Submitted to: Plant and Soil
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/20/2005
Publication Date: 5/15/2006
Citation: Mano, Y., Omori, F., Takamizo, T., Kindiger, B.K., Bird, R., Loaisiga, C. 2006. Variation for root aerenchyma formation in flooded and non-flooded maize and teosinte seedlings. Plant and Soil Journal. 281:269-279. Interpretive Summary: Periods of periodic flooding typically result in reduced plant growth and production among most cereal and grass species. The presence of aerenchyma cells in developing root systems has been suggested to confer flooding tolerance in several grass species; however, no study has been undertaken to assess the degree and inducement of aerenchyma formation in these species. In this study, maize and one of its distant relatives were evaluated in two experiments for the presence of aerenchyma and their response to flooding conditions. Results of the first experiment indicate that after a period of flooding, both maize and teosinte seedlings formed aerenchyma. In addition, the degree of aerenchyma formation in the three genotypes increased during a second week of flooding suggesting aerenchyma formation is a response to flooding conditions. In a second experiment the expression of aerenchyma was determined to be genetically heritable and that its expression is variable among teosintes and maize inbred lines. These results indicate that aerenchyma formation can be transferred between lines of maize and its distant relative teosinte. Overall, the research indicates that selection for aerenchyma formation during a breeding and or selection program can result in the development of cultivars with tolerance to flooding. Results of this study may be applicable to the development of flooding tolerant cultivars of wheat, oats, sorghum and a variety of forage grasses.
Technical Abstract: Morphological and anatomical factors such as aerenchyma formation in roots and the development of adventitious roots are considered to be among the most important developmental characteristics affecting flooding tolerance. In this study, we investigated the lengths of adventitious roots and their capacity to form aerenchyma in three- and four-week-old seedlings of two maize (Zea mays ssp. mays) inbred accessions, B64 and Na4, and one teosinte, Z. nicaraguensis, with and without a flooding treatment. Three weeks after sowing and following a seven day flooding treatment, both maize and teosinte seedlings formed aerenchyma in the cortex of the adventitious roots of the first three nodes. The degree of aerenchyma formation in the three genotypes increased with a second week of flooding treatment. In the non-flooded treatment, the two maize accessions failed to form aerenchyma. In Z. nicaraguensis, aerenchyma developed in roots located at the first two nodes three weeks after sowing. In the fourth week, aerenchyma developed in roots of the third node, with a subsequent increase in aerenchyma in the second node roots. In a second experiment, we investigated the capacity of aerenchyma to develop in non-flooded treatments. Three teosinte species and 15 maize inbred lines, among them a set of flooding-tolerant maize lines, were evaluated. Evaluations indicate that accessions of Z. luxurians and two maize inbreds, B55 and Mo20W, form aerenchyma when not flooded. These materials may be useful genetic resources for the development of flooding-tolerant maize accessions.