Experimental Design and Statistical Analysis:
Bt Corn, Lignin, and ANOVAs

Part I—"Abstract"

by
Eric Ribbens
Department of Biological Sciences
Western Illinois University
European corn borer

This case is based on a recent publication by Saxena and Stotzky entitled "Bt Corn Has a Higher Lignin Content Than Non-Bt Corn" in the American Journal of Botany (Sept. 2001, vol. 88, no. 9, pp.1704-1706).

Read the abstract of their paper:

"Bt corn has been genetically modified to express the Cry1Ab protein of Bacillus thuringiensis to kill lepidopteran pests.  Fluorescence microscopy and staining with toluidine blue indicated a higher content of lignin in the vascular bundle sheaths and in the sclerenchyma cells surrounding the vascular bundle in all ten Bt corn hybrids, representing three different transformation events, studied than of their respective non-Bt isolines. Chemical analysis confirmed that the lignin content of all hybrids of Bt corn, whether grown in a plant growth room or in the field, was significantly higher (33-97% higher) than that of their respective non-Bt isolines.  As lignin is a major structural component of plant cells, modifications in lignin content may have ecological implications."

Questions:

  1. What does the Bt in Bt-corn represent and why was it used to genetically modify corn plants?
  2. What is lignin?  Why is it an important plant chemical?
  3. What was their research question?
  4. Based on the abstract above, reconstruct their experimental approach.  What did they do?  How did they do it?  What did they compare, and how do those comparisons help them answer their research question?
  5. What questions do you have about their research protocol that the abstract does not answer?


Go to Part II—"Methods"


Image Credit:  European corn borer, Ostrinia nubilalis, an insect species introduced to North America and belonging to the family Pyralidae in the order Lepidoptera.  Photo by Keith Weller, from the collection of the USDA Agricultural Research Service.

Date Posted:  10/03/02 nas
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