Survival, growth and detection of Pseudomonas syringae pv. actinidiae in Actinidia in vitro cultures

ABSTRACT

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker of kiwifruit, currently the most important disease of Actinidia species worldwide. Due to the risk of Psa being associated with plant material moved from Psa-affected regions, there is a need to understand the behaviour and survival of Psa within tissue cultured plants, and identify detection or intervention points within the propagation process. In this study, we evaluate the ability of Psa to grow on plant culture media, assess the movement of Psa within in vitro growing plants, investigate the detection threshold of Psa and model the likelihood of false negatives when screening for Psa. Following inoculation of in vitro growing plants, even of genotypes considered Psa resistant, the bacteria spread rapidly through growing shoots. Standard plant tissue culture media did not support easily visible growth of Psa, however, supplementing these with peptone promoted Psa growth, providing a rapid, non-destructive visual indicator of its presence.

KEYWORDS:

• Epidemiology
• kiwifruit bacterial canker
• peptone
• tissue culture

Acknowledgements

We gratefully acknowledge the support of Andrew Mullan and Belinda Diepenheim for providing plant tissue culture media, and Maree Debenham for producing some of the tissue culture plants used in this work.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Joy L. Tyson http://orcid.org/0000-0002-0547-1093

Ruth C. Butler http://orcid.org/0000-0001-8646-1147

Ed R. Morgan http://orcid.org/0000-0002-5353-2639

Additional information

Funding

This work was supported by Zespri and The New Zealand Institute for Plant & Food Research.