Expression of defence-related genes against Phytophthora cinnamomi in five avocado rootstocks

Authors

  • Juanita Engelbrecht Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
  • Noëlani van den Berg Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa

DOI:

https://doi.org/10.1590/sajs.2013/20120058

Keywords:

Phytophthora cinnamomi, gene expression, resistance, avocado, defence

Abstract

Avocado (Persea americana) – a major fruit crop worldwide – is threatened by root rot caused by Phytophthora cinnamomi. This pathogen is known to infect the plant via the feeder roots leading to branch dieback, and eventually tree mortality. While it is known that different avocado rootstocks have varying degrees of susceptibility to Phytophthora root rot, little research has been done on the avocado–Phytophthora interaction. In this study, transcript abundance levels of defence-related genes coding for phenylalanine ammonia-lyase, lipoxygenase, pathogenesis-related protein 5, endochitinase, gluthathionine S-transferase and metallothionein were characterised and compared among five rootstocks with varying susceptibility to root rot, after exposure to P. cinnamomi. Root samples were collected at 0 h, 3 h, 6 h, 12 h, 24 h, 48 h and 72 h post-infection and transcript abundance of the defence-related genes was determined using quantitative real-time reverse transcription PCR. The results indicated the involvement of PR-5 and endochitinase in the defence response of all avocado rootstocks to P. cinnamomi but these genes could not be directly linked to the observed phenotypic resistance. PR-5 and endochitinase were highly upregulated at 72 h post-infection. Differences in transcript abundance of phenylalanine ammonia-lyase and lipoxygenase genes were seen when comparing tolerant and less tolerant rootstocks, which may suggest that transcripts of these genes contribute to resistance. These data provide important insights into plant defence and into how different avocado rootstocks may exhibit increased resistance to infection by P. cinnamomi.

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Published

2013-11-27

How to Cite

Engelbrecht, J., & van den Berg, N. (2013). Expression of defence-related genes against Phytophthora cinnamomi in five avocado rootstocks. South African Journal of Science, 109(11/12), 8. https://doi.org/10.1590/sajs.2013/20120058

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Section

Research Article
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