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Abstract

Using AFLP technology and a recombinant inbred line population derived from the sorghum cross of BTx623 x IS3620C, a high-density genetic map of the sorghum genome was constructed. The 1713 cM map encompassed 2926 loci distributed on ten linkage groups; 2454 of those loci are AFLP products generated from either the EcoRI/MseI or PstI/MseI enzyme combinations. Among the non-AFLP markers, 136 are SSRs previously mapped in sorghum, and 203 are cDNA and genomic clones from rice, barley, oat, and maize. This latter group of markers has been mapped in various grass species and, as such, can serve as reference markers in comparative mapping. Of the nearly 3000 markers mapped, 692 comprised a LOD >3.0 framework map on which the remaining markers were placed with lower resolution (LOD <3.0). By comparing the map positions of the common grass markers in all sorghum maps reported to date, it was determined that these reference markers were essentially collinear in all published maps. Some clustering of the EcoRI/MseI AFLP markers was observed, possibly in centromeric regions. In general, however, the AFLP markers filled most of the gaps left by the RFLP/SSR markers demonstrating that AFLP technology is effective in providing excellent genome coverage. A web site, http://SorghumGenome.tamu.edu, has been created to provide all the necessary information to facilitate the use of this map and the 2590 PCR-based markers. Finally, we discuss how the information contained in this map is being integrated into a sorghum physical map for map-based gene isolation, comparative genome analysis, and as a source of sequence-ready clones for genome sequencing projects.

Molecular mapping of Cg1, a gene for resistance to anthracnose (Colletotrichum sublineolum) in sorghum

“…Ninety-eight AFLP primer combinations, each with 3 base extensions (+3/+3) were initially examined in 12 resistant and 12 susceptible F 2:3 s along with the inbred parents BTx623 and SC748-5. Line IS3620C was also included so that both parents of a sorghum genomic map (BTx623 and IS3620C) could be compared for polymorphism and co-segregation in the susceptible/resistant F 2:3 s (Menz et al 2002). The products were examined using a dual-dye LI-COR 4200 IR 2 gel detection system (LI-COR Inc., Lincoln, NE).…”

“…The products were examined using a dual-dye LI-COR 4200 IR 2 gel detection system (LI-COR Inc., Lincoln, NE). Primer information and PCR conditions for all markers in this study were reported by Menz et al (2002) and can be viewed at the TAMU-USDA Sorghum Genome website (http:// sorgblast3.tamu.edu/).…”

“…SSR primer pairs derived from each of the 10 BAC clones were initially screened for the ability to detect polymorphisms in the parental lines, 12 resistant and 12 susceptible individuals by electrophoresis of the ampliWed products in 4% super Wne resolution (SFR) agarose (MidWest ScientiWc) gels. PCR conditions were as described in Menz et al (2002), with annealing temperatures ranging from 2°C above to 2°C below the T m of the primers. Only one of the 10 primer pairs, SSR Xtxp549, ampliWed polymorphic products in the parental lines.…”

Genetic Diversity Analysis of Eritrean Sorghum (<i>Sorghum bicolor</i> (L.) Moench) Germplasm using SSR Markers

“…A total of 29 labeled SSR markers previously described by Menz et al, (2002) were used for this study (Table 7). The preparation of PCR was done in 10 μl reaction volume consisting of 2 mM MgCl 2 , 1x PCR buffer, 0.20 μM reverse primer, 0.20 μM forward primer labeled with either 6 FAM, VIC, PET or NED, 0.04 mM of each of the four dNTPs and 0.2 U Taq DNA polymerase (Sibenzyme®), 30ng template DNA and topped up with sterile distilled water.…”

The Johne paradigm: From detection to management to treatment

“…Ever since the discovery of Mycobacterium avium subspecies paratuberculosis (MAP) as the etiologic agent of the granulomatous enteritis of ruminants known as Johne disease [1][2][3][4][5] in the early 1910s, and since the disease was first described in the US in 1908 by Leonard Pearson, the fight has waged on to find a reliable cure/treatment for MAP-infected cattle. This fight has been severely hindered by the extremely slow doubling time of the organism and unreliable diagnostic methods.…”