Enhancement of clover growth by inoculation of P-solubilizing fungi and arbuscular mycorrhizal fungi

This study evaluated the synergism between several P-solubilizing fungi isolates and arbuscular mycorrhizal fungi to improve clover ( Trifolium pratense) growth in the presence of Araxá apatite. Clover was sown directly in plastic pots with 300g of sterilized washed sand, vermiculite and sepiolite 1:1:1 (v:v:v) as substrate, and grown in a controlled environment chamber. The substrate was fertilized with 3 g L-1 of Araxá apatite. A completely randomized design, in 8×2 factorial scheme (eight P-solubilizing fungi treatments with or without arbuscular mycorrhizal fungi)and four replicates were used. The P-solubilizing fungi treatments consisted of five Brazilian P-solubilizing fungi isolates (PSF 7, 9, 20, 21 and 22), two Spanish isolates ( Aspergillus niger and the yeast Yarowia lipolytica) and control (non-inoculated treatment). The greatest clover growth rate was recorded when Aspergillus niger and PSF 21 were co-inoculated with arbuscular mycorrhizal fungi. Aspergillus niger, PSF 7 and PSF 21 were the most effective isolates on increasing clover growth in the presence of arbuscular mycorrhizal fungi. Greater mycorrhizal colonization resulted in greater clover growth rate in most PSF treatments. PSF 7 was the best isolate to improve the establishment of mycorrhizal and rhizobia symbiosis.Este estudo avaliou o sinergismo entre diversos isolados defungos solubilizadores de fosfato e micorrízicos arbusculares para beneficiar o crescimento de trevo ( Trifolium pratense) na presença de apatita de Araxá. A cultura foi semeada diretamente em potes plásticos com 300 g de substrato esterilizado formado por areia lavada, vermiculita e sepiolita 1:1:1 (v:v:v) e cultivada em câmara climática. O substrato foi fertilizado com 3 g L-1 de apatita de Araxá. O experimento foi instalado em delineamento completamente casualizado, esquema fatorial 8×2 (oito tratamentos de inoculação de fungos solubilizadores de fosfato com ou sem fungos micorrízicos arbusculares) e quatro repetições. Os tratamentos de fungos solubilizadores de fosfato consistiram em cinco isolados brasileiros de fungos solubilizadores de fosfato (FSF 7, 9, 20, 21 e 22), dois isolados procedentes da Espanha ( Aspergillus niger e a levedura Yarowia lipolytica) e o controle (tratamento não inoculado). A maior taxa de crescimento da cultura foi obtida quando Aspergillus niger e FSF 21 foram co-inoculados com fungos micorrízicos arbusculares. Aspergillus niger, FSF 7 e o FSF 21 foram os isolados mais efetivos para incrementar o crescimento de trevo na presença de fungos micorrízicosarbusculares. A maior taxa de colonização micorrízica resultou em alta taxa de crescimento de trevo na maioria dos tratamentos com fungos solubilizadores de fosfato. O isolado FSF 7 foi o melhor para favorecer o estabelecimento das simbioses com fungos micorrízicos e com rizóbio

Laying the Foundations for a Human-Predator Conflict Solution: Assessing the Impact of Bonelli's Eagle on Rabbits and Partridges

BACKGROUND: Predation may potentially lead to negative effects on both prey (directly via predators) and predators (indirectly via human persecution). Predation pressure studies are, therefore, of major interest in the fields of theoretical knowledge and conservation of prey or predator species, with wide ramifications and profound implications in human-wildlife conflicts. However, detailed works on this issue in highly valuable--in conservation terms--Mediterranean ecosystems are virtually absent. This paper explores the predator-hunting conflict by examining a paradigmatic, Mediterranean-wide (endangered) predator-two prey (small game) system. METHODOLOGY/PRINCIPAL FINDINGS: We estimated the predation impact ('kill rate' and 'predation rate', i.e., number of prey and proportion of the prey population eaten, respectively) of Bonelli's eagle Aquila fasciata on rabbit Oryctolagus cuniculus and red-legged partridge Alectoris rufa populations in two seasons (the eagle's breeding and non-breeding periods, 100 days each) in SE Spain. The mean estimated kill rate by the seven eagle reproductive units in the study area was c. 304 rabbits and c. 262 partridges in the breeding season, and c. 237 rabbits and c. 121 partridges in the non-breeding period. This resulted in very low predation rates (range: 0.3-2.5%) for both prey and seasons. CONCLUSIONS/SIGNIFICANCE: The potential role of Bonelli's eagles as a limiting factor for rabbits and partridges at the population scale was very poor. The conflict between game profitability and conservation interest of either prey or predators is apparently very localised, and eagles, quarry species and game interests seem compatible in most of the study area. Currently, both the persecution and negative perception of Bonelli's eagle (the 'partridge-eating eagle' in Spanish) have a null theoretical basis in most of this area

Arbuscular mycorrhizal inoculation enhances plant growth and changes root system morphology in micropropagated Annona cherimola Mill

The effect of arbuscular mycorrhizal formation on plant development and root system morphogenesis in micropropagated Annona cherimola plants was investigated. A juvenile rootstock was used and already rooted in vitro plantlets were inoculated with arbuscular mycorrhizal propagules at the beginning of their acclimatization phase. Mycorrhization improved plant development (root, steam and leaves), but decreased the specific root length. Arbuscular mycorrhizal formation did not change the degree of branching nor the lateral root frequency for the adventitious roots, but significantly increased the intensity of branching of the first-order laterals. These results corroborate the role of arbuscular mycorrhizal symbiosis inducing beneficial changes in root system morphology and in the general developmental pattern in micropropagated plants.L'inoculation de mycorhizes arbusculaires augmente la croissance de la plante et change la morphologie du système racinaire d'Annona cherimola Mill micropropagés. L'effet de la formation de mycorhizes arbusculaires sur le développement de la plante et la morphogenèse du système racinaire d'Annona cherimola a été étudié. Un porte-greffe juvénile a été utilisé et des plantes déjà enracinées in vitro ont été inoculées avec des propagules de mycorhizes arbusculaires au début de la période d'acclimatation. La mycorhization améliore le développement de la plante (racines, tiges, feuilles) mais diminue la longueur spécifique des racines. La formation de mycorhizes arbusculaires ne change pas pour les racines adventives, ni le degré d'embranchement, ni la fréquence des racines latérales, mais augmente sensiblement l'intensité des branchements des racines de premier ordre. Ces résultats corroborent le rôle de la symbiose mycorhizienne dans l'induction de changements bénéfiques au niveau de la morphologie du système racinaire et en général du développement de plants micropropagés

Induction of new chitinase isoforms in tomato roots during interactions with Glomus mosseae and/or Phytophthora nicotianae var parasitica

Les activités chitinases de racines de tomate en symbiose avec le champignon mycorhizogène Glomus mosseae, dans une interaction pathogène avec Phytophthora nicotianae var parasitica et dans des racines colonisées par G mosseae depuis deux semaines et post-infectées par le pathogène ont été étudiées en gels d'électrophorèse natifs (Page) et dénaturants (SDS-Page). En conditions natives, les racines témoins ont révélé plusieurs isoformes acides de chitinase. Une isoforme additionnelle a été détectée dans les racines colonisées par G mosseae, tandis qu'une isoforme additionnelle différente et une plus forte expression des isoformes constitutives ont été observées dans les racines infectées par le pathogène. Quand les racines étaient mycorhizées puis infectées par le pathogène, l'ensemble des isoformes induites par les deux champignons a été détecté. Sur les quatre isoformes basiques présentes dans tous les extraits, seules les activités des racines infectées par le pathogène étaient stimulées. Après dénaturation en conditions non réductrices, les isoformes de chitinase des racines mycorhizées se sont renaturées plus rapidement et plus facilement que celles des racines non mycorhizées et cela même lorsque les plantes mycorhizées ont été ultérieurement infectées par le pathogène

Belowground mutualists and the invasive ability of Acacia longifolia in coastal dunes of Portugal

The ability to form symbiotic associations with soil microorganisms and the consequences for plant growth were studied for three woody legumes grown in five different soils of a Portuguese coastal dune system. Seedlings of the invasive Acacia longifolia and the natives Ulex europaeus and Cytisus grandiflorus were planted in the five soil types in which at least one of these species appear in the studied coastal dune system. We found significant differences between the three woody legumes in the number of nodules produced, final plant biomass and shoot 15N content. The number of nodules produced by A. longifolia was more than five times higher than the number of nodules produced by the native legumes. The obtained 15N values suggest that both A. longifolia and U. europaeus incorporated more biologically-fixed nitrogen than C. grandiflorus which is also the species with the smallest distribution. Finally, differences were also found between the three species in the allocation of biomass in the different studied soils. Acacia longifolia displayed a lower phenotypic plasticity than the two native legumes which resulted in a greater allocation to aboveground biomass in the soils with lower nutrient content. We conclude that the invasive success of A. longifolia in the studied coastal sand dune system is correlated to its capacity to nodulate profusely and to use the biologically-fixed nitrogen to enhance aboveground growth in soils with low N content