Target region amplification polymorphism (TRAP) is a fairly new PCR-based molecular marker technique which uses gene-based information for primer design. The objective of this study was to evaluate the utility of TRAP markers for assessing genetic diversity and interrelationships in sugarcane germplasm collections. Thirty genotypes from the genera Saccharum, Miscanthus, and Erianthus were used in the study. Among the genus Saccharum were the species, S. officinarum L., S. barberi Jesw., S. sinense Roxb., S. spontaneum L., S. robustum Brandes and Jeswiet ex Grassl, cultivars, cultivar-derived mutants and interspecific hybrids between S. officinarum and S. spontaneum. Six fixed primers, designed from sucrose-and cold tolerance-related EST (expressed sequence tags) sequences, paired with three arbitrary primers, were used to characterize the germplasm. Both the cluster and principal coordinate (PCoA) analyses placed the Erianthus spp. and Miscanthus spp. genotypes distinctly from each other and from the Saccharum species, thus, supporting their taxonomic classification as separate genera. Genotypes of the low sucrose and cold tolerant species, S. spontaneum, formed one distinct group, while the rest of the Saccharum species formed one interrelated cluster with no distinct subgroups. Sequence analysis of TRAP bands derived from a S. spontaneum genotype revealed homology with known gene sequences from other grass species including Sorghum. A BLASTn search using the homologous sequences from Sorghum matched with the S. officinarum GenBank accession from which the fixed TRAP primer was designed. These results ratify TRAP as a potentially useful marker technique for genetic diversity studies in sugarcane.

The tomato gene Mi-1 confers resistance to three species of root-knot nematodes, Meloidogyne spp. However, the resistance mediated by Mi-1 is inactive at soil temperatures above 28 degrees C. Previously, we identified and mapped a novel heat-stable nematode resistance gene from the wild species Lycopersicon peruvianum accession LA2157 on to chromosome 6. Here we report further characterization of this heat-stable resistance against three Mi-1-avirulent biotypes of Meloidogyne javanica, Meloidogyne arenaria and Meloidogyne incognita. Screening segregating F(2) and F(3) progenies, derived from an intraspecific cross between susceptible LA392 and resistant LA2157, for nematode resistance at 25 degrees C and 32 degrees C, revealed a simple dominant monogenic inheritance with all the biotypes tested. We designate this gene as Mi-9. As a first step towards cloning of Mi-9, we constructed a linkage map around this gene. A total of 216 F(2) progeny from the cross between LA392 and LA2157 were screened with M. javanica at 32 degrees C and with CT119 and Aps-1, markers that flank the genetic interval that contains the Mi-1 gene. DNA marker analysis indicated that these markers also flank Mi-9. Further mapping of recombinants with both RFLP and PCR-based markers localized Mi-9 to the short arm of chromosome 6 and within the same genetic interval that spans the Mi-1 region.

Registration of 'Oklee' Wheat relatively early maturing and produces spikes 1.3 d earlier 'Oklee' is a hard red spring wheat (Triticum aestivum L.) than 2375 and 0.6 d earlier than Oxen (PI 596770), the most (Reg. no. CV-963, PI 634553) developed and released by the widely grown cultivar in Minnesota since the late 1990s. Oklee Minnesota Agricultural Experiment Station in cooperation is a semidwarf cultivar and averages 75 cm, the same height with USDA-ARS in January 2003. It was named after a town as Oxen, and is 3 cm shorter than 2375 in Minnesota trials. in its region of adaptation in northwest Minnesota. Oklee was In 35 Minnesota trials conducted from 1998 through 2002, released on the basis of its high grain yield, high grain volume Oklee yielded 3664 kg ha Ϫ1 compared to 3482 kg ha Ϫ1 for weight, high grain protein content, and early maturity. In addi-2375 and 3825 kg ha Ϫ1 for Oxen. Oklee was evaluated in tion, Oklee has moderate resistance to Fusarium head blight 29 environments in the Uniform Regional Hard Red Spring (FHB, caused primarily by Fusarium graminearum Schwabe). Wheat Nursery in 1998 and 1999 and yielded an average of Oklee was derived from the cross '2375'/SBF0670, made 3456 kg ha Ϫ1 compared to an average of 3470 and 3503 kg by the former Pioneer Hi-Bred spring wheat breeding program ha Ϫ1 produced by the check cultivars, 2375 and Verde (PI in the USA. The cultivar 2375 (PI 601477, syn. Pioneer 2375) 592561, Busch et al., 1996), respectively. Oklee has moderately has the pedigree Olaf//Era/Suqamuxi 68/3/Chris/ND487//Lark strong straw and a lodging rating of 2.3 when scored on a and was widely grown in Minnesota during the mid-1990s due scale of 0 (erect) to 9 (lodged) in 21 environments at which to its moderate resistance to FHB. SBF0670 is an unreleased lodging occurred from 1998 thru 2002. By comparison, the line whose pedigree contains hard red spring lines once promicultivars 2375, Oxen, and Verde had lodging ratings of 3.5, nent in the region including 'Chris' (CItr 13751, Heiner and 2.6, and 2.1, respectively. Johnston, 1967), 'Era' (CItr 13986, Heiner and McVey, 1971), Oklee has moderate resistance to FHB in misted, inoculated and 'Butte'. field nurseries, similar to the resistance of 2375. In 11 FHB The F 2 population producing Oklee was selected for leaf nurseries from 1998 through 2001, Oklee averaged 23.6% disrust (caused by Puccinia triticina Eriks.) and stem rust (caused eased spikelets, 16.7% visually scabby kernels (VSK), and by Puccinia graminis Pers.: Pers.) resistance in a field planting 8.8 mg kg Ϫ1 of the mycotoxin deoxynivalenol (DON). The at St. Paul in 1993. The F 3 generation was advanced by single cultivar 2375 averaged 22.7% diseased spikelets, 17.5% VSK, seed descent in a greenhouse. The selection resulting in Oklee and 9.8 mg kg Ϫ1 DON. In the same trials, the resistant check was selected from a single plant in an F 4 headrow in 1994 and 'BacUp' (PI 596533, Busch et al., 1998) and the susceptible this seed was increased in a winter nursery in Arizona during check ...

Framework genetic linkage maps of two progenitor species of cultivated sugarcane, Saccharum officinarum 'La Striped' (2n = 80) and S. spontaneum 'SES 147B' (2n = 64) were constructed using amplified fragment length polymorphism (AFLP), sequence related amplified polymorphism (SRAP), and target region amplification polymorphism (TRAP) markers. The mapping population was comprised of 100 F 1 progeny derived from the interspecific cross. A total of 344 polymorphic markers were generated from the female (S. officinarum) parent, out of which 247 (72%) were single-dose (segregating in a 1:1 ratio) and 33 (9%) were double-dose (segregating in a 3.3:1 ratio) markers. Sixty-four (19%) markers deviated from Mendelian segregation ratios. In the S. spontaneum genome, out of a total of 306 markers, 221 (72%) were single-dose, 43 (14%) were double-dose, and 42 markers (14%) deviated from Mendelian segregation ratios. Linkage maps with Kosambi map distances were constructed using a LOD score C5.0 and a recombination threshold of 0.45. In Saccharum officinarum, 146 markers were linked to form 49 linkage groups (LG) spanning 1732 cM whereas, in S. spontaneum, 121 markers were linked to form 45 LG spanning 1491 cM. The estimated genome size of S. officinarum 'La Striped' was 2448 cM whereas that of S. spontaneum 'SES 147B' was 3232 cM. Based on the two maps, genome coverage was 69% in S. officinarum and 46% in S. spontaneum. The S. officinarum parent 'La Striped' behaved like an auto-allopolyploid whereas S. spontaneum 'SES 147B' behaved like a true autopolyploid. Although a large disparity exists between the two genomes, the existence of simple duplex markers, which are heterozygous in both parents and segregate 3:1 in the progeny, indicates that pairing and recombination can occur between the two genomes. The study also revealed that, compared with AFLP, the SRAP and TRAP markers appear less effective at generating a large number of genome-wide markers for linkage mapping in sugarcane. However, SRAP and TRAP markers can be useful for QTL mapping because of their ability to target gene-rich regions of the genome, which is a focus of our future research.

Resistance to Meloidogyne incognita (Kofoid and White) Chitwood in clones of Lycopersicon peruvianum (L.) Mill. PI 126443-1MH, 270435-2R2 and 2704353MH, their F1, a field-produced F2, and their test-cross (TC1) populations, was evaluated based on egg masses and eggs produced on root systems. Reactions to M. incognita isolates differing in virulence to gene Mi were determined at 25°C (Mi expressed) and 32°C (Mi not expressed). PI 126443-1MH, 270435-2R2, 270435-3MH, and their F1 progenies were resistant to Mi-virulent and Mi-avirulent isolates. At 32°C with a Mi-avirulent isolate and at 25°C with a Mi-virulent isolate, four TC1 generations segregated into resistant: susceptible (R∶S) ratios close to 3∶1. These results indicated resistance to Mi-(a)virulent M. incognita isolates is conferred by different non-allelic dominant genes in PI 126443-1MH, 270435-2R2 and 270435-3MH. The F2 progeny of PI 126443-1MH x EPP-1, challenged with Mi-avirulent M. incognita at 32°C and with Mi-virulent M. incognita at both 25°C and 32°C, segregated with a ratio of 3∶1 (R∶S), indicating expression of a single dominant resistance gene in PI 126443-1MH in each case. In dual screenings on clones of the same individual plants from the TC1 and F2 segregating populations, some individual plants were susceptible at 32°C to a Mi-avirulent isolate but resistant to the Mi-virulent isolate, and vice versa, suggesting that different but linked genes confer heat-stable resistance to Mi-avirulent M. incognita and resistance to Mi-virulent M. incognita. We propose the symbol Mi-5 for the gene in PI 126443 clone 1MH and the symbol Mi-6 for the gene in PI 270435 clone 3MH which both confer resistance to Mi-avirulent M. incognita isolates at high temperature. We propose the symbol Mi-7 for the gene in PI 270435 clone 3MH and the symbol Mi-8 for the gene in PI 270435 clone 2R2 that both confer resistance to the Mi-virulent M. incognita isolate 557R at moderate (25°C) temperature. The novel resistance genes are linked and reside in a genomic region in each parental clone that is independent from the Mi locus.