Mycorrhizal fungi and ectomycorrhiza associated bacteria isolated from an industrial desert soil protect pine seedlings against Cd(II) impact

Abstract

Effects of mycorrhization with Amanita rubescens or Hebeloma sinapizans and dual inoculation with the fungi and ectomycorrhiza associated bacteria (EMAB) Pseudomonas putida or Bacillus cereus on seedling growth and accumulation of Cd(II) in Pinus sylvestris were studied. Both fungal and bacterial species were isolated from roots of pines growing in an industrial area polluted with high concentrations of heavy metals. During mycorrhization, A. rubescens colonized higher number of pine seedlings than H. sinapizans, especially when EMAB were co-inoculated. In addition, the seedling biometric characteristics (i.e. root and shoot lengths and biomass) were stimulated by treatment with the fungal species alone and dual inoculation with the fungi and EMAB. Amanita rubescens was more efficient in this stimulation than H. sinapizans. The increased growth of pine seedlings was especially seen for co-inoculation with P. putida. Furthermore, elevated accumulation of Cd(II), ranging from 56 microg g(-1) to 72 microg g(-1) dry weight, in underground parts of the inoculated seedlings was found. The seedlings treated with A. rubescens accumulated higher concentrations of the metal than those inoculated with H. sinapizans. Additional treatment of pine seedlings with P. putida resulted in the higher accumulation of Cd(II) in the roots as compared with those inoculated with B. cereus. The results suggest that the growth of pine seedlings in Cd(II)-polluted soil may depend on fungal species forming ectomycorrhizae, species-specific co-inoculation with EMAB and specificity of fungal-EMAB interactions.

Evaluación de la inoculación con microorganismos fijadores de nitrógeno asimbióticos aislados de la rizósfera de Pinus patula en Colombia

“…Por otro lado, se ha encontrado que las asociaciones tripartitas (hongo ectomicorrízico-bacterias asociadas-especie forestal) han resultado beneficiosas en suelos contaminados con metales pesados, ya que estudios recientes han demostrado que la colonización de plántulas del pino albar (Pinus sylvestris L.) con hongos ectomicorrízicos específicos y bacterias asociadas a éstos provee protección a la especie forestal contra el efecto de ciertos metales pesados como zinc, cadmio y plomo, siendo promisorio su uso para el establecimiento de plantaciones de coníferas en suelos contaminados con estos metales (Kozdrój et al 2007).…”

“…Sin embargo, es importante resaltar que la colonización bacterial de las ectomicorrizas muestra cierta especificidad entre el hospedero y el simbionte, pudiendo influenciar positiva o negativamente en la micorrización y por ende en el crecimiento de las plantas (Garbaye 1994, Poole et al 2001. Esta especificidad posiblemente está dada por el efecto combinado del tipo de suelo, el simbionte fúngico, la planta hospedero y la localización de las comunidades asociadas con las ectomicorrizas del árbol (Timonen et al 1999, Kozdrój et al 2007, haciendo entendible por qué no todas las bacterias inoculadas en P. patula colonizaron la raíz micorrizada o los diferentes niveles de micorrización encontrados. Por otro lado, Shishido et al (1996) encontraron que diferentes especies de Bacillus incrementan el crecimiento longitudinal de las coníferas por mecanismos diferentes a la micorrización.…”

Adaptation of Selected Ectomycorrhizal Fungi to Increased Concentration of Cadmium and Lead

“…From all research stations healthy fruiting bodies with dimensions of 10-14 cm in height and approx 5 cm cap diameter were harvested and pure cultures of mycelium were derived in accordance to tissue method developed by Pachlewski and modified by Kozdroj [11] what involves cutting in sterile condition sections of plectenchyma from the centre of the cap of approx. 0.5 cm width, length and thickness.…”

“…This is well documented in wooden plants that go into the mutualistic mycorrhizal symbiosis and produce ectomycorrizal roots which preserve, store and exchange mineral salts and water [9]. It has been shown that this type of plant association with fungi significantly enhance their tolerance to toxic concentration of heavy metals in soil [10][11][12][13].…”

Transcriptome analysis by cDNA-AFLP of Suillus luteus Cd-tolerant and Cd-sensitive isolates

“…Pines inoculated with Laccaria bicolor while exposed to Cd grew better than non-mycorrhizal plants and maintained a higher nutrient status (Ahonen-Jonnarth and Finlay 2001), an effect that might be further strengthened by ectomycorrhiza associated bacteria (Kozdroj et al 2007). The beneficial effect induced by the fungus is nevertheless species and isolate specific.…”