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Gazzarrini’s seed research could improve crops

by Kurt Kleiner

Sonia Gazzarrini, UTSC professor in the Department of Biological Sciences, is untangling the complexities that underlie seed formation in plants. Her work could eventually lead to crops that are more productive, or more resistant to heat or drought.

In a series of papers, including two recently in the prestigious The Plant Journal, Gazzarrini and her team have made progress in understanding the mechanisms that control seed formation, including factors such as how densely a seed packs nutrients, when it begins and ends dormancy, and how it behaves at different temperature and moisture levels.

“Prof. Gazzarrini’s work is answering important basic questions about seed formation, and eventually could lead to improved crop varieties,” says Malcolm Campbell, UTSC vice-principal, research.

Since about 60 percent of the human food supply comes from seeds, mostly in the form of grains such as rice, wheat and maize, being able to understand and control seed development would give researchers tools to improve crops.

The work could also be useful for conservation efforts, and for making predictions about the effects of climate change on different plant species.

“It shines a light on factors that may determine where plants are distributed,” Campbell says. “Given the likely impact of climate change, this could be important in the future for understanding and predicting global biodiversity.”

Part of the work involves understanding the role of two hormones, abscisic acid (ABA) and gibberellic acid (GA). ABA slows growth and helps prevent dormant seeds from germinating too quickly – a phenomenon known as pre-harvest sprouting – which leads to downgrading of grain quality and substantial financial losses. GA plays the opposite role, signaling to seeds when it’s time to germinate. When and how the hormones behave depends on a number of internal mechanisms and external cues.

For instance, in the model plant Arabidopsis which Gazzarrini works with, seeds exposed to supraoptimal (high) temperatures of 32C will germinate, but the shoots will die. By manipulating the levels of enzymes in the plant that effect hormonal signaling, Gazzarrini produced seeds that did not germinate prematurely under the higher temperatures, but were able to resume growth when the temperature dropped to optimal level. Work along those lines might create plants that are more tolerant to higher temperatures or less water.

But the interactions among the different genes, enzymes and hormones are complicated, since each is likely to affect more than one characteristic of the plant. Nevertheless, Gazzarrini would like to begin experimenting with crop plants such as canola and rice soon, work which could eventually lead to better varieties of these crops.

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