Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/1/2005
Publication Date: 7/1/2005
Citation: Krakowsky, M.D., Lee, M., Coors, J.G. 2005. Quantitative trait loci for cell wall components in recombinant inbred lines of maize (Zea mays L.) I: stalk tissue. Journal of Theoretical and Applied Genetics. 111:337-346. Interpretive Summary: This research was conducted to improve our ability to alter fiber levels in the stalk of the maize plant. Maize forage is an important source of energy in animal production operations, but can be of limited use if the fiber content of the maize plant is too high and digestion of the material by animals is limited by high fiber content. Traditionally, maize breeders have focused on improving grain yield, and this can improve the digestibility of the whole plant since grain is easily digestible, but animals fed on forage with high grain content can suffer digestive problems due to the high levels of starch and simple sugars in the diet, and so it would better to improve the digestibility of the whole plant. We found a way to select for reduced fiber in maize that may be more efficient than methods currently used due to lower costs and increased simplicity. 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 levels of fiber in the stalk, which in turn will provide a more easily digestible and therefore more economically valuable source of feed to animal producers.
Technical Abstract: Maize silage is a significant energy source for animal production operations, and the efficiency of the conversion of forage into animal mass is an important consideration when selecting cultivars for use as feed. Fiber and lignin are negatively correlated with digestibility of feed, so development of forage with reduced levels of these cell wall components (CWCs) is desirable. While variability for fiber and lignin is present in maize germplasm, traditional selection has focused on the yield of the ear rather than the forage quality of whole plant, and little information is available concerning the genetics of fiber and lignin. The objectives of this study were to map quantitative trait loci (QTL) for fiber and lignin in the maize stalk and compare them with QTL from other populations. Stalk samples were harvested from 191 recombinant inbred lines (RILs) of B73 (low-intermediate levels of CWCs) x De811 (high levels of CWCs) 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 nine chromosomes, most in clusters in concordance with the high genetic correlations between NDF and ADF. Many of the QTL herein were also detected in studies using other populations, and most are linked to candidate genes for cellulose or starch biosynthesis. The genetic information obtained in this study should be useful to breeding efforts for improvement of the quality of maize silage.