LAUSR

Molecular breeding is capable of improving important agricultural crop traits by controlling functional genes, aiming to attain high yield, stability and quality. During this process, the quantity and maneuverability of functional genes are important in determining breeding efficiency. In our research, 186 functional genes relating to maize agronomic traits, which are available for marker-assisted selection or genetic transformation strategies, were collected from the literature and projected onto an integration map. The traits corresponding to these functional genes included disease resistance, stress tolerance, tassel traits, ear traits, kernel-related traits, leaf traits and plant-type characteristics. The integration map demonstrated that these functional genes were unevenly distributed on maize chromosomes. The greatest and fewest numbers of functional genes were found on chromosomes 1 and 8, respectively. Moreover, 36, 25, 27, 23, 14, 15, 11, 6, 9 and 20 genes were found on chromosomes 1 to 10, respectively. Most of disease-resistant genes were found on chromosome 10, while the genes of kernel-related and leaf-related traits were found on chromosomes 4 and 2, respectively. Out of the 186 functional genes, 95 have been characterized using genetic mapping, 19 using map-based cloning, 53 using transposon-tagging cloning strategies and 19 using other methods. Thus, the number of functional genes identified in maize is still limited and further research on functional genes is required.