Microbial Diversity in the Edible Gall on White Bamboo Formed by the Interaction between Ustilago esculenta and Zizania latifolia

An edible gall is formed between the third and fourth nodes beneath the apical meristem near the base of Zizania latifolia shoots. This gall is harbored by and interacts with the smut fungus Ustilago esculenta. The gall is also a valuable vegetable called "white bamboo," jiaobai or gausun in China and makomotake in Japan. Five samples of the galls harvested at different stages of swelling were used to isolate microorganisms by culturing. Isolated fungal and bacterial colonies were identified by DNA sequencing and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry, respectively. Several strains of U. esculenta as well as 6 other species of fungi and 10 species of bacteria were isolated. The microbiome was also evaluated by simple and outlined DNA profiling with automated rRNA intergenic spacer analysis (ARISA), and the amount of DNA of U. esculenta was determined by qPCR. At least 16 species of fungi and 40 species of bacteria were confirmed by ARISA of the overall sample. Interestingly, the greatest bacterial diversity, i.e., 18 species, was observed in the most mature sample, whereas the fungal diversity observed in this sample, i.e., 4 species, was rather poor. Based on qPCR, U. esculenta occurred in samples from all stages; however, the abundance of U. esculenta exhibited unique U-shaped relationships with growth. These results may explain why the interaction between U. esculenta and Z. latifolia also influences the unique microbial diversity observed throughout the growth stages of the swollen shoot, although the limited sample size does not allow conclusive findings.