Recently awarded a five-year, multi-million dollar grant from the National Science Foundation, Blackman and his associates are excited to start research on the internal and external cues that guide sunflower and lettuce reproduction. Blackman and his group will perform genetic mapping experiments to localize genetic variants affecting the timing of reproductive development and pollinator attraction for the sunflower and lettuce plants. His collaborators, Stacey Harmer (UC Davis) and Jessica Barb (Iowa State), will study how circadian rhythm and environmental factors affect gene expression levels in sunflower and lettuce floral organs as they mature and research the efficiency of self-pollination in sunflowers, respectively.
The research to be conducted with this grant extends from previous experiments with sunflowers that led Harmer, Barb, and Blackman to further question the role of circadian and environmental regulation of solar tracking by sunflower stems and how the mature disk stops facing an eastward orientation when sunflower plants bloom. Although each PI is taking on different experiments within the project, they all have the same overarching goal: to understand the regulatory mechanisms affecting the daily cycles by which individual florets in a sunflower or lettuce floral disk mature and use this understanding to uncover information about cross and self-pollination.
As mentioned the researchers will be conducting experiments on both sunflowers and lettuce, but why is lettuce such a good juxtaposition for the vibrant sunflowers? Lettuce has a self-mating system where the development of the male and female floral organs is aligned in time so that self-pollination may happen, making the next generation of lettuce plants near-clones of the parent plant. This contrasts well with sunflowers, which generally utilize a two-day cross-pollination mating system in which the pollen is ready and presented on Day 1 and the stigma is open to fertilization on Day 2. The cross-pollination system means pollen from one flower is used to create seeds in another flower, thus producing hybrid plants different from the parents.
Among other differences between the two plants, the petals of sunflower florets remain open once a bud opens. In contrast, lettuce flower petals open and then close again in regular daily cycles, giving researchers the chance to study another plant process possibly affected by circadian or environmental factors. Like the sunflower, lettuce is also a well-researched crop with a sequenced genome, allowing researchers to pinpoint genes that play key roles in pollination and reproduction efficiency.
With food security and agricultural sustainability playing a huge role in many plant biologist’s research, Blackman, Harmer, and Barb will work over the next five years with an agronomic goal in mind.
“By understanding these processes, either the mechanisms underlying them or specific variants that affect them, we can design ways to edit plant genomes and tweak these processes to serve agronomic goals,” Blackman says. “Or, using the variation that we identified in nature from our mapping populations, we can isolate markers for breeders to use to increase self-pollination efficiency.”
The sunflower seed production industry invests approximately $110,000,000 a year to rent honey bee hives and pollinators for their plants to do hybrid seed production--a process where pollinators take pollen from one plant and use it to fertilize another. However, this method of pollination is quickly becoming inefficient. With increasing costs and research proving the ineffectiveness of just using commercial bees, the work conducted by Ben Blackman and his collaborators could help make sunflower, and possibly lettuce, production more efficient and more cost effective.
If you’re an undergraduate interested in working on this project, click here to apply!