Identification and characterization of pathogenicity of Lelliottia nimipressuralis causing soft rot of Codonopsis pilosula (dangshen) roots in China

Abstract

The roots of Codonopsis pilosula, a crucial ingredient in Chinese medicine, are prone to soft rot disease soon after transplanting seedlings in the second year. This almost always causes severe losses in yield at harvest, with severe economic consequences for farmers of this perennial vine. However, the pathogens involved remain understudied, although some gram‐negative bacteria of the Enterobacteriaceae family are well‐known pathogens of soft rot in many other plants. Here, the isolate B5‐2‐1‐30 was suspected of being a key pathogen of C. pilosula in China according to counts of bacteria from diseased, healthy and adjacent tissues of roots. Results of morphological and phylogenetic analyses, including microscopic observations, in addition to a multilocus sequence analysis (MLSA) of the concatenated partial 16S rDNA, rpoB, atpD and gyrB genes, revealed that this isolate belongs to Lelliottia nimipressuralis. In vitro and in vivo pathogenicity tests showed that L. nimipressuralis B5‐2‐1‐30 could cause root soft rot in seedlings of C. pilosula, with symptoms similar to those observed in the field. Further experiments suggested the typical symptoms of softened rotting roots and wilting shoots arose from phloem necrosis and vessel plugging, as inferred by observed anatomical characteristics of roots, providing clues for elucidating the infection mechanism of phytopathogens in L. nimipressuralis.

Adaptation of plant protection technology considering fungalbacterial associations

“…Штамм РС3 Lelliottia amnigena {OK447935} был найден на клубнях картофеля (Solanum tuberosum L.) с мацерированной мякотью и явными признаками бактериального поражения в окрестностях города Ланьчжоу (Китай) [6]. Другой вид патогенной Lelliottia обнаружен на растении из семейства колокольчиковых Codonopsis pilosula в Китае [7]. В штамме Fusarium oxysporum, выделенном из клубня картофеля, выращенного в Уганде, мы обнаружили бактерии, относящиеся к роду Kosakonia {OL762470}.…”

Changes of Key Soil Factors, Biochemistry and Bacterial Species Composition during Seasons in the Rhizosphere and Roots of Codonopsis pilosula (tangshen)

“…Hence, how to improve the quality and yield of C. pilosula and how to further explore the effects of biotic or abiotic stress on plant rhizosphere microecology, plant growth, development and accumulation of metabolites has become a hot research topic at present. Many scholars have devoted themselves to research on the environmental conditions and microorganisms affecting growth and development of C. pilosula [10,11], and some main pathogenic bacteria for C. pilosula root were obtained and identified [11]; meanwhile, beneficial soil microbes promoting seed germination, plant growth and photosynthesis of C. pilosula have also been obtained [12]. Internal and external factors affecting the growth of C. pilosula have been independently explored by many different research groups.…”