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Quantitative trait loci (QTLS) for grain quality, yield components and other traits were investigated in two Sorghum caudatum x guinea recombinant inbred line (RIL) populations. A total of 16 traits were evaluated (plant height, panicle length, panicle compactness, number of kernels/panicle, thousand-kernel weight, kernel weight/panicle, threshing percentage, dehulling yield, kernel flouriness, kernel friability, kernel hardness, amylose content, protein content, lipid content, germination rate and molds during germination and after harvest) and related to two 113- and 100 point base genetic maps using simple (SIM) and composite (CIM) interval mapping. The number, effects and relative position of QTLs detected in both populations were generally in agreement with the distributions, heritabilities and correlations among traits. Several chromosomal segments markedly affected multiple traits and were suspected of harbouring major genes. The positions of these QTLs are discussed in relation to previously reported studies on sorghum and other grasses. Many QTLS, depending on their relative effects and position, could be used as targets for marker-assisted selection and provide an opportunity for accelerating breeding programmes.

Comparative mapping within maize, sorghum and sugarcane has previously revealed the existence of syntenic regions between the crops. In the present study, mapping on the sorghum genome of a set of probes previously located on the maize and sugarcane maps allow a detailed analysis of the relationship between maize chromosomes 3 and 8 and sorghum and sugarcane homoeologous regions. Of 49 loci revealed by 46 (4 sugarcane and 42 maize) polymorphic probes in sorghum, 42 were linked and were assigned to linkage groups G (28), E (10) and I (4). On the basis of common probes, a complete co-linearity is observed between sorghum linkage group G and the two sugarcane linkage groups II and III. The comparison between the consensus sorghum/sugarcane map (G/II/III) and the maps of maize chromosomes 3 and 8 reveals a series of linkage blocks within which gene orders are conserved. These blocks are interspersed with non-homoeologous regions corresponding to the central part of the two maize chromosomes and have been reshuffled, resulting in several inversions in maize compared to sorghum and sugarcane. The results emphasize the fact that duplication will considerably complicate precise comparative mapping at the whole genome scale between maize and other Poaceae.