Lathyrus

About: Lathyrus is a research topic. Over the lifetime, 1130 publications have been published within this topic receiving 18126 citations.

Fitness effects of two facultative endosymbiotic bacteria on the pea aphid, Acyrthosiphon pisum, and the blue alfalfa aphid, A. kondoi

Abstract: The effects of two bacterial endosymbionts, designated PASS and PAR, were evaluated on the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera:Aphididae), in which they occur facultatively, and on the blue alfalfa aphid, A. kondoi Shinji, in which these bacteria have not been found in natural populations. Subclones of pea aphids and blue alfalfa aphids, derived from parent aphid clones that did not contain PASS or PAR, were infected with one or both bacteria, generating PASS- and/or PAR-positive subclones with minimal genetic differences from the parent clones. Under laboratory conditions at 20 °C, PAR consistently reduced the fecundity (by between 19 and 60%) of subclones derived from three different parent pea aphid clones on bur clover, Medicago hispida Gaertn. PAR had intermediate effects on pea aphids reared on sweet pea, Lathyrus odoratus L., and had no significant effect on pea aphids on alfalfa, Medicago sativa L. The effect of PASS was either neutral or negative, depending on parent clone as well as host plant. Also at 20 °C, PASS reduced fecundity (70–77%) and longevity (40–48%), and increased the age of first reproduction (by up to 1.5 days) of blue alfalfa aphid reared on alfalfa and clover. PAR had a less dramatic effect (e.g., 30–39% reduction in fecundity) on these traits of blue alfalfa aphid. In contrast, PAR and PASS increased the fitness of pea aphid subclones of one parent clone reared for three generations at 25 °C on each of the three test plants. Without facultative bacteria, fecundity of the parent clone was reduced to a mean total of 35. However, this ameliorative effect of facultative bacteria at 25 °C was not found for two other sets of parent clones and their derived subclones. Alate production in pea aphids was significantly increased in large populations of two PASS- and PAR-positive subclones relative to their parent clones. Attempts to transmit PASS or PAR horizontally, i.e., from aphid to aphid via feeding on host plants (bur clover), were unsuccessful.

Adaptation and seed yield of cool season grain legumes in mediterranean environments of south-western australia

Abstract: A range of cool season grain legume species have shown considerable potential for soils unsuitable for the production of narrow-leafed lupin (Lupinus angustifolius L.) at limited sites in the Mediterranean-type envi- ronments of south-western Australia. In this study the adaptation of these grain legume species was compared by measuring crop phenology, growth, and yield in field experiments at a total of 36 sites over 3 seasons, with the aim of identifying species with suitable adaptation and seed yield for specific environments. The grain legumes examined appeared to fall into 3 categories: (i) field pea (Pisum sativum L.), faba bean (Vicia faba L.), common vetch (Vicia sativa L.), and narbon bean (Vicia narbonensis L.) clearly had superior seed yield to the other species over a wide number of sites and years across south-western Australia (mean 1.0n2.3 t/ha); (ii) albus lupin (Lupinus albus L.), desi chickpea (Cicer arietinum L.), and Lathyrus cicera, L. sativus, and L. ochrus produced seed yields of 1n1.3 t/ha; and (iii) red lentil (Lens culinaris L.), bitter vetch (Vicia ervilia), and kabuli chickpea (Cicer arietinum L.) generally produced the lowest yields (0.6n1.0 t/ha). There were clear species · environment interactions. At low-yielding sites ( 6.0 and clay contents >15%. Seed yields were positively correlated with dry matter production at maturity across a number of sites (r 2 = 0.40, P < 0.01). Future improve- ments in seed yield of these species are likely to come from management practices that increase dry matter pro- duction such as increased plant density and early sowing, and through the development of genotypes with greater tolerance to low winter temperatures, and more rapid phenology, canopy development, and dry matter production than existing commercial cultivars.

Population genetic structure and secondary symbionts in host-associated populations of the pea aphid complex.

Abstract: Polyphagous insect herbivores experience different selection pressures on their various host plant species. How this affects population divergence and speciation may be influenced by the bacterial endosymbionts that many harbor. Here, we study the population structure and symbiont community of the pea aphid (Acyrthosiphon pisum), which feeds on a range of legume species and is known to form genetically differentiated host-adapted populations. Aphids were collected from eight legume genera in England and Germany. Extensive host plant associated differentiation was observed with this collection of pea aphids comprising nine genetic clusters, each of which could be associated with a specific food plant. Compared to host plant, geography contributed little to genetic differentiation. The genetic clusters were differentiated to varying degrees, but this did not correlate with their degree of divergence in host use. We surveyed the pea aphid clones for the presence of six facultative (secondary) bacterial endosymbionts and found they were nonrandomly distributed across the aphid genetic clusters and this distribution was similar in the two countries. Aphid clones on average carried 1.4 species of secondary symbiont with those associated with Lathyrus having significantly fewer. The results are interpreted in the light of the evolution of specialization and ecological speciation.

Localized hypermutation and associated gene losses in legume chloroplast genomes

Abstract: Point mutations result from errors made during DNA replication or repair, so they are usually expected to be homogeneous across all regions of a genome. However, we have found a region of chloroplast DNA in plants related to sweetpea (Lathyrus)whoselocalpointmutationrateisatleast20timeshigherthanelsewhereinthesamemolecule.Thereareveryfew precedents for such heterogeneity in any genome, and we suspect that the hypermutable region may be subject to an unusual process such as repeated DNA breakage and repair. The region is 1.5 kb long and coincides with a gene, ycf4, whose rate of evolution has increased dramatically. The product of ycf4, a photosystem I assembly protein, is more divergent within the single genus Lathyrus than between cyanobacteria and other angiosperms. Moreover, ycf4 has been lost from the chloroplast genome in Lathyrus odoratus and separately in three other groups of legumes. Each of the four consecutive genes ycf4-psaI-accD-rps16 has been lost in at least one member of the legume ‘‘inverted repeat loss’’ clade, despite the rarity of chloroplast gene losses in angiosperms. We established that accD has relocated to the nucleus in Trifolium species, but were unable to find nuclear copies of ycf4 or psaI in Lathyrus. Our results suggest that, as well as accelerating sequence evolution, localized hypermutation has contributed to the phenomenon of gene loss or relocation to the nucleus. [Supplemental material is available online at http://www.genome.org. The sequence data from this study have been submitted to GenBank (http://www.ncbi.nlm.nih.gov/Genbank/) under accession nos. HM029359–HM029371, HM048906– HM048910, and GO313838–GO322539.]