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Leguminous plants can enter into root nodule symbioses with nitrogen-fixing soil bacteria known as rhizobia. An intriguing but still poorly understood property of the symbiosis is its host specificity, which is controlled at multiple levels involving both rhizobial and host genes. It is widely believed that the host specificity is determined by specific recognition of bacterially derived Nod factors by the cognate host receptor(s), Here we describe the positional cloning of two soybean genes Rj2 and Rfg1 that restrict nodulation with specific strains of Bradyrhizobium japonicum and Sinorhizobium fredii, respectively. We show that Rj2 and Rfg1 are allelic genes encoding a member of the Toll-interleukin receptor/nucleotide-binding site/leucine-rich repeat (TIR-NBS-LRR) class of plant resistance (R) proteins. The involvement of host R genes in the control of genotype-specific infection and nodulation reveals a common recognition mechanism underlying symbiotic and pathogenic host-bacteria interactions and suggests the existence of their cognate avirulence genes derived from rhizobia. This study suggests that establishment of a root nodule symbiosis requires the evasion of plant immune responses triggered by rhizobial effectors. soybean | nodulation | nitrogen fixation | defense doi/ 10.1073/pnas.1011957107

In most angiosperms, the endosperm develops before the embryo, but with harmony between the two structures until final seed formation. In an embryological study, we show that inbreeding depression causes disharmony in development of the two structures in two Leguminosae shrubs, Cytisus multiflorus and C. striatus. Our main objective was to test the causes of self- sterility in the two species by comparing the embryological development of the self seeds with that of cross seeds. In developing selfed seeds of C. multiflorus, the embryo reaches at most the globular stage and never forms mature seeds, while in C. striatus a few mature selfed seeds are formed. In both species, the main cause of abortion of developing selfed seeds is diminished endosperm development (low values of the ratio of endosperm to embryo), which triggers collapse of the endosperm and embryo. The results indicate that self-sterility in C. striatus is postzygotic because of strong, early inbreeding depression, while in C. multiflorus there exists a mixed pre- and postzygotic mechanism; the prezygotic mechanism causes rejection of some self-pollen tubes in the style/ovary, and the early inbreeding depression triggers abortion of fertilized ovules that escaped that action. Key words: abortion; Cytisus multiflorus; Cytisus striatus; embryogeny failures; inbreeding depression; late-acting self-incompatibility; Leguminosae; Mediterranean region; self-sterility. doi: 10.3732/ajb.0800332

Dry bean (Phaseolus vulgaris L.) is highly susceptible to drought stress, and drought affects 60% of global bean production. We evaluated elite exotic dry bean germplasm derived from the Mesoamerican gene pool for drought tolerance, yield, and adaptation to western Nebraska during 2006 and 2007 at three research sites. Seven tropical lines were evaluated with two great northern cultivars (Matterhorn and BerylR) and one pinto cultivar (Bill-Z) serving as checks. Adjacent nonstressed (NS) and drought-stressed (DS) blocks were evaluated. Within each block, the selected lines were assigned to experimental units using a randomized complete block design with four replications at each location. On average, yield was 60% less, 100-seed weight was 19.2% lower, and maturity occurred 4 d earlier under DS than under NS conditions. Beryl-R, SER 22, and Matterhorn had the greatest average yield under both NS (3564, 3347, and 3440 kg [ha.sup.-1], respectively) and DS (1701, 1773, and 1584 kg [ha.sup.-1], respectively). These genotypes were also the most drought tolerant based on the drought susceptibility index (0.9, 0.8, and 0.9, respectively) and geometric mean (2462, 2436, and 2335, respectively). Based on these results, Matterhorn, Beryl-R, and SER 22 show the most promise for use in breeding for drought tolerance. doi: 10.2135/cropsci2008.12.0694

Microsatellite markers are useful genetic tools for a wide array of genomic analyses although their development is time-consuming and requires the identification of simple sequence repeats (SSRs) from genomic sequences. Screening of non-enriched, small-insert libraries is an effective method of SSR isolation that can give an unbiased picture of motif frequency. Here we adapt high-throughput protocols for the screening of plasmid-based libraries using robotic colony picking and filter preparation. Seven non-enriched genomic libraries from common bean genomic DNA were made by digestion with four frequently cutting restriction enzymes, double digestion with a frequently cutting restriction enzyme and a less frequently cutting restriction enzyme, or sonication. Library quality was compared and three of the small-insert libraries were selected for further analysis. Each library was plated and picked into 384-well plates that were used to create high-density filter arrays of over 18 000 clones each, which were screened with oligonucleotide probes for various SSR motifs. Positive clones were found to have low redundancy. One hundred SSR markers were developed and 80 were tested for polymorphism in a standard parental survey. These microsatellite markers derived from non-SSR-enriched libraries should be useful additions to previous markers developed from enriched libraries. Key words: DOR364, genomic microsatellites, plasmid clones, simple sequence repeats. Les microsatellites constituent des outils genetiques utiles pour une grande gamme d'analyses genomiques bien que leur developpement prenne du temps et necessite l'identification de sequences simples repetees (SSR) au sein des sequences genomiques. Le criblage de banques a inserts courts sans enrichissement prealable represente une methode efficace pour isoler des SSR, laquelle peut livrer un porkrait de la frequency des motifs qui soft sans biais. Dans ce travail, les auteurs adaptent des protocoles a haut debit pour robotiser le prelevement des colonies et la preparation des membranes au tours du criblage de banques de plasmides. Un jeu de sept banques genomiques non-enrichies preparees a partir de l'ADN genomique du haricot fragmente par sonication ou encore digere avec quatre enzymes coupant frequemment ou une double digestion avec ces enzymes et une enzyme coupant moms souvent. La quality de banques a ete comparee et trois des banques a inserts courts ont ete retenues pour analyse ulterieure. Chaque banque a ete etalee et les colonies disposees dans des plaques a 384 puns, lesquelles ont servi a preparer les membranes a haute density comprenant plus de 18 000 clones. Ces membranes ont ete ensuite criblees avec des sondes oligonucleotidiques pour les differents motifs SSR. Il a ete observe que les clones positifs presentaient une faible redundancy et 100 marqueurs SSR ont ete mis au point dont 80 ont ete testes pour le polymorphisme sur un jeu de parents. Ces microsatellites derives de banques non-enrichies devraient s'averer un ajout utile aux marqueurs developpes precedemment a partir de banques enrichies. Mots-cles : DOR364, microsatellites genomiques, clones plasmidiques, sequences simples repetees. [Traduit par la Redaction], Introduction Microsatellites are PCR-based markers that target simple sequence repeat (SSR) loci based on various repeat motifs that are evaluated for size polymorphisms with different electrophoretic systems (Powell et al. [...]

Expressed sequence tag (EST)-derived simple sequence repeat (eSSR) markers are important resources for gene discovery and comparative mapping aimed at crop improvement. In this study, we developed eSSR markers for Medicago truncatula and assessed their cross-species transferability. We detected 36847 non-redundant sequences ('unigenes') from 198 642 M. truncatula EST sequences. Mining of microsatellites from the 36 847 unigene sequences (representing ti 25.8 Mb) revealed 14 637 eSSRs in 11750 SSR-containing ESTs, and primer pairs were successfully designed for 4 636 (39.5%). Of the 14637 eSSRs, 82.6% were mononucleotide repeats and the rest (in descending order of abundance) were tri-, di-, penta-, and tetranucleotide repeats. When less stringent SSR detection criteria were used, the frequency of dinucleotide repeat motifs increased more than twofold, and the frequencies of di- (11%) and trinucleotide motifs (10.6%) were almost equal. This demonstrates that the eSSR frequency and distribution were related to the choice of search criteria. Forty-one randomly selected primer pairs were validated, and their transferability in three leguminous and three nonleguminous species was assessed. The markers showed a high level of transferability in the leguminous (53%-71%) and non-leguminous (33%-44%) species. The validation studies thus demonstrate the utility of the Medicago eSSRs in assessing genomic relationships in both leguminous and non-leguminous species. Key words: Medicago truncatula, unigene, EST-derived simple sequence repeats (eSSRs), transferability. Des microsatellites identifies au sein d'etiquettes de sequences exprimees (EST), connus sous le nom de marqueurs eSSR, sont des resources importantes en vue du clonage de genes et de la cartographie comparee visant l'amelioration genetique. Dans ce travail, les auteurs ont mis au point des marqueurs eSSR chez le Medicago truncatula et determine leur portabilite chez d' autres especes. Les auteurs ont detecte 36 847 unigenes au sein de 198 642 sequences EST provenant du M. truncatula. L'examen des 36847 unigenes, totalisant 25,8 Mb, a permis d'identifier 14637 (39,7 %) eSSR au sein de 11750 EST qui contenaient au moms un SSR. Il a ete possible de synthetiser des paires d'amorces pour 4636 (39,5 %) de ces eSSR. Des 14637 eSSR, 82,6 % etaient des suites mononucleotidiques, les autres etant (en ordee decroissant) des suites tri-, di-, penta- et tetranucleotidiques. L'emploi de criteres moms stricts pour la detection des SSR a permis de plus que doubler la frequence des suites dinucleotidiques et de rendre presque egales les proportions de motifs di- (11 %) et trinucleotidiques (10,6 %). Cela montre que la frequence et la distribution des eSSR soot liees au choix des criteres d'interrogation des banques. Au total, 41 paires d'amorces choisies au hasard ont ete validees et leur portabilite a ete examinee chez trois especes de legumineuses ainsi que chez trois autres especes. Les marqueurs ont affiche une grande portabilite tant chez les legumineuses (53-71 %) que chez les autres especes (33-44 %). Cette validation illustre l'utilite des eSSR de Medicago pour etudier les relations genomiques au sein des legumineuses et d'autres especes. Mots-cles : Medicago truncatula, unigene, microsatellites derives d'un EST (eSSR), portabilite. [Traduit par la Redaction], Introduction The legume family is the second most important food and forage source after the grass family. Within the legume family, one of the most studied species is Medicago truncatula, [...]

Iron and zinc are essential micronutrients for human health often found in insufficient quantities in the diet. Biofortification of seed crops has been undertaken to reduce micronutrient malnutrition. The objectives of this study were to identify variability for seed Fe, Zn, P, and phytic acid levels in an [F.sub.5:7] recombinant inbred line (RIL) population developed from a cross between AND696 and G19833, both common beans (Phaseolus vulgaris L.) of Andean origin. Quantitative trait loci (QTL) analysis was conducted with data from 2 yr and 2 P treatments with a previously described linkage map of AND696/ G19833. Significant environmental and genetic variability for Fe, Zn, and P levels was identified, and Fe and Zn levels were correlated (up to r = 0.53). Quantitative trait loci for seed Fe and Zn co-localized on three linkage groups (B1, B6, and B11). On B6, a QTL for Fe ([R.sup.2] = 0.36) was found at the same marker interval as a QTL for seed Zn ([R.sup.2] = 0.39), both derived from AND696. Quantitative trait loci for seed P were identified on six linkage groups and explained 17 to 55% of the total phenotypic variation depending on year and environment.

Grain (pulse) legumes could provide high nitrogen (N), late summer forage for stocker cattle in the southern Great Plains (SGP). This study evaluated the forage yield and nutritive value of tropical annual legumes that were relatively uncommon in the SGP, at a site (35040' N, 98000' W) in central Oklahoma. Included were cultivars of pigeon pea ([Cajanus cajan (L.) Millsp.], cv. GA-2), guar ([Cyamopsis tetragonoloba (L.) Taub.], cv. Kinman), cowpea ([Vigna unguiculata (L). Walp.], cv. Chinese red), and mung bean ([Vigna radiata (L.) Wilcz.], cv. Berkins), and grain soybean ([Glycine max (L.) Merr.] cv. Hutcheson) was used as a control. Seeds were inoculated and planted (60-cm row spacing at 10 seeds [m.sup.-1] row length) annually in mid-June 2003 through 2006. Aboveground samples were collected on six dates, from 45 to 120 d since planting. Soybean, pigeon pea, and guar averaged 3560, 3439, and 3321 kg [ha.sup.-1], while mung bean and cowpea averaged 2918 and 2405 kg [ha.sup.-1], respectively. Mung bean and cowpea accumulated the least N (70 and 65 kg N [ha.sup.-1]), while soybean, guar, and pigeon pea yielded 100, 93, and 77 kg N [ha.sup.-1], respectively. Digestibility of cowpea, mung bean, soybean, and guar were similar (757 to 825 g [kg.sup.-1]), while pigeon pea was least digestible (634 g [kg.sup.-1]). These pulse legumes could provide producers in the SGP with options other than soybean for generating forage or biological N.

Adzuki bean [Vigna angularis (Willd.) Ohwi & Ohashi] is cultivated in a wide range of agroecological environments from north to south China. An understanding of the genetic variation for crop adaptation facilitates plant breeding. A core germplasm of 231 accessions (selected from a representative collection of 3908 Chinese landraces) was evaluated at diverse locations in China in 1998 to (i) compare differences among sources of landraces for trait expression, (ii) identify underlying patterns of diversity, and (iii) characterize patterns of genetic adaptation across environments. Three-mode pattern analysis of phenology, yield and yield components, and plant height data identified six accession groups with various levels of cohesiveness. The greatest diversity occurred in the germplasm from the provinces of mid-north China, particularly the lower Yellow River basin, with a partial latitudinal separation of the accession origins in different groups. The most contrasting groups came, respectively, from south China (Sichuan-Anhui), characterized by late maturity and small seed size, and from north China (Liaoning--Heilongjiang), characterized by earliness and short habit. Analysis of the multilocation screening provided genotype x environment characterization of the accession groups and a capability to predict the most suitable groups for specific target environments and breeding objectives, thereby enabling plant breeders to make efficient and effective use of germplasm.

This analysis goes beyond many phylogenies in exploring how phylogenetic structure imposed by morphology, ecology, and geography reveals useful evolutionary data. A comprehensive range of such diversity is evaluated within tribe Indigofereae and outgroups from sister tribes. A combined data set of 321 taxa (over one-third of the tribe) by 80 morphological characters, 833 aligned nuclear ribosomal ITS/5.8S sites, and an indel data set of 33 characters was subjected to parsimony analysis. Notable results include the Madagascan dry forest Disynstemon resolved as sister to tribe Indigofereae, and all species of the large genus Indigofera comprise just four main clades, each diagnosable by morphological synapomorphies and ecological and geographical predilections. These results suggest niche conservation (ecology) and dispersal limitation (geography) are important processes rendering signature shapes to the Indigofereae phylogeny in different biomes. Clades confined to temperate and succulent-rich biomes are more dispersal limited and have more geographical phylogenetic structure than those inhabiting tropical grass-rich vegetation. The African arid corridor, particularly the Namib center of endemism, harbors many of the oldest Indigofera lineages. A rates analysis of nucleotide substitutions confirms that the ages of the oldest crown clades are mostly younger than 16 Ma, implicating dispersal in explaining the worldwide distribution of the tribe. Key words: biogeography; character evolution: dispersal limitation; Fabaceae; Indigofera; Indigofereae; Leguminosae; molecular phylogeny; rates analysis.

Little is known about the molecular mechanisms by which the embryo proper and suspensor of plant embryos activate specific gene sets shortly after fertilization. We analyzed the upstream region of the scarlet runner bean (Phaseolus coccineus) G564 gene to understand how genes are activated specifically within the suspensor during early embryo development. Previously, we showed that the G564 upstream region has a block of tandem repeats, which contain a conserved 10-bp motif ([GAAAAG.sup.C]/[sub.T]GAA), and that deletion of these repeats results in a loss of suspensor transcription. Here, we use gain-of-function (GOF) experiments with transgenic globular-stage tobacco embryos to show that only 1 of the 5 tandem repeats is required to drive suspensor-specific transcription. Fine-scale deletion and scanning mutagenesis experiments with I tandem repeat uncovered a 54-bp region that contains all of the sequences required to activate transcription in the suspensor, including the 10-bp motif (GAAAAGCGAA) and a similar 10-bp-like motif (GAAAAACGAA). Site-directed mutagenesis and GOF experiments indicated that both the 10-bp and 10-bp-like motifs are necessary, but not sufficient to activate transcription in the suspensor, and that a sequence (TTGGT) between the 10-bp and the 10-bp-like motifs is also necessary for suspensor transcription. Together, these data identify sequences that are required to activate transcription in the suspensor of a plant embryo after fertilization. promoter analysis | scarlet runner bean

Single nucleotide polymorphisms (SNPs) are the most common sequence difference found in plant genomes, yet they have not been widely exploited for producing molecular markers in common bean (Phaseolus vulgaris L.). The objective of this study was to develop a SNP assay based on a type of heteroduplex mismatch cleavage called EcoTILLING for molecular marker development in this important legume, and apply the assay (i) to the conversion of a sequence-characterized amplified region (SCAR) marker useful for selecting virus resistance (SR2) and (ii) to the screening of SNP polymorphisms in newly developed expressed sequence tag (EST)-based markers. The SNP assay involved heteroduplex mismatch cleavage by a single-strand specific nuclease 'CEL I' which was used to uncover two SNPs in the SR2 fragment and 22 SNPs in 37 candidate ESTs, some of which were used in segregation analysis. While developing the SNP techniques we tested several platforms, including LI-COR, nondenaturing polyacrylamide, and agarose gel detection. The agarose gel system was used for SNP genetic mapping in two common bean mapping populations, showing that heteroduplex cleavage is a useful technique for increasing molecular marker number for the crop. Examples are given of mapped SNP markers for the phytic acid pathway gene for myoinositol-1-phosphate synthase and a drought tolerance--related gene, S-adenosylmethionine decarboxylase.

The endangered Shivwits milkvetch, Astragalus ampullarioides, is a perennial, herbaceous plant. This Utah endemic was federally listed as endangered in 2001 because of its high habitat specificity and low numbers of individuals and populations. All habitat currently occupied by A. ampullarioides was designated as critical by the U.S. Fish and Wildlife Service in 2006 as a result of conservation litigation. We used AFLP markers to assess genetic differentiation among the seven extant populations and quantified genetic diversity in each. Six different AFLP markers resulted in 217 unambiguous polymorphic loci. We used multiple methods to examine any changes in population genetic structure in this species over time. Results indicate that A. ampullarioides had much higher gene flow among populations in the past, but has since fragmented into regional genetic units. These regions further fragmented genetically, and extant populations have differentiated through genetic drift. Populations had low levels of gene flow, even between geographically close populations. Rapid urban development reduces gene flow among regions and encroaches on populations of A. ampullarioides and remaining patches of unoccupied habitat. The genetic makeup of each of the extant populations should be carefully considered in management decisions such as population establishment or augmentation. Key words: AFLP; Astragalus ampullarioides; endemic; Fabaceae; population genetics; soil specific; Washington County, Utah; Utah; Zion National Park.

Genetic diversity in 20 elite blackgram (Vigna mungo (L.) Hepper) genotypes was studied using microsatellite and AFLP markers. Thirty-six microsatellite markers from azuki bean (Vigna angularis (Willd.) Ohwi & Ohashi) were successfully amplified across the 20 blackgram genotypes and 33 microsatellite markers showed polymorphism. A total of 137 microsatellite alleles were generated with an average of 4.1 alleles per locus. The number of alleles ranged from two to nine and the polymorphic information content value for the microsatellite markers varied from 0.10 to 0.87 with an average of 0.49. Microsatellite markers were highly informative and a combination of only three microsatellite markers (CEDG264, CEDG173, and CEDG044) was sufficient to discriminate all 20 blackgram genotypes. In the case of AFLP, 11 primer pairs generated 324 polymorphic marker fragments. The polymorphic information content values for AFLP primer combinations ranged from 0.21 to 0.34 with an average of 0.29. Similarity measures and clustering analyses were made using microsatellite and AFLP data separately. The resulting dendrograms distributed the 20 blackgram genotypes into five main clusters. The dendrograms were comparable with each other with the Mantel test between the cophenetic matrices of microsatellite data and AFLP data showing moderate correlation (r = 0.64). The results of the principal components analysis were well congruent with the dendrograms. In the dendrograms as well as in the principal components analyses, genotype Trombay wild (Vigna mungo var. silvestris) was placed separately from rest of the genotypes. This study demonstrated that the azuki bean microsatellite markers are highly polymorphic and informative and can be successfully used for genome analysis in blackgram. Results indicate that sufficient variability is present in the blackgram genotypes and would be helpful in the selection of suitable parents for breeding purposes and gene mapping studies. Key words: genetic diversity, blackgram, microsatellite markers, AFLP markers, genotype identification. La diversite genetique chez 20 genotypes elites du haricot mung a grains noirs (Vigna mungo (L.) Hepper) a ete etudiee a l'aide de microsatellites et de marqueurs AFLP. Trente-six marqueurs microsatellites provenant du haricot azuki (Vigna angularis (Wild.) Ohwi & Ohashi) ont amplifie avec succes chez les 20 genotypes elites du haricot mung a grains noirs et 33 de ceux-ci etaient polymorphes. Un ensemble de 137 alleles microsatellites ont ete observes pour une moyenne de 4,1 alleles par locus. Le nombre d'alleles variait entre deux et neuf tandis que l'indice de contenu d'information polymorphique pour ces marqueurs variait entre 0,10 et 0,87 pour une moyenne de 0,49. Les marqueurs microsatellites se sont averes tres informatifs et une combinaison de seulement trois marqueurs (CEDG264, CEDG173 et CEDG044) suffisait a distinguer les 20 genotypes. Dans le cas des AFLP, 11 paires d'amorces ont genere 324 fragments polymorphes. Les indices de contenu d'information polymorphique pour les AFLP allaient de 0,21 a 0,34 pour une moyenne de 0,29. Des mesures de similarite et des analyses de groupement ont ete effectuees a l'aide des donnees microsatellites et AFLP separement. Les dendrogrammes obtenus divisaient les 20 genotypes en cinq groupes principaux. Les dendrogrammes etaient semblables sur la base d'un test de Mantel effectue sur les matrices co-phenetiques des donnees microsatellites et AFLP, lequel montrait une correlation moderee (r = 0,64). Les resultats d'une analyse des composantes principales concordaient avec les dendrogrammes. Dans les dendrogrammes tout comme dans les analyses des composantes principales, le genotype Trombay wild (V. mungo var. silvestris) formait un groupe distinct des autres genotypes. Cette etude montre que les microsatellites du haricot azuki sont tres polymorphes et informatifs de sorte qu'ils sont utiles pour l'analyse du genome chez le haricot mung a grains noirs. Les resultats indiquent qu'une variabilite suffisante est presente au sein de ces genotypes et qu'elle serait utile en vue de la selection de parents appropries pour des fins de selection varietale et des etudes de cartographie genetique. Mots-cles: diversite genetique, haricot mung a grains noirs, marqueurs microsatellites, marqueurs AFLP, identification des genotypes. [Traduit par la Redaction], Introduction Grain legumes are among the most important crops in many countries, since they provide one third of the dietary protein for human consumption. Blackgram (Vigna mungo (L.) Hepper) is [...]

Prosopis represents a valuable forest resource in arid and semiarid regions. Management of promising species requires information about genetic parameters, mainly the heritability ([h.sup.2]) of quantitative profitable traits. This parameter is traditionally estimated from progeny tests or half-sib analysis conducted in experimental stands. Such an approach estimates [h.sup.2] from the ratio of between-family/total phenotypic variance. These analyses are difficult to apply to natural populations of species with a long life cycle, overlapping generations, and a mixed mating system, without genealogical information. A promising alternative is the use of molecular marker information to infer relatedness between individuals and to estimate [h.sup.2] from the regression of phenotypic similarity on inferred relatedness. In the current study we compared [h.sup.2] of 13 quantitative traits estimated by these two methods in an experimental stand of P. alba, where genealogical information was available. We inferred pairwise relatedness by Ritland's method using six microsatellite loci. Relatedness and heritability estimates from molecular information were highly correlated to the values obtained from genealogical data. Although Ritland's method yields lower [h.sup.2] estimates and tends to overestimate genetic correlations between traits, this approach is useful to predict the expected relative gain of different quantitative traits under selection without genealogical information. Key words: Fabaceae; heritability; Leguminosae; molecular markers; Prosopis alba; quantitative traits.

Tolerance to low P soils is a desirable trait in common bean (Phaseolus vulgaris L.) cultivars grown in acid-weathered soils. Genetic variability in response to P-deficient soils exists in the Andean gene pool. G19833, a low P-tolerant indeterminate Andean landrace, has been evaluated for quantitative trait loci (QTL) and tolerance to low P in combination with Mesoamerican parents. Our goal was to expand our understanding of phenotypic traits and QTL from G19833 expressed in an Andean background. An [F.sub.5:7] recombinant inbred line (RIL) population developed from two Andean bean genotypes, G19833 and AND696, a determinate line susceptible to low P soils, was examined under low and high soil P levels in replicated field trials. Phosphorus uptake was reduced by 70% and yield by 60% in low P compared to high P treatments. A linkage map was developed with 11 linkage groups and a total length of 1105 cM. Quantitative trait loci for root growth, seed yield, seed P content, and P use efficiency colocalized near the fin gene on linkage group B1. Quantitative trait loci for root growth traits, seed yield, and P uptake colocalized on B11. Quantitative trait loci for root length density (cm [cm.sup.-3]) and root surface area ([cm.sup.2]) did not colocalize with QTL for P uptake. This study indicates that root traits did not play an important role in tolerance to low P soil in an Andean x Andean cross, contrary to previous results with the same P-efficient Andean parent (G19833) crossed to a Mesoamerican bean genotype.

Abstract.--Knowledge of genetic variation and population structure is critically important in the conservation of endangered species. The level and partitioning of genetic variation in the narrow endemic Astragalus jaegerianus was [...]

Identification of forage legumes well adapted to the southeastern United States is complicated by climatic, soil, and biotic factors. Among the pests that impact forage legume persistence are root-knot nematodes (RKNs) (Meloidogyne spp.). We hypothesized that legumes native to the region should have higher levels of resistance to RKN species that are common in this region due to long-term natural selection pressure. The objective of this research was to evaluate the response of 10 southeastern U.S. native legumes to M. arenaria (Neal) Chitwood race 1, M. incognita (Kofoid and White) Chitwood race 3, and M. javanica (Treub) Chitwood. Legumes were grown in Cone-tainers in a greenhouse for 3 wk, inoculated with a given RKN isolate, and after an additional 9 wk were uprooted and evaluated for root galling and nematode egg mass production responses. The level of root galling and egg mass production varied among native legumes, but in general was lower than previously observed on introduced legumes. Desmodium paniculatum (L.) DC., Galactia regularis (L.) Britton et al., and Centrosema virginianum (L.) Benth. varied among the three RKN species in their root galling and egg mass production responses. The accession of D. incanum DC. used was immune to all three RKN isolates, and could be a potential source of RKN resistance genes. The perennial native legumes evaluated all had either a fleshy taproot or a strong rhizome system.

Seedling emergence time is a crucial event in the life cycle of a plant, determining its fitness via different components including survival, growth, and fecundity. Precocious emergents usually survive, grow, and/or reproduce earlier in the life cycle, but for perennials it is unknown whether these benefits are maintained throughout the life of the plant. Here, we examine for the first time whether fitness benefits due to the early emergence of perennial plants are perpetuated or vanish with time. For nine years, in a Mediterranean gorse community, we followed the fate of 2118 seedlings belonging to the four dominant woody species. We estimated phenotypic selection gradients on emergence time for three fitness components (survival, growth, and fecundity), under two experimentally simulated scenarios (fire and fire + erosion), at two different times in the life of the plant (3 and 9 years). Fire and erosion represent two potential selective forces constraining the temporal window of seedling emergence in Mediterranean habitats. All the species exhibited selection for early emergence, but through different fitness components. Directional selection favoring early emergence via survival in both fire scenarios was detected in the two Cistaceae species (Helianthemum marifolium and Cistus albidus), in which precocious emergents had higher fitness values late in the life cycle (9 years). In contrast, Fabaceae species (Ononis fruticosa and Ulex parviflorus) were not selected for early emergence via survival. Early emergents of all species in both fire scenarios had higher fitness values through growth early in the life cycle: these benefits decreased slightly with time but remained statistically significant, except in H. marifolium. Finally, late fecundity was enhanced by early emergence in both fire scenarios in C. albidus and U. parviflorus but not in H. marifolium. In conclusion, benefits acquired by emerging early are perpetuated for at least nine years. Key words: Cistaceae; early emergence; Fabaceae; plant fitness; seedling emergence; seedling fecundity; seedling growth; time of emergence.

Platymiscium is a neotropical legume genus of forest trees in the Pterocarpus clade of the pantropical 'dalbergioid' clade. It comprises 19 species (29 taxa), distributed from Mexico to southern Brazil. This study presents a molecular phylogenetic analysis of Platymiscium and allies inferred from nuclear ribosomal (nrITS) and plastid (trnL, trnL-F and matK) DNA sequence data using parsimony and Bayesian methods. Divergence times are estimated using a Bayesian method assuming a relaxed molecular clock (multidivtime). Within the Pterocarpus clade, new sister relationships are recovered: Pterocarpus + Etaballia, Inocarpus + Tipuana and Paramachaerium + Maraniona. Our results support monophyly of Platymiscium, which is resolved into three major clades, each with distinct geographic ranges and ecological preferences. Diversification in Platymiscium has been driven by habitat fragmentation, invasion of novel geographic regions, and ecological diversification, revealing general patterns of diversification in the neotropics. We hypothesize that Platymiscium arose in dry habitats of South America and radiated northward. The Amazon basin was invaded twice both within the last 5.6 My and Central America twice before the closure of the Isthmus of Panama. Divergence times of the P. pubescens complex, restricted to seasonally dry tropical forests of South America, support pre-Pleistocene divergence in this biome. Key words: biogeography; divergence times; Isthmus of Panama; Leguminosae; neotropics; phylogenetics; Platymiscium; Pterocarpus clade; seasonally dry tropical forests.

Expression of the Arabidopsis TRANSPARENT TESTA 2 (TT2) MYB family transcription factor leads to massive accumulation of proanthocyanidins (PAs) in hairy roots of Medicago truncatula. Microarray analysis showed that TT2 induces genes for flavonoid/PA biosynthesis, transcription factors, and a large number of genes of unknown function. A second microarray dataset identified genes that were preferentially expressed in the M. truncatula seed coat. Comparison of the two datasets defines target genes for steps that are yet unidentified in PA biosynthesis and accumulation. Of these genes, a glycosyltransferase, UGT72L1, was active specifically toward the PA precursor (-)--epicatechin, and its expression pattern in developing seeds correlated with the presence of epicatechin glucoside and accumulation of PA5. UGT72L1 may be involved in the production of epicatechin 3'-O-glucoside in the seed coat as a key step in PA biosynthesis or its regulation. glucosyltransferase | model legume | proanthocyanidin