PhD Precis: Damola Adejoro

"However, the fact is that only a tiny proportion of microorganisms cause problems," says the Lincoln University PhD student researching the microbiome structure and function of "disease-escape grapevines" - grapevines thriving in an environment where there is heavy pressure of grapevine trunk diseases.

What led you to this PhD programme?

I was interested in knowing how to make use of the good microorganisms and reduce the hrmful impacts of the bad ones. Fuelled by the bad reputation of microorganisms, I decided to study microbiology. During my MSc at the University of Ilorin, Nigeria, I focused on the industrial application of fungi, in line with my passion for utilising microorganisms. When the opportunity for this PhD position in New Zealand came my way, I was excited about its potential because it fitted seamlessly with the enthusiasm I had as an undergraduate student of microbiology.

Why are grapevine trunk diseases such a concern?

According to recent figures from Fresh Facts, wine exports contribute $1.9 billion to the New Zealand economy - second only to kiwifruit among horticultural products. However, grapevine trunk diseases (GTDs) are one of the gravest threats to the continued profitability of wine producers, not only in New Zealand but also in other grape growign regions across the globe. These diseases are caused by a complex of fungi, and their control is difficult. Unfortunately, there is currently no approved fungicide for their eradication.

What are you doing to address the trunk diseases problem?

Due to limited control options for GTDs, researchers have sought alternative control strategies, including sustainable biological controls. In my research, I am trying to manipulate the microbiome, or the whole microbial community of the grapevine trunk, as a means of controlling GTDs. The microbiome is crucial to the health and productivity of plants. Recently, a key international work identified grapevines that could escape Pierce's disease, and this was linked to microbiome function. Anecdotal evidence from New Zealand growers and data from grapevine disease mapping in Hawke's Bay and Marlborough have also suggested that some grapevines can escape trunk diseases. These healthy vines growing robustly among diseased vines are defined as disease-escape grapevines. My study is aimed at identifying the collections of microorganisms within these disease-escape grapevines and seeing if we can use them to protect other vines against GTD fungi.

How do you do that?

We firstly identified candidate disease-escape grapevines across vineyards in the Marlborough, Hawke's Bay and Canterbury regions, took samples from these vines and their diseased neighbours and then compared their microbial communities. I employed two methods to identify the microbial community. Firstly, I grew and identified microorganisms in the lab. Secondly, I used DNA metabarcoding to simultaneously identify numerous microorganisms (more than we can ever grow in the lab) in the communities. These two approaches complement each other, giving us both a tonne of data about the microbial communities, and also providing microbial isolates that we can study as inoculants.

What's next?

I'm currently doing pathology assays on grapevine plants inoculated with the microorganisms from disease-escape vines. We will monitor the growth of the microorganisms over a season to see if they can establish and keep out trunk disease pathogens. By the end of my research, we'd like to have a cocktail of the beneficial microbes that together can reduce the damage caused by GTDs.

What support have you had for this work?

My research is funded by the Ministy of Business, Innovation and Employment's Strategic Science Investment Fund (SSIF) through Plant & Food Research Ltd, Lincoln. My research is supervised by Professor Eirian Jones (Lincoln University), Associate Professor Hayley Ridgway (Lincoln University and Plant & Food Research Ltd, Lincoln) and Dr Simon Bulman (Plant & Food Research Ltd, Lincoln), with Dion Mundy (Plant & Food Research Ltd, Blenheim) in an advisory role.