Submitted to: Maydica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 6, 1997
Publication Date: N/A
Interpretive Summary: Eastern gamagrass (Tripsacum dactyloides) is known to thrive on soils that are periodically flooded. In a cooperative research effort between ARS scientists at Gainesville, FL and Woodward, OK, it was discovered that eastern gamagrass has a specialized root anatomy that includes large aerenchyma. Aerenchyma are air channels that allow the movement of oxygen from the top of the root down to the root tip. The aerenchyma are likely to be important in maintaining active eastern gamagrass roots under flooded conditions. The purpose of this study was to examine the presence of aerenchyma across 15 species in the Tripsacum genus. There was great diversity among the accessions examined for the presence of aerenchyma ranging from those with no aerenchyma to those with highly developed aerenchyma. This information is useful in identifying genetic resources for developing grasses for superior performance under flooded soil conditions.
Tripsacum plants of the species dactyloides (eastern gamagrass) have been observed to withstand flooded soil conditions and roots of this species have been observed to penetrate deep into heavy clay soils. One commonality between these conditions is the low oxygen environment surrounding the roots due to water logging or soil compression. In both cases, the presence of aerenchyma in T. dactyloides roots may have ameliorated the adverse impact of the low oxygen environment. Previously, we have found that some T. dactyloides accessions exhibit well-formed root aerenchyma even under well-aerated, non-stress environments which may allow a competitive advantage for this species in adapting to a wide range of habitats. In this survey of root anatomy, 15 of 16 species of Tripsacum were evaluated to determine the extent to which aerenchyma occur in a well-aerated, non-stress environment. Among the 15 species, 26 accessions were surveyed. In only five of the 15 species were large, well-formed aerenchyma found. This indicates that the ability to form aerenchyma under well-aerated, non-stress environments is not a universal adaptive mechanism within the genus and indicates the possibility of developing additional supraspecific groups based on root characteristics.