Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/30/2005
Publication Date: 1/15/2006
Citation: Krakowsky, M.D., Lee, M., Coors, J.G. 2006. Quantitative trait loci for cell wall components in recombinant inbred lines of maize (Zea mays l.) II: leaf sheath tissue. Theoretical and Applied Genetics. 112:717-726. Interpretive Summary: This research was conducted to improve our ability to alter fiber levels in maize plants. Maize forage is an important source of energy in animal production operations, but can be of limited use if the fiber content is too high and digestion of the material by animals is limited. We examined a method for selecting for reduced fiber in maize that may be more efficient than methods currently used due to lower costs and increased simplicity. We found that fiber in the stalk is not highly correlated with fiber in the leaf sheath, thereby making it necessary to analyze plant tissues individually rather than on a whole-plant basis. We also have a better idea of what factors influence fiber levels in the maize stalk and this information can be used for further studies on changing fiber and the consequences of such changes. The results of this experiment are important because they can allow scientists to select maize plants with reduced fiber levels, which in turn will provide a more easily digestible and therefore more economically valuable source of feed to animal producers.
Technical Abstract: While maize silage is a significant feed component in animal production operations, little information is available on the genetic bases of fiber and lignin concentrations in maize, which are negatively correlated with digestibility. Variability for these traits in maize germplasm has been reported, but the sources of the variation and the relationships between these traits in different tissues are not well understood. In this study, 191 recombinant inbred lines of B73 (low-intermediate levels of cell wall components (CWCs)) x De811 (high levels of CWCs) were analyzed for quantitative trait loci (QTL) associated with CWCs in the leaf sheath. Samples were harvested from plots at two locations in 1998 and one in 1999 and assayed for neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL). QTL were detected on all ten chromosomes, most in tissue specific clusters in concordance with the high genetic correlations for CWCs within the same tissue. Adjustment of NDF for its subfraction, ADF, revealed that most of the genetic variation in NDF was probably due to variation in ADF. The low to moderate genetic correlations for the same CWC across tissues indicate that some genes for CWCs may only be expressed in certain tissues. Many of the QTL herein were detected in other populations, and some are linked to candidate genes for cell wall carbohydrate biosynthesis. The genetic information obtained in this study should be useful for efforts to improve the quality of maize forage.