A Purdue University study confirms complex associations among plant hormones and their signaling pathways that are key to controlling plant architecture.

Plant architecture is partly controlled through the production and perception of plant hormones. The loss of either the brassinosteroid or gibberellin plant hormones results in dwarfed plants. Removing both can increase this effect, which suggested that they control plant growth separately.

That's important for scientists who want to understand how plants modify their architecture to compete for resources or create higher-yielding crops, like corn. Creating dwarf varieties of the crop plant could increase yield or keep yield steady while reducing the required inputs such as fertilizers and water.

Dwarf varieties of rice and wheat were made by essentially inhibiting the response to some hormones. But in corn, the interplay among hormones makes this more complicated.

Brassinosteroids and gibberellins are involved in more characteristics than just plant height in maize. Brassinosteroids, for example, are required for the tassels to contain flowers that produce pollen, and gibberellins are required for ears to only produce ovules.

An associate professor of biochemistry, Brian Dilkes said, "Plant cells use these hormones to communicate with each other to control development in a coordinated manner. These processes determine form and execute the correct cellular programs at the correct times. We will not be able to manipulate crop architecture for a particular goal if we don't understand how moving one part causes another part to change. These are highly interactive systems, and the different cellular circuits impinge on one another."

In a previous study, Dilkes and collaborators investigated the genetic interactions between the genes that encode proteins that help synthesize these two hormones in maize. Maize mutants that lacked either brassinosteroids or gibberellins were interbred.

Combining these mutants masked some of the physical characteristics of the parent mutants, demonstrating that the two hormones were mutually dependent in the control of branching and tassel development.

Source: https://www.purdue.edu/