the hypothesis that eicosanoids also mediate nodulation reactions to bacterial challenge in adults of a social insect, the honey bee, Apis mellifera. Treating newly-emerged experimental bees with the eicosanoid biosynthesis inhibitor, dexamethasone, impaired nodulation...

Compatible rhizobia strains are essential for nodulation and biological nitrogen fixation (BNF) of hairy vetch (Vicia villosa Roth, HV). We evaluated how past HV cultivation affected nodulation and BNF across host genotypes. Five groups of similar HV genotypes were inoculated with soil dilutions from six paired fields, three with 10-year HV cultivation history (HV+) and three with no history (H...