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( Constanza Marini-macouzet ),( Luis Muñoz ),( Aldo Gonzalez-rubio ),( Luis E. Eguiarte ),( Valeria Souza ),( Patricia Velez ) 한국균학회 2020 Mycobiology Vol.48 No.5
Fungal ecological interactions play a key role in structuring community assemblages. These associations may involve both antagonistic and synergistic relationships, which are commonly influenced by abiotic factors such as nutrient conditions. However, information for extreme, oligotrophic systems remain poor. Herein, interactions among key members of the aquatic transient fungal community (Aspergillus niger, Cladosporium sp., and Coprinellus micaceus) of a low-nutrient freshwater system in the Cuatro Ci_enegas Basin, Mexico were studied. Pairwise interaction bioassays were explored in vitro under different nutrient conditions, including carbohydrates-rich, carbohydrates and amino peptides-rich, and low nutrients. Our results indicated that antagonistic patterns prevail among the studied taxa. However, nutrient- dependent changes were observed in Cladosporium sp. shifting to synergy under carbohydrates- rich conditions, suggesting changes in the fungal community composition as a result of nutrient enrichment. Remarkably, our findings contrast with previous work demonstrating mainly synergistic interactions between our tested fungal isolates and co-occurring autochthonous bacteria (Aeromonas spp. and Vibrio sp.) under low-nutrient conditions. This observation may indicate that bacteria and fungi exhibit distinct community-level responses, driven by nutrient conditions. This contributes to the knowledge of fungal community dynamics and interspecific interactions in an oligotrophic ecosystem, highlighting the relevance of nutrient-based shifts and antagonistic interactions in ecosystem dynamics.
Sanderson, Michael J.,Copetti, Dario,Bú,rquez, Alberto,Bustamante, Enriquena,Charboneau, Joseph L. M.,Eguiarte, Luis E.,Kumar, Sudhir,Lee, Hyun Oh,Lee, Junki,McMahon, Michelle,Steele, Kelly,Wing Botanical Society of America, Inc. (Columbus) * Bu 2015 American journal of botany Vol. No.
<P>• <I>Premise of the study:</I> Land-plant plastid genomes have only rarely undergone significant changes in gene content and order. Thus, discovery of additional examples adds power to tests for causes of such genome-scale structural changes.</P><P>• <I>Methods:</I> Using next-generation sequence data, we assembled the plastid genome of saguaro cactus and probed the nuclear genome for transferred plastid genes and functionally related nuclear genes. We combined these results with available data across Cactaceae and seed plants more broadly to infer the history of gene loss and to assess the strength of phylogenetic association between gene loss and loss of the inverted repeat (IR).</P><P>• <I>Key results:</I> The saguaro plastid genome is the smallest known for an obligately photosynthetic angiosperm (∼113 kb), having lost the IR and plastid <I>ndh</I> genes. This loss supports a statistically strong association across seed plants between the loss of <I>ndh</I> genes and the loss of the IR. Many nonplastid copies of plastid <I>ndh</I> genes were found in the nuclear genome, but none had intact reading frames; nor did three related nuclear-encoded subunits. However, nuclear <I>pgr5</I>, which functions in a partially redundant pathway, was intact.</P><P>• <I>Conclusions:</I> The existence of an alternative pathway redundant with the function of the plastid NADH dehydrogenase-like complex (NDH) complex may permit loss of the plastid <I>ndh</I> gene suite in photoautotrophs like saguaro. Loss of these genes may be a recurring mechanism for overall plastid genome size reduction, especially in combination with loss of the IR.</P>