Spatial patterns in phage-Rhizobium coevolutionary interactions across regions of common bean domestication

Bacteriophages play significant roles in the composition, diversity, and evolution of bacterial communities. Despite their importance, it remains unclear how phage diversity and phage-host interactions are spatially structured. Local adaptation may play a key role. Nitrogen-fixing symbiotic bacteria, known as rhizobia, have been shown to locally adapt to domesticated common bean at its Mesoamerican and Andean sites of origin. This may affect phage-rhizobium interactions. However, knowledge about the diversity and coevolution of phages with their respective Rhizobium populations is lacking. Here, through the study of four phage-Rhizobium communities in Mexico and Argentina, we show that both phage and host diversity is spatially structured. Cross-infection experiments demonstrated that phage infection rates were higher overall in sympatric rhizobia than in allopatric rhizobia except for one Argentinean community, indicating phage local adaptation and host maladaptation. Phage-host interactions were shaped by the genetic identity and geographic origin of both the phage and the host. The phages ranged from specialists to generalists, revealing a nested network of interactions. Our results suggest a key role of local adaptation to resident host bacterial communities in shaping the phage genetic and phenotypic composition, following a similar spatial pattern of diversity and coevolution to that in the host.Fil: Van Cauwenberghe, Jannick. University of California at Berkeley; Estados Unidos. Universidad Nacional Autónoma de México; MéxicoFil: Santamaría, Rosa I.. Universidad Nacional Autónoma de México; MéxicoFil: Bustos, Patricia. Universidad Nacional Autónoma de México; MéxicoFil: Juárez, Soledad. Universidad Nacional Autónoma de México; MéxicoFil: Ducci, Maria Antonella. Universidad Nacional de Salta; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Figueroa Fleming, Trinidad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina. Universidad Nacional de Salta; ArgentinaFil: Etcheverry, Angela Virginia. Universidad Nacional de Salta; ArgentinaFil: González, Víctor. Universidad Nacional Autónoma de México; Méxic

Anther-stigma separation in Desmodium species (Papilionoideae-Fabaceae) from northwestern Argentina

The repeated evolutionary transition from outcrossing to self-fertilization in angiosperms has been suggested to occur because selfing provides reproductive assurance. This transition is commonly associated with modifications of floral traits, among them herkogamy (the spatial separation between dehiscing anthers and the receptive stigma). Here, we investigate variation in levels of herkogamy in Desmodium incanum, D. pachyrrhizum, D. subsericeum and D. uncinatum, to determine the relationship between variation in this floral trait and self-pollen deposition. These species are self-compatible and bee-pollinated, with ornamental potential and may be used for forage given their high nutritional value. We studied natural populations located in Lerma Valley, Salta Province, Argentina. In January and February 2009, we marked and bagged 10 floral buds from 10 individual plants per species. The flowers were collected before their senescence; anther-stigma separation was measured immediately after collection with digital calipers (0.01 mm) as the distance between the surface of the stigma and the nearest anther. The stigmas were preserved in 70% ethanol. Pollen grains were counted under a microscope (10×) in the laboratory. There was significant variation in herkogamy levels among species. There was a negative correlation between anther-stigma distance and the number of self-pollen grains deposited on the stigma in isolated flowers. The variation in levels of herkogamy may represent a mechanism to ensure the production of some self-fertilized progeny in the absence of pollinators.Fil: Etcheverry, A. V.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Alemán, M. M.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Figueroa Fleming, Trinidad. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Gómez, C. A.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Lopez Spahr, Diego. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentin

Generalised pollination system of Erythrina dominguezii (Fabaceae:Papilionoideae) involving hummingbirds, passerines and bees

Plants in the genus Erythrina are pollinated by birds, such that passerine pollination is the plesiomorphic state, whereas hummingbird pollination is the derived character. Phylogenetic studies suggest that Erythrina dominguezii belongs to a basal clade characterised as pollinated by both passerines and hummingbirds. Here, we characterise the pollination system of E. dominguezii. Floral morphology, nectar traits, breeding system, visitation rates and pollen deposition by its floral visitors were studied. Floral morphology of E. dominguezii showed traits associated with both passerine and hummingbird pollination. Nectar sugar concentration showed an intermediate value but closer to the hummingbird type; however, it was rich in hexose, which is typical of the passerine type. Approximately 5% of the flowers set fruits under free pollination. Almost 80% of recorded flowers were visited by birds, with the rest visited by hymenopterans (bumblebees and honeybees). Among avian pollinators, five species of hummingbirds and three passerine species were identified as pollinators. The hummingbird Chlorostilbon lucidus was the most efficient visitor in terms of pollen deposition and was second in frequency of visits. The passerine Icterus cayanensis was second in efficiency at depositing pollen and was the most frequent pollinator. Our results show that E. dominguezii has a generalised pollination system. In addition, we report a new case of closed flowers and secondary nectar presentation. This is the first study that compares effectiveness among different pollinators in Erythrina. © 2012 CSIRO.Fil: Etcheverry, Angela Virginia. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; ArgentinaFil: Figueroa Castro, Dulce. Benemérita Universidad Autónoma de Puebla; MéxicoFil: Figueroa Fleming, Trinidad. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; ArgentinaFil: Aleman, Maria Mercedes. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; ArgentinaFil: Jaurez, Victor D.. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; ArgentinaFil: Lopez Spahr, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; ArgentinaFil: Yañez, Carolina Noemi. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; ArgentinaFil: Gómez, Carlos Anselmo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; Argentin

Pollen:ovule ratio and its relationship with other floral traits in Papilionoideae (Leguminosae): an evaluation with Argentine species

The pollen:ovule ratio (P ⁄ O) has traditionally been used as a rough estimator of plant breeding systems. It has been shown that plant breeding systems are associated with particular floral traits. In this study, we determined the P ⁄ O in 21 Leguminosae species from Argentina and explored relationships between P ⁄O and taxonomic position, flower size, floral rewards, pollen presentation and pollination mechanisms. According to the results, 15 out of the 21 species classified were obligate xenogamous, although some of them have been recorded as facultative xenogamous in previous studies. There was a significant effect of taxonomic position (genus), reward type and pollination mechanism on P ⁄O. Species offering only nectar as a floral reward (which were species with a brush mechanism) had a signifi- cantly lower P ⁄O than species offering pollen or pollen and nectar. Species with the brush pollination mechanism had the lowest P ⁄ O, while species with valvular and pump mechanism had the highest P ⁄O. However, pollen presentation (primary and secondary) and flower size did not have a significant effect on P ⁄ O. Our results demonstrate that P ⁄ O variability is determined by taxonomic position and pollination mechanism in this plant group.Fil: Etcheverry, A. V.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Alemán, M. M.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Figueroa Fleming, Trinidad. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lopez Spahr, Diego. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Carlos Anselmo. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Yañez, C.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Figueroa Castro, D. M.. Benemerita Universidad Autonoma de Puebla; MéxicoFil: Ortega Baes, Francisco Pablo. Universidad Nacional de Salta. Facultad de Cs.naturales. Escuela de Agronomia. Laboratorio de Investigaciones Botanicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin