Bacterial Microbiota Isolated from Cysts of Globodera rostochiensis (Nematoda: Heteroderidae).

Violeta Oro,Dusica Delic,Zoran Dinic,Magdalena Knezevic

doi:10.3390/plants9091146

Abstract

The potato cyst nematode (PCN) Globodera rostochiensis is a plant parasite of potato classified into a group of quarantine organisms causing high economic losses worldwide. Due to the long persistence of the parasite in soil, cysts harbor numerous bacteria whose presence can lead to cyst death and population decline. The cysts of G. rostochiensis found in two potato fields were used as a source of bacteria. The universal procedure was applied to extract DNA from bacteria which was then sequenced with 16S primers. The aims of the study were to identify bacterial microbiota associated with the PCN populations and to infer their phylogenetic relationships based on the maximum likelihood and Bayesian phylogeny of the 16S sequences. In addition, the impact of the most significant climate and edaphic factors on bacterial diversity were evaluated. Regarding the higher taxonomy, our results indicate that the prevalent bacterial classes were Bacilli, Actinobacteria and Alphaproteobacteria. Phylogenetic analyses clustered Brevibacterium frigoritolerans within the family Bacillaceae, confirming its recent reclassification. Long-term climate factors, such as air temperature, insolation hours, humidity and precipitation, as well as the content of soil organic matter, affected the bacterial diversity. The ability of cyst nematodes to persist in soil for a long time qualifies them as a significant natural source to explore the soil bacterial microbiota.

Highlights

Bacteria are ubiquitous organisms, inhabiting even the most extreme environments like polar snow [1], volcanoes and acidic hot springs [2,3]
Regarding the higher bacterial taxonomy, our results indicate that the observed locations have similar microbiota, but with a different abundance and species identity
Based on 16S sequences, the maximum likelihood and the Bayesian phylogeny clustered the members of the genus Bacillus, Psychrobacillus and Paenibacillus within the family Bacillaceae

Summary

Introduction

Bacteria are ubiquitous organisms, inhabiting even the most extreme environments like polar snow [1], volcanoes and acidic hot springs [2,3]. The potato cyst nematodes (PCNs) Globodera rostochiensis and G. pallida are plant parasites of potatoes and other Solanaceae plants, classified as quarantine organisms. PCN females are sedentary organisms living inside potato roots with numerous eggs within their enlarged spherical bodies called cysts. The nematodes develop within the eggs to first and second stage juveniles. The latter is the invasive stage, searching for the appropriate host plant. When they find a target host, they start to invade roots, penetrating the host tissue with their stylets and move inside it. New eggs and juveniles are produced within the cysts, so the parasitic cycle continues. The potato cyst nematodes cause up to GBP 300M worth of damage to the potato crop in the EU each year [6]

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