关键词: 黔西北地质高背景区, 重金属, 马铃薯晚疫病, 根际土壤, 真菌

Abstract: Weining is a typical county with both high geological background and heavy metal pollution in Northwest Guizhou. Potato (Solanum tuberosum) production is one of the important agricultural industries in the county. There is high incidence of potato late blight caused by Phytophthora infestans. Here, we investigated the response of the rhizosphere soil microbial community to the occurrence of potato late blight in the context of high heavy metal geology. The fungal community composition and diversity of rhizosphere soil of potato late blight infected plants and healthy plants of different cultivars were analyzed by Illumina Hiseq high-throughput sequencing technology. The results showed that soil Cd concentration ranged from 1.75 to 2.67 mg·kg^-1, showing a serious contamination. Cr, Ni, and Zn were also slightly contaminated. The incidence of late blight in different potato cultivars was in an order of Weiyu 3 (21%) > Weiyu 5 (13%) > Qingshu 9 (5%). The dominant fungi in the rhizosphere soil of potato plants infected with late blight were Ascomycota and Mortierellomycota at the phylum level and Mortierella and Penicillium at the genus level. There was no difference for αdiversity of fungal community between plants with and without late blight infection for the three cultivars. Among the late blight infected plants, the resistant cultivar Qingshu 9 showed a higher fungal community diversity in the rhizosphere soil, while the sensitive cultivar Weiyu 3 showed a lower fungal community diversity and a higher relative abundance. Results of principal coordinates analysis showed that rhizosphere soil fungal community structure of potato late blight infected plants and healthy plants was significantly separated. The results of redundancy analysis showed that soil Cd content and pH greatly affected fungal community composition of rhizosphere soil. The proportion of dominant fungi phyla and genera in the rhizosphere soil of potatoes infected with late blight was changed under the contamination by heavy metals. There were more pathogenic fungi in the rhizosphere soil of Weiyu 3 potato with low disease resistance, which may have direct or indirect effects on the occurrence of potato late blight.

Key words: high geological background area in Northwest Guizhou, heavy metal, potato late blight, rhizosphere soil, fungal community.