Plants grown in high-density or crowded populations often put more energy into growth and maintenance than reproduction. For example, flowering may be delayed as plants allocate¹ resources to growing taller and escape competition for light. This sensitivity to crowding stress has been observed in some varieties of sweet corn, but other varieties show higher tolerance², producing high yields even in crowded conditions. A recent University of Illinois and USDA Agricultural Research Service study attempted to uncover the genetic⁴ mechanisms⁵ of crowding tolerance in sweet corn. "We were trying to find genes⁶ that differentiate⁷ sweet corn hybrids⁹ that have potential to produce higher yields under crowding stress versus¹⁰ hybrids with lower yields under the same growing conditions," explains U of I crop science researcher Eunsoo Choe. 

 

Choe and her team measured observable or phenotypic traits for high- and low-yielding hybrids under crowding stress; these included traits known to correlate with crowding stress, such as plant height, leaf area, and time to maturity¹¹. Other traits, such as yield, kernel¹² mass, kernel moisture, and fill percentage were also measured. Lastly, the team extracted genetic material from the plants to explore correlations¹³ between gene³ expression patterns and measured traits.

 

"We found clusters of genes that were related to yield under crowding stress," says Choe. 

 

Although gene expression patterns indicated each hybrid⁸ utilized¹⁴ unique mechanisms for tolerating crowding stress, the researchers did confirm a common genetic basis for the yield response in the six hybrids tested. Low-yielding hybrids had gene activities related to various stress responses while high-yielding hybrids utilized gene activities more directly related to carbohydrate¹⁵ accumulation.

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