Expression analysis of Clavata1-like and Nodulin21-like genes from Pinus sylvestris during ectomycorrhiza formation

The ecology and physiology of ectomycorrhizal (EcM) symbiosis with conifer trees are well documented. In comparison, however, very little is known about the molecular regulation of these associations. In an earlier study, we identified three EcM-regulated Pinus expressed sequence tags (EST), two of which were identified as homologous to the Medicago truncatula nodulin MtN21. The third EST was a homologue to the receptor-like kinase Clavata1. We have characterized the expression patterns of these genes and of auxin- and mycorrhiza-regulated genes after induction with indole-3-butyric acid in Pinus sylvestris and in a time course experiment during ectomycorrhizal initiation with the co-inoculation of 2,3,5-triiodobenzoic acid, an auxin transport inhibitor. Our results suggest that different P. sylvestris nodulin homologues are associated with diverse processes in the root. The results also suggest a potential role of the Clv1-like gene in lateral root initiation by the ectomycorrhizal fungus

Soil enzyme activities, microbial community composition and function after 47 years of continuous green manuring

Green manuring practices can influence soil microbial community composition and function and there is a need to investigate the influence compared with other types of organic amendment. This study reports long-term effects of green manure amendments on soil microbial properties, based on a field experiment started in 1956. In the experiment, various organic amendments, including green manure, have been applied at a rate of 4 t C ha(-1) every second year. Phospholipid fatty acid analysis (PLFA) indicated that the biomass of bacteria, fungi and total microbial biomass, but not arbuscular mycorrhizal (AM) fungi, generally increased due to green manuring compared with soils receiving no organic amendments. Some differences in abundance of different microbial groups were also found compared with other organic amendments (farmyard manure and sawdust) such as a higher fungal biomass and consequently a higher fungal/bacterial ratio compared with amendment with farmyard manure. The microbial community composition (PLFA profile) in the green manure treatment differed from the other treatments, but there was no effect on microbial substrate-utilization potential, determined using the Biolog EcoPlate. Protease and arylsulphatase activities in the green manure treatment were comparable to a mineral fertilized treatment receiving no additional C, whereas acid phosphatase activity increased. It can be concluded that green manuring had a beneficial impact on soil microbial properties, but differed in some aspects to other organic amendments which might be attributed to differences in quality of the amendments

Efectos maternos en Pinus pinaster en relación a mecanismos de defensa

1 página.- Resumen de la comunicación oral presentada en la Reunión celebrada en la ETSI Montes, Forestal y del Medio Natural de la Universidad Politécnica de Madrid, los días 7 y 8 de octubre de 2015.Adaptar la progenie a las condiciones prevalentes del ambiente materno podría ser especialmente beneficioso para organismos estacionarios y longevos, y con una capacidad limitada de dispersión de semilla como las coníferas. La adaptación mediante cambios genéticos (la re-organización cromosómica, mutaciones, inserciones o deleciones) es esperable que sea lenta dada la baja frecuencia con la que ocurren estos eventos de una generación a la siguiente. Un mecanismo adicional para aumentar la aptitud de la progenie es la llamada memoria epigenética, que sin alterar el ADN, es capaz de influenciar el fenotipo de la siguiente generación. En este estudio hemos utilizado PCR cuantitativa para comparar la expresión basal e inducida por la señalización del daño por herbivoría de diferentes genes candidato en progenies de Pinus pinaster provenientes de diferentes ambientes maternos. Arboles madre clonados de tres genotipos fueron sometidos a heridas mecánicas (MW), a metil jasmonato (MJ) o dejados sin tratar durante el desarrollo de las semillas (control). Hemos observado indicios de efectos maternos en diferentes rutas metabólicas y procesos biológicos. La progenie proveniente del ambiente MJ muestra signos de tener activos los mecanismos de defensa de manera constitutiva, alcanzando una respuesta mayor a la del ambiente control 3 y 6 horas post-tratamiento. En cambio, la progenie del ambiente MW no se diferencia del ambiente control a nivel constitutivo, pero si alcanzan niveles de respuesta al tratamiento similares a los del ambiente MJ, sugiriendo un efecto de ‘priming’ transgeneracional sobre dichas rutas. Hemos comprobado que el genotipo influencia la respuesta a efectos maternos, especialmente en genes involucrados con el control epigenético. Actualmente estamos complementando los estudios de expresión génica con estudios de metilación en los genes candidatos con mayor respuesta, así como del estudio de todo el transcriptoma mediante RNA-seq.Peer reviewe

Comparative proteomic analysis of hyphae and germinating cysts of Phytophthora pisi and Phytophthora sojae.

The recently described oomycete pathogen Phytophthora pisi causes root rot on pea and faba bean, while the closely related Phytophthora sojae is the causal agent of soybean root and stem rot. Differences in the pathogenicity factor repertoires that enable the two species to have distinct host specificity towards pea and soybean, were studied using tandem mass spectrometry in a global proteome study of hyphae and germinating cysts in P. pisi and P. sojae. In total 2775 proteins from P. pisi and 2891 proteins from P. sojae were identified. Fifty-eight orthologous proteins were more abundant in germinated cysts of both pathogens and thus identified as candidate proteins for the infective stage. Several of these proteins were associated with lipid transport and metabolism, and energy production. Twenty-three orthologous proteins were more abundant in hyphae of both pathogens and thus identified as candidate proteins for vegetative growth. Proteins uniquely present in germinating cysts of either P. pisi or P. sojae were considered as candidates for species-specific pathogenicity factors that may be involved in host specificity. Among these proteins were serine proteases, membrane transporters and a berberine-like protein. These results significantly expand the knowledge of the expressed proteome in P. pisi and P. sojae