Isolation and Genome Analysis of Pectobacterium colocasium sp. nov. and Pectobacterium aroidearum, Two New Pathogens of Taro

Abstract

Bacterial soft rot is one of the most destructive diseases of taro (Colocasia esculenta) worldwide. In recent years, frequent outbreaks of soft rot disease have seriously affected taro production and became a major constraint to the development of taro planting in China. However, little is known about the causal agents of this disease, and the only reported pathogens are two Dickeya species and P. carotovorum. In this study, we report taro soft rot caused by two novel Pectobacterium strains, LJ1 and LJ2, isolated from taro corms in Ruyuan County, Shaoguan City, Guangdong Province, China. We showed that LJ1 and LJ2 fulfill Koch’s postulates for taro soft rot. The two pathogens can infect taro both individually and simultaneously, and neither synergistic nor antagonistic interaction was observed between the two pathogens. Genome sequencing of the two strains indicated that LJ1 represents a novel species of the genus Pectobacterium, for which the name “Pectobacterium colocasium sp. nov.” is proposed, while LJ2 belongs to Pectobacterium aroidearum. Pan-genome analysis revealed multiple pathogenicity-related differences between LJ1, LJ2, and other Pectobacterium species, including unique virulence factors, variation in the copy number and organization of Type III, IV, and VI secretion systems, and differential production of plant cell wall degrading enzymes. This study identifies two new soft rot Pectobacteriaceae (SRP) pathogens causing taro soft rot in China, reports a new case of co-infection of plant pathogens, and provides valuable resources for further investigation of the pathogenic mechanisms of SRP.

Complete mitochondrial genome assembly and comparative analysis of Colocasia esculenta

“…The number of studies on mitochondrial genomes increased from 291 sequenced genomes in 2020 to 400 genomes by 2023 [22]. However, the C. esculenta genome sequence has been widely used for analyzing diseases in many studies [23][24][25]. There are currently no reports on the mitochondrial genome of C. esculenta.…”

Pectobacterium and Dickeya genus—A review on structural variations of O‐polysaccharides and their role in the pathogenic process of plants

“…The development of disease symptoms depends primarily on the secretion of extracellular cell wall-degrading enzymes such as proteases, pectinases and cellulases. The virulence of phytopathogens is also often associated with the type III secretory system (T3SS) (Zhou et al, 2022). Interestingly, unlike the Dickeya genus, some Pectobacterium strains do not require the T3SS for pathogenicity.…”

“…and Dickeya spp. that play roles in setting up disease symptoms include formation of biofilm, production of siderophores and the presence of lipopolysaccharides (LPSs) (Zhou et al, 2022). In particular, the outer sugar part of the LPSs, namely O ‐polysaccharides (OPSs), is important for bacterial virulence.…”

Polyamine signaling communications play a key role in regulating the pathogenicity of Dickeya fangzhongdai

“…Taro is an edible tropical crop belonging to the Araceae family, which is widely distributed throughout the world and has high nutritional, ornamental, medicinal, and economic values ( 35 ). However, its plantation has been severely affected by bacterial soft rot disease caused by various bacterial pathogens ( 36 ). We recently found that D. fangzhongdai is one of the major pathogens causing taro soft rot disease in Guangdong Province of China ( 13 ).…”