Dr Jay Jayaraman has been awarded a Rutherford Foundation postdoctoral fellowship for research into long-term durability of kiwifruit to the bacterial disease Psa.

14 November 2019

From 2008-2012, Psa (Pseudomonas syringae pv actinidiae) swept through New Zealand’s kiwifruit industry causing severe crop losses, particularly in gold kiwifruit crops. The industry bounced back by introducing a cultivar with improved tolerance to the disease and applying copper-based sprays. These measures currently manage the spread of Psa but there are concerns on the long-term sustainability of copper-based sprays for the environment and so the industry continues to explore alternatives to give growers additional options to mitigate the ongoing risk of Psa. Furthermore, there is the real risk that Psa will adapt to the new cultivar, allowing the disease to cause widespread harm again.

Like other plant and animal pathogens, Psa causes disease by secreting proteins known as effectors that suppress their host’s defence response – in this case the kiwifruit plant. The host works in response to identify and defend against effectors using R-genes. In a continual arms race, pathogens adapt their effector suite, evolving it to be potent and specialised. Equally, R-genes defend against these specific effectors by bestowing long-lasting resistance to their hosts.

Plant & Food Research postdoctoral scientist Dr Jay Jayaraman is undertaking research which aims to identify the first Psa-resistant R-gene system that is naturally present in some non-industrial kiwifruit species, with the ultimate goal of breeding a durable commercial cultivar. This requires developing a deep understanding of the interaction between kiwifruit and Psa. Using molecular genetics, gene-knockout, and gene-replacement techniques, Dr Jayaraman will identify the effectors and corresponding R-genes that trigger resistance. Additionally, he will determine which R-genes are the ones that recognise and target the most pernicious effectors, to ensure the durability of a future Psa-resistant cultivar. Once identified, fast and accurate natural breeding strategies can be used to develop a new cultivar for orchards in Aotearoa that have long-term resistance to Psa, eliminating the need for chemical controls.

To hear more from Dr Jayaraman about his science career and research interests, listen to his Science Life for Me podcast on our Scigest podcast channel [link to https://www.plantandfood.co.nz/page/news/podcast-index/podcast/bitten-by-the-science-bug/], also available on iTunes and other podcast channels.

Emma Timewell
Communications Manager, Corporate Communications,
Plant & Food Research Mt Albert,
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