Diversity and Function of Endo-Bacteria in Bursaphelenchus xylophilus from Pinus massoniana Lamb. in Different Regions

Abstract

The pine wood nematode (PWN) Bursaphelenchus xylophilus is the pathogen that causes pine wilt disease (PWD), a devastating forest disease. PWN-associated bacteria may play a role in PWD. However, little is known about the endo-bacteria in PWN. We analyzed the diversity of endo-bacteria in nine isolates of PWNs from Pinus massoniana Lamb. in nine epidemic areas from three Chinese provinces by high-throughput sequencing of 16S rDNA and isolated and identified culturable endo-bacteria through construction of a 16S rDNA phylogenetic tree and Biolog microbial identification. We also examined the effects of endo-bacteria on PWN fecundity, antioxidant capacity, and virulence using sterile nematodes as a control. While the dominant endo-bacteria in PWNs from different regions exhibited no significant difference in the classification levels of class and genus, their proportions differed. Pseudomonas and Stenotrophomonas were highly abundant in all PWN isolates. A total of 15 endo-bacterial strains were successfully isolated and identified as six species: Stenotrophomonas maltophilia, Pseudomonas fluorescens, Kocuria palustris, Microbacterium testaceum, Rhizobium radiobacter, and Leifsonia aquatica. We also found that P. fluorescens significantly increased the egg production of PWN, and that both P. fluorescens and S. maltophilia enhanced the mobility of PWN under oxidative stress and reduced the content of reactive oxygen species by increasing antioxidant enzyme activity in PWN. These strains also accelerated the development of PWD, and P. fluorescens had a more beneficial effect on PWN than S. maltophilia. Diversity exists among the endo-bacteria in PWNs from different regions, and some endo-bacteria can promote PWN infestation by enhancing the fecundity and antioxidant capacity of the nematode. Our study contributes to clarifying the interaction between endo-bacteria and PWN.

Endosymbiotic bacteria within the nematode-trapping fungus Arthrobotrys musiformis and their potential roles in nitrogen cycling

“…In addition, Fu et al (2020) investigated the diversity and function of endo-bacteria in Bursaphelenchus xylophilus by high-throughput sequencing of 16S rDNA and isolated culturable endo-bacteria, and bacteria belonging to six genera, which, respectively, were Stenotrophomonas , Pseudomonas , Kocuria , Microbacterium , Rhizobium , and Leifsonia , were obtained. They found that P. fluorescens significantly increased the egg production of pine wood nematode, and that both P. fluorescens and St. maltophilia enhanced the mobility of pine wood nematodes under oxidative stress.…”

“…Genomic DNA of all isolated ESB was extracted as described by Pakvaz and Soltani (2016) . The 16S rDNA was amplified by PCR using the universal primers 515F and 806R as described by Fu et al (2020) and sequenced by the above LI-COR 4000 L automatic sequencer. Furthermore, the bacterial sequences of each representative species were deposited in GenBank ( Supplementary Table S7 ).…”

Two Nematicidal Compounds from Lysinimonas M4 against the Pine Wood Nematode, Bursaphelenchus xylophilus

“…The levels of other antioxidant enzymes, such as glutathione peroxidases (GPX), are worthy of further study for further elucidating the mechanism of the nematicides isolated from Lysinimonas sp. M4 [54].…”