RESUMO
Fusarium wilt (also known as Panama disease) is one of the most destructive banana diseases, and greatly hampers the global production of bananas. Consequently, it has been very detrimental to the Chinese banana industry. An infected plant is one of the major causes of the spread of Fusarium wilt to nearby regions. It is essential to develop an efficient and environmentally sustainable disease control method to restrict the spread of Fusarium wilt. We isolated Trichoderma spp from the rhizosphere soil, roots, and pseudostems of banana plants that showed Fusarium wilt symptoms in the infected areas. Their cellulase activities were measured by endoglucanase activity, ß-glucosidase activity, and filter paper activity assays. Safety analyses of the Trichoderma isolates were conducted by inoculating them into banana plantlets. The antagonistic effects of the Trichoderma spp on the Fusarium pathogen Foc tropical Race 4 (Foc TR4) were tested by the dual culture technique. Four isolates that had high cellulase activity, no observable pathogenicity to banana plants, and high antagonistic capability were identified. The isolates were used to biodegrade diseased banana plants infected with GFP-tagged Foc TR4, and the compost was tested for biological control of the infectious agent; the results showed that the fermentation suppressed the incidence of wilt and killed the pathogen. This study indicates that Trichoderma isolates have the potential to eliminate the transmission of Foc TR4, and may be developed into an environmentally sustainable treatment for controlling Fusarium wilt in banana plants.
Assuntos
Fermentação , Fusarium/fisiologia , Musa/microbiologia , Doenças das Plantas/microbiologia , Trichoderma/fisiologia , Bioensaio , Proteínas de Fluorescência Verde/metabolismo , Filogenia , Folhas de Planta/microbiologia , Caules de Planta/microbiologia , Trichoderma/isolamento & purificaçãoRESUMO
Placusa pinearum, a newly described beetle species found living in pine shoot tunnels bored by the pine tip moth, Dioryctria rubella (Pyralidae), has potential as a vector to transport biological agents for controlling this moth pest of pine trees because of the high degree of niche overlap (co-occurrence) between them. In order to help determine the suitability of potential biological control vectors, it is useful to obtain knowledge concerning the intraspecific variation of the vector. We examined P. pinearum collected from 14 different geographical populations in China using morphological and molecular markers. An UPGMA dendrogram based on morphological characters showed divergence of populations of P. pinearum in a comparison of beetles from southwestern and 3 other geographic regions (central, northwestern, and eastern regions). We also compared 965-nucleotide sequences of the mitochondrial cytochrome oxidase subunit I gene from 56 individuals; 19 haplotypes were identified based on 28 polymorphic sites in this region. A Bayesian phylogenetic tree showed significant genetic divergence among the different populations in eastern China. In addition, absence of shared haplotypes, coupled with high pairwise FST values, demonstrated significant genetic divergence between the populations from the southwest and the other 4 main geographical regions (eastern, southern, central, and northwestern regions). Generally, we found the morphological divergence to be congruent with genetic divergence in these P. pinearum populations. This information should be useful for selection of suitable source materials in the species gene pool for future biological control programs.