A Purdue University researcher has taken corn off steroids and found that the results might lead to improvements in that and other crops.

Burkhard Schulz, an assistant professor of horticulture and landscape architecture, wanted to understand the relationship between natural brassinosteroids — a natural plant steroid hormone — and plant architecture, specifically plant height.

Schulz said corn could benefit by becoming shorter and sturdier, but the mechanisms that control those traits are not completely understood.

 "It is essential to change the architecture of plants to minimize how much land we need to produce food and fuels," said Schulz, whose findings are published in the early online version of the Proceedings of the National Academy of Sciences.

"If you can find a natural mutation or mechanism that gives you what you need, you are much better off than using transgenic techniques that could be difficult to get approval for.” 

Schulz found that when maize loses the ability to produce brassinosteroids, it becomes a dwarf, as he suspected. But another feature caught him off guard: The plants without the naturally occurring steroids could not make male organs — they had kernels where the tassels should be.

That could be a cost-saving discovery for the seed industry. Hybrid seed producers must painstakingly remove the male pollen-producing tassels from each plant so that they do not pollinate themselves. Schulz said maize plants that produce only female organs would eliminate the detasseling step.



"This would be the perfect mutation for hybrid seed production," Schulz said. "There is no way these plants could produce pollen because they do not have male flowers."



Schulz used a multi-step process to determine brassinosteroids' role in height and, later, sex determination. He wanted to ensure that light and the addition of gibberelic acid, a hormone that promotes cell growth and elongation, would not eliminate the dwarfism.



Schulz gathered known mutants of maize with short mesocotyls, the first node on a corn stalk. He suspected that even dwarf plants that produced brassinosteroids would have elongated mesocotyls if grown in the dark as they stretched for light, a trait typical of all brassinosteroid mutants.