Research finds mechanism triggering flowering plants to produce fruits and seeds

Food production has grown more and more challenging for producers throughout the globe due to rising global temperatures and declining pollinator populations.

This question is addressed in a recent study from the Department of Cell Biology and Molecular Genetics at the University of Maryland, which also sheds light on the precise mechanisms by which flowering plants produce their fruits and seeds.

Understanding this process is especially important because common food crops—such as peanuts, corn, rice and strawberries—are all fruits and seeds derived from flowers. Knowing how plants ‘decide’ to turn part of their flowers into fruit and seed is crucial to agriculture and our food supply.”

Zhongchi Liu, Study Senior Author and Professor, Department of Cell Biology and Molecular Genetics, University of Maryland

The research was funded by the National Science Foundation and published on July 9^th, 2022, in the journal Nature Communications.

Liu and her research colleagues conducted the research with the goal of figuring out how fertilization—also known as pollination—causes a flowering plant to begin the fruit development process. The scientists believed that a system of internal communication was in charge of signaling the plant when to start producing fruit, but they were unaware of how fertilization or pollination triggered that system.

The scientists used strawberry plants to model pollination and fruit development processes in order to find out. According to Liu, strawberries’ distinctive structure and position of the seed make them especially well-suited for fertilization modeling.

As an ‘inside-out’ fruit, strawberry seeds are much easier to manipulate and observe than the seeds of other fruits like tomatoes. This made it easier for us to view the seeds and extract genetic information from them at multiple stages of plant development.”

Zhongchi Liu, Study Senior Author and Professor, Department of Cell Biology and Molecular Genetics, University of Maryland

AGL62, a gene that is present in every flowering plant, was discovered by Liu and her colleagues to be the gene that causes a plant to produce fruit and seeds.

AGL62, according to Liu, increases the synthesis of auxin, a crucial plant growth hormone. Auxin is produced as soon as the gene is activated, which causes the development of the seed coat, the endosperm, and the fruit of the plant. The seed coat is the outer protective shell of the seed. For researchers, the function of auxin in controlling endosperm development is very important since it affects the size of the grain and the growth of the fruit.

Auxin levels can limit how big an endosperm can grow and how much nutrition endosperm can accumulate for a plant embryo. More auxin can boost grain size and stimulate fruit enlargement. When there’s less auxin, endosperms are unable to feed plant embryos properly and we end up with lowered crop productivity—smaller or deformed fruits that aren’t commercially viable.”

Zhongchi Liu, Study Senior Author and Professor, Department of Cell Biology and Molecular Genetics, University of Maryland

Lei Guo, the first author, effectively interfered with the AGL62 function using the cutting-edge gene-editing method CRISPR. The inability of the strawberry plants to produce fruit and seed illustrates the crucial function of AGL62 in this process.

In nature, pollination causes the AGL62 gene to start producing auxin, which is essential for the best possible growth of the fruit and seed. But Liu and her colleagues have created the groundwork for agriculturalists to turn on AGL62 using biotechnology, avoiding pollination altogether—creating “virgin” fruits—by establishing this link between gene and hormone.

These results, in Liu’s opinion, are particularly significant at this time when global warming is affecting food production all across the globe.

“Extreme heat kills both pollinators and pollen itself, so climate change is a big challenge for us to overcome. Learning more about the AGL62 gene has given us new insight into how to potentially increase the productivity of agricultural crops, particularly the ones that make up our food supply,” Liu concluded.