Characterization of Pectobacterium aroidearum Causing Konjac Soft Rot and Biocontrol Effect of Bacillus velezensis
CUI Shuang1，2，CHEN Changlong2，FENG Jiahao3，CAO Ying3，KOU Xiaomin2，FU Lu2，ZHANG#br# Rongping1*，XIE Hua2*
（1Tropical Crops College，Hainan University，Haikou 5702282，Hainan，China；2Beijing Agro-Biotechnology Research
Center，Beijing Academy of Agriculture and Forestry Sciences，Beijing 100097，China；3College of Life Science and
Engineering，Southwest University of Science and Technology，Mianyang 621010，Sichuan，China）
Abstract：This study isolated and purified 3 strains of konjac soft rot pathogen（ MY7，MY11 and MY18）
from the suffering plants grown in konjac production areas of Fuyuan and Chuxiong in Yunnan Province and
Yibin in Sichuan Province；determined the biological characteristics and phylogenetic systematics by analyzing
their morphological，pathogenic and molecular characteristics；and also evaluated the biocontrol effect of
Bacillus velezensis on konjac soft rot．The results showed that strains MY7，MY11 and MY18 could all produce
pectinase，belonging to motilegram-negative rod bacterium，and their PCR products with specific primers
were consistent with Pectobacterium aroidearum KC20．Based on the phylogenetic analysis of 16S rDNA and
pmrA gene sequences，these 3 strains were clustered with the known P. aroidearum strains together into one
clade，within the genus Pectobacterium．The genome-wide average nucleotide identity（ANI）values between
the 3 strains，and with P. aroidearum PC1 and KC20 strains were higher than the threshold（95%-96%） of
the same species．Therefore，these 3 strains were identified as P. aroidearum．Carbon source utilization
analysis by Biolog GEN III plates and several important physiological and biochemical tests showed that their
characteristics were mostly consistent with those of P. aroidearum SCRI 109T and P. aroidearum KC20．By
artificial inoculation，MY18 could infect multiple vegetable crops and ornamental plants，and all the tested 7 B.
velezensis strains could inhibit their growth in an plate antagonism assay．The biocontrol effect on konjac soft
rot caused by MY18 of B. velezensis strains （BPC16 and W2-7） were 43.01% and 31.99%，respectively under
greenhouse potting conditions，indicating that B. velezensis has potential to effectively biocontrol P. aroidearum．
