Researcher Aims to Alleviate Global Hunger by Deciphering the Molecular 'language' of Plants

As a young child spending time on her grandparents' rice farm in the Philippines, Shelley Lumba grew up understanding the benefits of the Green Revolution—the period in the 1950s and 60s when many technological advances were made in agriculture.

"My grandparents told stories about how we didn't have enough rice to feed our family, much less sell in the market," she says. "And the Philippines was facing the same crisis—there wasn't enough rice to feed the country's population. Of course, it was hitting the poorest people hardest and it was happening in countries around the world."

Then, Lumba's grandparents began growing a hybrid strain of rice—one of the newly developed varieties of cereals that were hardier, more nutritious and produced higher yields. Thanks to the hybrid, Lumba's grandparents were able to feed their family and had rice leftover to sell.

Today, Lumba is an assistant professor in the University of Toronto's department of cell and systems biology (CSB) in the Faculty of Arts & Science. She hopes her research will lead to advances in agriculture like those made during the Green Revolution and help alleviate hunger, poverty and climate change.

Lumba and her colleagues study how organisms—even those from completely different kingdoms—communicate on a molecular level through a shared "language of life." For example, plants signal fungi in the soil by giving off hormones called strigolactones (SLs). These "come-hither" hormones trigger the fungi to latch on to the plant, thus establishing a symbiotic relationship in which the fungi provide phosphates to its partner and, in return, receives carbon.

"This symbiosis is ubiquitous," says Lumba. "If you're a gardener, you know that new, sterile soil feels like sand, but soil from your planted pots or garden feels heavy with 'stuff.' That stuff is all the different fungi and bacteria helping your plants grow."

SLs and other plant hormones such as gibberrellins trigger germination when conditions are favorable—for example, when there's sufficient moisture and nutrients in the soil.

Lumba's goal is to better understand how, at a molecular level, organisms send out these signals and, once received, how those signals are translated into a response. One hope is that the research will lead to new ways of combatting the blight caused by the parasitic Striga hermonthica, commonly known as witchweed.

Witchweed—aka the "violet vampire" for its bright flowers—is considered by the United Nations to be a major impediment to poverty alleviation in Africa. The parasite attacks major cereal crops such as maize, sorghum, millet, sweetcorn and rice, latching on to their roots and draining the host of moisture and nutrients.

Witchweed is particularly difficult to combat because a single plant is capable of producing up to 100,000 seeds. The seeds are so tiny they resemble dust and a square-meter patch of ground can contain thousands. What's more, the parasite begins to damage crops even before sprouting above ground—in other words, before farmers even know their crops are under attack.

Witchweed can lead to significant crop losses and can sometimes wipe out entire harvests. Damage to agriculture in Africa caused by the plant is estimated at approximately US$9 billion a year, with infestations affecting the lives of over 100 million people in 25 countries.

Like any parasitic organism, witchweed needs a host in order to survive and so it has evolved seeds that can remain dormant in the ground for decades until they "sense" that a potential victim is nearby. At that point, the seeds germinate and latch on to a host.