Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2006
Publication Date: 11/1/2006
Citation: Horvath, D.P., Gulden, R., Clay, S.A. 2006. Microarray analysis of late- season velvetleaf (Abutilon theophrasti) effect on corn. Weed Science. 54:983-994. Interpretive Summary: There are various ideas about how weeds cause yield losses in plants. There is also some evidence to suggest that weeds such as velvetleaf only have an impact on corn during early stages of growth. We have used a technique called microarray analysis that allows us to determine differences in genes that are turned on or off in plots of corn that were either infested with velvetleaf or was free of velvet leaf. We chose a point in development where the corn was about 30-50 cm taller than the velvetleaf. This is a time when the velvetleaf was suspected of having little effect on the growing corn. We found that most genes showed little or no changes in expression in response to velvetleaf infestations. However there were some significant differences in a few genes that are involved in cell division, photosynthesis, protein accumulation/degradation, and signaling responses of the plant hormones auxin and ethylene. Thus, we have demonstrated that we can use microarray technology to study the physiological impact of velvetleaf on corn, and that this weed does impact several important physiological processes that could affect yield even after the corn has overtopped the weed.
Technical Abstract: Microarray analysis was used to identify changes in gene expression in corn leaves collected from plants at the V11-14 growth stage that resulted from competition with velvetleaf. The plants were grown in field plots under adequate N (addition of 220 kg N ha-1) and irrigation to minimize N and water stress. Consequently only differences due to competition for micronutrients, light and perhaps allelopathic stress were anticipated. Genes involved in carbon and nitrogen utilization, photosynthesis, growth and development, oxidative stress, signal transduction, responses to auxin and ethylene, and zinc transport were repressed in corn growing in competition with velvetleaf. Very few genes were induced due to competition with velvetleaf, and those that were provided little indication of the physiological response of corn. No differences were observed in multiple genes responsive to water stress or sequestering/transporting most micronutrients indicating that these stresses were not a major component of velvetleaf competition with corn at the developmental stage tested.