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Abstract: Legumes are members of the family Fabaceae or Leguminosae and include economically important grain legumes, oilseed crops, forage crops, shrubs, and tropical or subtropical trees. Legumes are a rich [...]

Abstract: Sequence data for 2 non-coding regions of the chalcone isomerase gene were analyzed to study the genetic architecture of common bean (Phaseolus vulgaris L.). One region corresponded to the [...]

Interseeding nontraditional, cool-season legumes into bermudagrass [Cynodon dactylon (L.) Pers.] paddocks was evaluated as an approach to increasing the quality and duration of forage production and replacing a portion of the N fertilizer required in the southern Great Plains. We compared the effects of interseeding either grass pea (Lathyrus sativa L. 'AC-Greenfix') or lentil (Lens culinaris Med. 'Indianhead') with N fertilizer rates of 0, 45, or 90 kg [ha.sup.-1] N. All plots received 60 kg [P.sub.2][O.sub.5] [ha.sup.-1] in early March. The legume and fertilizer treatments were imposed in mid-March during 2001, 2002, and 2003. Forage samples were clipped from 0.25 [m.sup.-2] quadrats on five sampling dates between I May and 15 July each year. Yield, N concentration, species composition, and in vitro digestible dry matter (IVDDM) were determined. Year, sampling date, and treatment showed significant (P < 0.05) effects, as did the two-way interactions between all three factors. Total end-of-season standing dry matter of bermudagrass and grass pea was 5550 [+ or -] 423 (SEM) kg [ha.sup.-1], which was similar to biomass production with 45 kg [ha.sup.-1] N (5305 [+ or -] 570 kg [ha.sup.-1]) and less than that produced with 90 kg [ha.sup.-1] N (7785 [+ or -] 725 kg [ha.sup.-1]). Forage N and IVDDM concentrations for the grass pea treatment were 34 and 6% higher than for bermudagrass, but N and IVDDM concentrations of the forage mixture were intermediate between the higher N rates. Although additional studies are needed to optimize management for the interseeded legumes, we conclude that this practice can improve the quality and duration of bermudagrass forage production in this region.

Abstract: A PCR approach with degenerate primers designed from conserved NBS-LRR (nucleotide binding site--leucine-rich repeat) regions of known disease-resistance (R) genes was used to amplify and clone homologous sequences from [...]

Most land plants can form a root symbiosis with arbuscular mycorrhizal (AM) fungi for assimilation of inorganic phosphate from the soil. In contrast, the nitrogen-fixing root nodule symbiosis is almost completely restricted to the legumes. The Finding that the two symbioses share common signaling components in legumes suggests that the evolutionarily younger nitrogen-fixing symbiosis has recruited functions from the more ancient AM symbiosis. The recent advances in cloning of the genes required for nodulation and AM symbioses from the two model legumes, Medicago truncatula and Lotus japonicus, provide a unique opportunity to address biological questions pertaining to the evolution of root symbioses in plants. Here, we report that nearly all cloned legume genes required for nodulation and AM symbioses have their putative orthologs in nonlegumes. The orthologous relationship can be clearly defined on the basis of both sequence similarity and microsyntenic relationship. The results presented here serve as a prelude to the comparative analysis of orthologous gene function between legumes and nonlegumes and facilitate our understanding of how gene functions and signaling pathways have evolved to generate species--or family-specific phenotypes.

Nuclear-cytoplasmic partitioning and traffic between cytoplasmic and nuclear compartments are fundamental processes in eukaryotic cells. Nuclear pore complexes mediate transport of proteins, RNAs and ribonucleoprotein particles in and out of the nucleus. Here we present positional cloning of a plant nucleoporin gene, Nup133, essential for a symbiotic signal transduction pathway shared by Rhizobium bacteria and mycorrhizal fungi. Mutation of Nup133 results in a temperature sensitive nodulation deficient phenotype and absence of mycorrhizal colonization. Root nodules developing with reduced frequency at permissive temperatures are ineffective and electron microscopy show that Rhizobium bacteria are not released from infection threads. Measurement of ion fluxes using a calcium-sensitive dye show that Nup133 is required for the [Ca.sup.2+] spiking normally detectable within minutes after application of purified rhizobial Nod-factor signal molecules to root hairs. Localization of NUP133 in the nuclear envelope of root cells and root hair cells shown with enhanced yellow fluorescent protein fusion proteins suggests a novel role for NUP133 nucleoporins in a rapid nuclear-cytoplasmic communication after host-plant recognition of symbiotic microbes. Our results identify a component of an intriguing signal process requiring interaction at the cell plasma membrane and at intracellular nuclear and plastid organelle-membranes to induce a second messenger. legume symbiosis | nucleoporin | nuclear pore | plant-microbe interaction

Legumes are simultaneously one of the largest families of crop plants and a cornerstone in the biological nitrogen cycle. We combined molecular and phylogenetic analyses to evaluate genome conservation both within and between the two major clades of crop legumes. Genetic mapping of orthologous genes identifies broad conservation of genome macrostructure, especially within the galegoid legumes, while also highlighting inferred chromosomal rearrangements that may underlie the variation in chromosome number between these species. As a complement to comparative genetic mapping, we compared sequenced regions of the model legume Medicago truncatula with those of the diploid Lotus japonicus and the polyploid Glycine max. High conservation was observed between the genomes of M. truncatula and L. japonicus, whereas lower levels of conservation were evident between M. truncatula and G. max. In all cases, conserved genome microstructure was punctuated by significant structural divergence, including frequent insertion/deletion of individual genes or groups of genes and lineage-specific expansion/contraction of gene families. These results suggest that comparative mapping may have considerable utility for basic and applied research in the legumes, although its predictive value is likely to be tempered by phylogenetic distance and genome duplication.

Byline: Won Kyung Lee (1), Toru Tokuoka (2), Kweon Heo (1) Keywords: Caesalpinioideae; Echinosophora; Embryology; Molecular phylogeny; rbcL; Sophora; trnL Intron Abstract: Although Echinosophora Nakai has been known as a monotypic and endemic genus of Papillionoideae of Fabaceae in Korea, it has been controversial whether it is distinct from or merged with Sophora. To resolve this matter, we conducted molecular phylogenetic analyses using nucleotide sequence data from the plastid rbcL gene and trnL (UAA) intron. Parsimony analysis, using a total of 53 taxa of the Papillionoideae (including E. koreensis [Nakai] Nakai and several species of Sophora and related genera) and using 20 taxa of Caesalpinioideae and Mimosoideae as outgroups, showed that, although the examined species of Sophora are split into two clades, E. koreensis formed a common clade with S. tomentosa (the type species of the genus) and S. flavescens. E. koreensis therefore should be treated as S. koreensis Nakai, and the generic name Echinosophora be eliminated. We also investigated the embryology of S. koreensis (=E. koreensis) and S. flavescens and found that no differences existed between them. Our molecular study, like other studies, strongly suggested that Sophora is polyphyletic. In this study we presented a summary of embryological features of the core Sophora for future critical comparison with related and unrelated taxa. Author Affiliation: (1) Division of Applied Plant Sciences, Kangwon National University, 200-701, Chuncheon, Korea (2) Department of Natural Environmental Sciences, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan Article History: Registration Date: 11/03/2004 Received Date: 31/10/2003 Accepted Date: 01/03/2004 Online Date: 09/04/2004

In wild-type Rhizobium leguminosarum, the sitABCD operon specifies a [Mn.sup.2+] transporter whose expression is severely reduced in cells grown in the presence of this metal. Mutations in the R. leguminosarum gene, mur (manganese uptake regulator), whose product resembles the Fur transcriptional regulator, cause high-level expression of sitABCD in the presence of [Mn.sup.2+]. In gel-shift mobility assays, purified R. leguminosarum Mur protein bound to at Least two regions near the sitABOD promoter region, although this DNA has no conventional consensus Fur-binding sequences (fur boxes). Thus, in contrast to [gamma]-proteobacteria, where Fur binds [Fe.sup.2+], the R. leguminosarum Fur homologue, Mur, act as a [Mn.sup.2]-responsive transcriptional regulator.

Synthesis of the Rhizobium leguminesarum [NiFe] hydrogenase requires the participation of 16 accessory genes (hupCDEFGHIJKhypABFCDEX) besides the genes encoding the structural proteins (hupSL). Transcription of hupSL is controlled by a -24/-1 2-type promoter ([P.sub.1]), located upstream of hupS and regulated by NifA. In this work, a second -24/-1 2-type promoter ([P.sub.3]), located upstream of the hupG gene and transcribing hupGHU genes in R. leguminosarum pea (Pisum sativum L.) bacteroids, has been identified in the hup gene cluster. Promoter [P.sub.3] was also active in R. leguminesarum free-living cells, as evidenced by genetic complementation of hydrogenase mutants. Both NifA and NtrC activated Ps expression in the heterologous host Klebsiella pneumoniae. Also, [P.sub.3] activity was highly stimulated by K. pneumoniae NifA in Escherichia coil. This NifA activation of [P.sub.3] expression only required the [[sigma].sup.54]-binding site, and it was independent of any cis-acting element upstream of the 54 box, which suggests a direct interaction of free NifA with the RNA polymerase holoenzyme. [P.sub.3]-dependent hupGHIJ expression in pea nodules started in interzone II/III, spanned through nitrogen-fixing zone III, and was coincident with the NifA-dependent nifH expression pattern. However, [P.sub.3] was dispensable for hupGHIJ transcription and hydrogenase activity in pea bacteroids due to transcription initiated at [P.sub.1]. This fact and the lack of an activator recruitment system suggest that [P.sub.3] plays a secondary role in symbiotic hupGHIJ expression.

Acacia aroma and A. macracantha are closely related species that inhabit northern and central Argentina. The reproductive barriers between them seem to be weak. They exhibit low genetic differentiation, high levels of interspecific gene flow, and extensive areas of sympatry. Isoenzymatic approaches were used to evaluate the population structure and mating system parameters in natural Argentine populations of A. aroma and A. macracantha and to provide new tools for the analysis of relationships between these two species. All studied populations had high levels of genetic variability and no significant departures from Hardy-Weinberg expectations, but the two species did not differ from each other. Most variability occured within populations. Mating system analysis showed high levels of outcrossing, no biparental inbreeding, and a high probability that individuals within progeny arrays are full rather than half sibs. In all A. aroma and A. macracantha populations, polymorphic loci had the same allelic variants, and no geographic or genetic isolation between species was found. The results favor the hypothesis that these two entities represent a single polymorphie species rather than two distinct species. Key words: Acacia; Argentina; Fabaceae; genetic variability; isozymes; mating system parameters; population structure.

We used nucleotide sequences from the internal transcribed spacers and 5.85 gene of nuclear ribosomal DNA to test competing phylogenetic and biogeographic hypotheses in Gleditsia. Eleven of 13 Gleditsia species were sampled, along with two species of its sister genus, Gymnocladus. Analyses of ITS data and of a combined data set that included sequences of ITS and two chloroplast genes supported several conclusions that were interpreted in light of fossil data and current legume phylogeny. Gleditsia and Gymnocladus appear to have originated in eastern Asia during the Eocene. Eastern North American species of both genera most likely evolved from ancestors that migrated across the Bering land bridge, but the eastern Asian/eastern North American disjunction appears to be much older in Gymnocladus than in Gleditsia. Gleditsia amorphoides, from temperate South America, is sister to the rest of the genus, suggesting early long-distance dispersal from Asia. The remainder of Gleditsia is divided into three unresolved clades, possibly indicating a split early in the evolution of the genus. Two of those clades contain only Asian species, and one contains Asian and North American species. The North American species, Gleditsia triacanthos and Gleditsia aquatica, are polymorphic and paraphyletic with respect to their ITS and cpDNA sequences, which suggests recent diversification. Key words: biogeography; Gleditsia; Gymnocladus; internal transcribed spacer; Leguminosae; molecular phylogeny; ribosomal DNA.

Legume seed development is characterized by progressive differentiation of organs and tissues resulting in development gradients. Transgenic legumes with changed metabolic pathway and seed composition provide suitable models to study pathway regulation and metabolic control.