Program

Rhizospheric microbial communities play vital role in C, N and S cycling in wetland ecosystems and influence the mechanism of plant growth. In the southernmost part of Guangdong Province (China), two height forms Spartina alterniflora, high Spartina and short Spartina, have manifestly invaded Leizhou peninsula. However, the mechanism that leads to different height forms has not been clearly clarified. The community structures of rhizosphere bacteria associated with selected S. alterniflora were investigated using the barcoded Illumina paired-end sequencing and the abundance of the key nitrogen cycling functional genes like nifH, amoA, nirS and nosZ were targeted using qPCR assays in this study. The diversity indices of high S. alterniflora and short S. alterniflora rhizosphere soil have no significant difference, but notably higher than bulk soil. The comparison of β-diversity revealed that high S. alterniflora presented partial similarity with short S. alterniflora, but completely segregated from bulk soil. Proteobacteria, Chloroflexi, Bacteroidetes, and Acidobacteria were the top 4 dominant phyla in the rhizoplane of two salt marsh plants. The copy numbers of nitrification and denitrification genes in high Spartina were significantly higher than that in short Spartina, which revealed the notable different characterization of nitrogen cycling between two different growth forms S. alterniflora. We hypothesized that such conditions may enhance the expansion of the short S. alterniflora habitat consuming most of the available nitrogen in soils, while high S. alterniflora will gradually decrease. The results would provide clues to investigate factors affecting Spartina growth.