Interactions between callus cultures of Pinus sylvestris and pine fungi with different trophic properties

Abstract

Fungal virulence may be studied using tissues cultures of host plants in dual cultures in vitro, enabling analyses of interactions with undifferentiated cells of their host plants. Three genotypes of Pinus sylvestris callus, initiated by somatic embryogenesis, were used for establishing dual cultures with fungi pathogenic, endophytic or saprotrophic on pine needles or shoots. Fungal growth towards the plant callus tissue differed, depending on the life strategy of the fungus. The pathogen Gremmeniella abietina proved the slowest colonizer of callus whereas the saprotrophic Phacidium lacerum was the fastest. Gremmeniella abietina partially overgrew the callus, causing extensive necrosis and death within 10 days after inoculation. Anthostomella formosa, an endophyte of pines, did not cause evident symptoms of callus degradation: after 10 days of dual culture, the callus cells remained greenish and at least 50% of cells were alive. In dual cultures Ph. lacerum, callus remained alive until the end of the experiment, maintaining a white-creamy colour with a loose cell structure. Electrophoresis of protein extracts from the callus showed the presence of additional bands of 25-35 kDa only in host tissues challenged with the pathogen G. abietina, possibly indicating the production of pathogenesis-related proteins. This work has shown that pine callus does not respond equally to challenge with different fungal isolates. In general, one-third of the isolates of each fungus examined showed greater virulence compared to other isolates.

Effect of elicitors on holm oak somatic embryo development and efficacy inducing tolerance to Phytophthora cinnamomi

“…Chong et al 42 suggested that damages in cell membranes during the first days after elicitation of Morinda elliptica cell cultures with MeJA would trigger the biosynthesis of antioxidant enzymes, therefore inducing a subsequent decrease in MDA. Experiments using dual cultures have shown that the stimulation or inhibition of mycelium growth in these conditions could give useful information about plant susceptibility [43][44][45] , and therefore could be used to select efficient elicitation treatments 36,42 . In our study, elicited holm oak somatic embryos did not inhibit Phytophthora cinnamomi mycelium growth in dual culture tests, being the plates with somatic embryos elicited with PFE-50, 50 µM BTH, 5, 10 or 50 µM MeJA and 5 µM PABA those showing ratios higher than 1 between growth towards control and growth towards elicited material at the end of the experiment.…”

De novo Transcriptome Assembly of Phomopsis liquidambari Provides Insights into Genes Associated with Different Lifestyles in Rice (Oryza sativa L.)

“…When host plants are used as vectors for transcriptome level research, a small number of expressed endophyte genes are typically disregarded due to the significant background of plant genes (Porras-Alfaro and Bayman, 2011 ). The callus is an undifferentiated living cell structure of plants that contains a set of defense systems similar to host plants (Nawrot-Chorabik et al, 2016 ). In this study, we used dual cultures of rice callus and P. liquidambari to simulate an endophytic environment in which organisms can release signals to recognize each other and form a relationship of simulated antagonism balance.…”

“…The endophytic lifestyle was studied using tissues cultures of host rice in dual culture in vitro based on previous research (Sieber et al, 1990 ; Peters and Schulz, 1998 ; Nawrot-Chorabik et al, 2016 ). Inoculated rice seeds at the surface were sterilized in callus solid medium (1 × NB solid medium, 2 mg L −1 2,4-D, 30 g L −1 sucrose, 10 g L −1 agar, pH 7) and cultivated for 20 days at 28°C.…”

Novel Avenues for Plant Protection: Plant Propagation by Somatic Embryogenesis Enhances Resistance to Insect Feeding

“…The documented responses involving secondary compound production during the SE process suggest that interactions of SE-plants with biotic stresses could be affected. For instance, studies of host-pathogen interactions in early tissue development have shown that fungal mycelial growth is strongly reduced by inhibitory substances released by somatic embryos when grown together in culture ( Terho et al, 2000 ; Vookova et al, 2006 ; Hrib et al, 2013 ; Nawrot-Chorabik et al, 2016 ). Furthermore, changes in secondary compounds early in development may be persistent, as shown by plants propagated by SE to obtain compounds of medicinal interest.…”