Comparative genome mapping of Sorghum bicolor (L.) Moench using an RFLP map constructed in a population of recombinant inbred lines

Abstract

A restriction fragment length polymorphism (RFLP) linkage map of Sorghum bicolor (L.) Moench was constructed in a population of 137 F6‐8 recombinant inbred lines using sorghum, maize, oat, barley and rice DNA clones. The map consists of 10 linkage groups (LGs) and 323 markers, 247 of which (76.5%) were ordered at a LOD score ≥ 3.0. The LGs comprise from 61 (LG A) to 13 markers (J), which range in length from 205 (A) to 55 cM (J) and have a combined total length of 1347 cM. Highly significant distorted segregation was detected at all of the 38 loci in a 103‐cM segment of LG A, the allelic ratios in the segment ranging from approximately 3:1 (one end) to 19:1 (middle) to 2:1 (other end). Duplicated loci located in different LGs have been mapped with 55 of the 295 DNA probes used in the study (18.6%). The distribution of these loci does not provide support for the hypothesis that Sorghum bicolor (L.) Moench is of tetraploid origin. Comparison of the map with RFLP maps of maize, rice, and oat produced evidence for sorghum‐maize LG rearrangements and homoeologies not reported previously, including evidence that: (1) a segment of maize 5L and a segment of 5S may be homoeologous to sorghum LGA; (2) maize LGs 4 and 6 are partly homoeologous to sorghum LGE; (3) the short arm of maize LG 2 is partly homoeologous to sorghum LGF; (4) maize LG 4 may be partly homoeologous to sorghum LG G; (5) maize LG 5 and sorghum LG G contain a larger amount of homoeologous genetic material than previously indicated; and (6) a short segment of maize LG 1 may be homoeologous to a short segment of sorghum LG I.

Targeted Analysis of Orthologous Phytochrome A Regions of the Sorghum, Maize, and Rice Genomes using Comparative Gene-Island Sequencing

“…Similar to others in the Poaceae family, early linkage studies established orthology in large segments of the maize and sorghum genomes, although numerous segmental duplications and deletions were noted (Hulbert et al, 1990;Binelli et al, 1992;Chen et al, 1997;Helentjaris et al, 1988;Peng et al, 1999). Genetic markers shared between rice and sorghum have been directly compared (Ventelon et al, 2001), and similar conclusions have been reached.…”

“…The likely colinear relationship between large portions of the maize and sorghum genomes coupled with the smaller genome size of sorghum makes comparative map-based cloning studies especially attractive and feasible for this species. Dense genetic maps have been established for sorghum (Whitkus et al, 1992;Melake-Berhan et al, 1993;Chittenden et al, 1994;Dufour et al, 1997;Boivin et al, 1999;Peng et al, 1999;Bhattramakki et al, 2000;Menz et al, 2002). These sorghum maps contain DNA markers common to maize and other grass genetic maps, making crossreferencing between these species possible.…”

The Blast Resistance Gene Pi37 Encodes a Nucleotide Binding Site–Leucine-Rich Repeat Protein and Is a Member of a Resistance Gene Cluster on Rice Chromosome 1

“…The Pi37 gene cluster contains four NBS-LRR genes, arranged in tandem in the same orientation. The complex shares substantial homology to the maize rp1 complex (Peng et al 1999;Ayliffe et al 2000). rp1 haplotypes vary in the number of homologs present, ranging from as few as 1 to as many as 50 (Monosi et al 2004).…”

Comparative Sequence Analysis of the Sorghum RphRegion and the Maize Rp1 Resistance Gene Complex

“…Because the sequenced genes are highly homologous to the Rp1 genes of maize and because they map on sorghum linkage group H at a syntenic position with the short arm of maize chromosome 10 where Rp1 is found (Peng et al, 1999), we have named these genes rph1-1 through rph1-5 (Fig. 2).…”