Effect of karst rocky desertification on soil fungal communities in Southwest China.

Karst mountainous ecosystems are associated with karst rocky desertification (KRD), which can greatly impact soil structure and function. Despite the importance of soil microbes as a major factor maintaining ecosystem stability, we know little about the effect on soil fungal communities of KRD in karst regions. We investigated this relationship across a gradient of KRD soils from Guizhou, China by polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE). Fungal diversity indices (Shannon-Wiener, richness, and evenness) significantly differed (P < 0.05) based on KRD severity, being lowest in moderately affected areas. Cluster analysis showed that the five sites examined clustered into two main groups according to KRD grade (high and low). Moreover, a homology search using sequences recovered from PCR-DGGE bands showed that the dominant fungi in each community varied remarkably, and included Aspergillus, Aphanoascus, Blastomyces, Fusarium, Glomus, Geomyces, Gibberella, Mortierella, Tetracladium, and Tumularia species, and an unclassified group. In conclusion, these findings demonstrate that KRD has a significant impact on soil fungal communities.

Genetic diversity of Ceratoides arborescens, a species endemic to China, detected by inter-simple sequence repeat (ISSR).

In order to investigate genetic diversity and population structure of Ceratoides arborescens, six populations were selected from different steppe types in Inner Mongolia grasslands of China. Inter-simple sequence repeat (ISSR) markers were used to assess the genetic diversity within and among natural populations of C. arborescens. Thirteen ISSR primers generated 154 discernible DNA bands, of which 151 (98.05%) were polymorphic. High genetic diversity was detected at the species level [percentage of polymorphic loci (PPB) = 98.05%; H = 0.2984; I = 0.4557], whereas, relatively low genetic diversity existed within populations (PPB = 80.62%; H = 0.2675; I = 0.4031). Analysis of molecular variance showed that variation existed mainly within populations (73.25%) rather than among populations (26.75%), which was in line with the high level of gene flow (Nm = 4.3332). The Mantel test found no significant correlation between genetic distance and geographic distance (r = 0.7522, P < 0.05). Six populations were clustered into two main groups, a desert steppe group and a typical steppe group.