Dynamics of Fungal Communities in Bulk and Maize Rhizosphere Soil in the Tropics

Abstract

The fungal population dynamics in soil and in the rhizospheres of two maize cultivars grown in tropical soils were studied by a cultivation-independent analysis of directly extracted DNA to provide baseline data. Soil and rhizosphere samples were taken from six plots 20, 40, and 90 days after planting in two consecutive years. A 1.65-kb fragment of the 18S ribosomal DNA (rDNA) amplified from the total community DNA was analyzed by denaturing gradient gel electrophoresis (DGGE) and by cloning and sequencing. A rhizosphere effect was observed for fungal populations at all stages of plant development. In addition, pronounced changes in the composition of fungal communities during plant growth development were found by DGGE. Similar types of fingerprints were observed in two consecutive growth periods. No major differences were detected in the fungal patterns of the two cultivars. Direct cloning of 18S rDNA fragments amplified from soil or rhizosphere DNA resulted in 75 clones matching 12 dominant DGGE bands. The clones were characterized by their HinfI restriction patterns, and 39 different clones representing each group of restriction patterns were sequenced. The cloning and sequencing approach provided information on the phylogeny of dominant amplifiable fungal populations and allowed us to determine a number of fungal phylotypes that contribute to each of the dominant DGGE bands. Based on the sequence similarity of the 18S rDNA fragment with existing fungal isolates in the database, it was shown that the rhizospheres of young maize plants seemed to select the Ascomycetes order Pleosporales, while different members of the Ascomycetes and basidiomycetic yeast were detected in the rhizospheres of senescent maize plants.

Phylogenic diversity and tissue specificity of fungal endophytes associated with the pharmaceutical plant, Stellera chamaejasme L. revealed by a cultivation-independent approach

“…Nevertheless, S. chamaejasme is a perennial plant, the roots have more time and opportunities to be inhabited by various fungi than the above-ground parts. The high proportion of Pleosporales, Hypocreales, Eurotiales or Diaporthales detected indicates that these orders as main components of the rhizospheric and endophytic mycota of many plants (Keim et al 2014;Marcial Gomes et al 2003;Rivera-Orduña et al 2011;Unterseher et al 2013). However, dissimilar result is also found in the other study on fungal endophyte communities of the Indian medicinal plant Tinospora cordifolia.…”

The Abundance and Diversity of Soil Fungi in Continuously Monocropped Chrysanthemum

“…Furthermore, the plant development stage also influenced fungi diversity significantly, a result which is inconsistent with the claim that the plant only has a minor influence on the constitution of the rhizosphere fungal community [20, 41]. The reason for this inconsistency was likely that the different soil types and sampling methods lead to the different results.…”

Molecular mechanisms of canalization: Hsp90 and beyond

“…For example, further empirical studies will have to address the proposed role and importance of Hsp90 in epigenetic processes (Zhao et al 2005), which could possibly expand our current view of Hsp90 as a chaperone of mostly cytoplasmic proteins. Similarly, the existence and abundance of highly specifi c Hsp90 inhibitors in nature (Gomes et al 2003;Turbyville et al 2006), beckons the systematic exploration of Hsp90 as an interface between organisms with possibly wide-ranging ecological implications.…”

“…In addition to facilitating defense against pathogens, Hsp90 plays a pivotal role in other classic plastic responses such as light perception, seedling etiolation, and gravitropism (Cao et al 2000;Queitsch et al 2002;Hubert et al 2003). Moreover, recent studies report the production of highly specifi c Hsp90 inhibitors by fungi living in rhizospheres of diverse plant species, establishing Hsp90 as a potential target in interactions between organisms (Gomes et al 2003;Turbyville et al 2006).…”