Africa in bloom: the key to fighting plant disease

The Forest and Agricultural Biotechnology Institute (FABI) at the University of Pretoria is leading research into plant pathogens and pests. Plants provide food, feed, and fibre, and maintaining plant health influences societal outcomes, from creating sustainable jobs to alleviating poverty. Ahead of the 52nd Southern African Society of Plant Pathology conference, hosted by FABI in August 2022, founding faculty member, Brenda Wingfield, discusses why every country in Africa needs local scientists trained in plant pathology, disease management and biosecurity.

FABI supports South Africa’s forestry industry and agricultural sector through high quality research and capacity development. Forest plantations of imported pine and eucalypts represent around 1% of the country’s GDP and more than 150,000 jobs, while agriculture contribute around 2.5% to GDP and more than 600,000 jobs. One of FABI’s primary focuses is diagnostics – identifying pathogenic threats and tracking their spread and evolution. Many pests and pathogens are native to South Africa, several have followed imported plants, and some native pest and pathogens also cause disease on these imported plants. At FABI, we interact with scientists in Africa and across the world, sharing knowledge of emerging pests and pathogens and developing integrated solutions for their management.

What is a plant pathogen?

Like animals, plants are susceptible to infection by organisms like fungi, bacteria and viruses. Many plant pathogens are microfungi, which are practically invisible to the human eye. They don’t sprout fruiting structures, and people often don’t realise plants are infected. Expertise and advanced technologies are needed to recognise when microfungi are attacking plants. There are millions of fungi species, so we need to understand which are dangerous, and which can be good for plants.

How do plant pathogens impact society?

Plants provide food, feed and fibre. Entire crops can be wiped out because of pathogens, and while quarantine systems do an excellent job, we will always have porous borders. Wind can bring new pathogens from neighbouring regions. We've recently developed a grain research programme in collaboration with other universities, backed by South Africa’s maize, soybean, and sunflower industries. Farmed animals also need feed that is free from toxins, and there are some nasty toxins produced by fungi, so farmers need clear advice regarding potential threats. Also, our lives are literally built around wood fibre. Wood-based industries rely on healthy forests to stay lucrative and pay wages. Working in plant pathology can help alleviate poverty on all these fronts.

How are plant pathogens managed?

DNA sequencing technology allows us to identify pathogens and their variants efficiently – and often lead us to discover new species. Closely related species, and the diseases they cause, can manifest in various ways and require different management strategies. We can now identify precise genes that are facilitating disease progression, and tools like CRISPR-Cas9 enable us to edit genomes and manipulate plants, so that they can resist specific diseases. We can even identify the presence of pathogens in asymptomatic plants. Pathogens that are recently imported are often easier to tackle –native pathogens can be more difficult because they’ve evolved alongside native plants. Local scientists are invaluable assets in recognising regional variants and disease.

Why are local experts key to disease management?

Every country needs trained plant pathologists with sound knowledge of their local patch, who will react quickly if they spot unusual activity – otherwise, potential threats may be overlooked. Countries with higher GDPs often have more reported pathogens because they have resources to find them. FABI is committed to providing scientists with extensive training on diseases found across Africa. Thanks to FABI and local researchers in South Africa, plant pathogens are now being increasingly reported.

Describe some of FABI’s success stories.

We’re leading research on the pitch canker pathogen, Fusarium circinatum, which causes excessive resin to ooze from pine trees and problems with pine seedlings. We first sequenced its genome 10 years ago, and now we’re collaborating with universities around the world on the issue – to expand our understanding of the organism. FABI has also recently secured government funding to examine the invasive Polyphagous shot hole borer beetle and its fungal symbiont, which is causing huge problems in the country, and in cities such as Johannesburg, which is one of the world’s largest urban forests. One of FABI’s greatest assets is our bio-control facility for tackling insect pests. Insects often arrive without their natural predators and parasites, meaning they multiply unchecked. Parasitic organisms are often best to manage these emerging pests in an environmentally friendly and sustainable manner.

Why work in plant pathology?

Plant Pathology is a varied career incorporating many foundational disciplines within a global community solving critical problems. We need people who can apply the latest molecular and digital technologies in creative ways, and we must also invest in analysts for the vast quantities of data that these technologies produce, to ensure a sustainable future. Biology is one of the fastest growing fields of science, and pathogens are always evolving. There is exciting and ever increasing work for plant pathologists to do.