cTnI was superior to CK-MB for detection of myocyte injury in myocarditis, and cTnI elevations were substantially more common in the first month after the onset of heart failure symptoms.

Among maize (Zea maize L.) breeders, there is a heightened awareness of the necessity for both maintaining genetic diversity for crop improvement and improving the quality of genetic resource management. Restriction fragment length polymorphisms (RFLPs) and isozymes can serve as genetic markers for estimating divergence or diversity; however, the limited number of polymorphic isozyme loci available and the labor intensive and time consuming nature of RFLPs make their use for this purpose prohibitive. Simple sequence repeats (SSRs), when resolved using agarose gels, may be a viable and costeffective alternative to RFLPs and isozymes. Ninety‐four elite maize inbred lines, representative of the genetic diversity among lines derived from the Corn Belt Dent and Southern Dent maize races, were assayed for polymorphism at 70 SSR marker loci using agarose gels. The 365 alleles identified served as raw data for estimating genetic similarities among these lines. The patterns of genetic divergence revealed by the SSR polymorphisms were consistent with known pedigrees. A cluster analysis placed the inbred lines in nine clusters that correspond to major heterotic groups or market classes for North American maize. A unique fingerprint for each inbred line could be obtained from as few as five SSR loci. The utility of polymerase chain reaction (PCR)‐based markers such as SSRs for measuring genetic diversity, for assigning lines to heterotic groups and for genetic fingerprinting equals or exceeds that of RFLP markers, a property that may prove a valuable asset for a maize breeding program.

Simple sequence repeats (SSRs), also known as microsatellites, are highly variable DNA sequences that can be used as markers for the genetic analysis of plants. Three approaches were followed for the development of PCR primers for the amplification of DNA fragments containing SSRs from sorghum [Sorghum bicolor (L.) Moench]: a search for sorghum SSRs in public DNA databases; the use of SSR-specific primers developed in the Poaceae species maize (Zea mays L.) and seashore paspalum grass (Paspalum vaginatum Swartz); and the screening of sorghum genomic libraries by hybridization with SSR oligonucleotides. A total of 49 sorghum SSR-specific PCR primer pairs (two designed from GenBank SSR-containing sequences and 47 from the sequences of genomic clones) were screened on a panel of 17 sorghum and one maize accession. Ten primer pairs from paspalum and 90 from maize were also screened for polymorphism in sorghum. Length polymorphisms among amplification products were detected with 15 of these primer pairs, yielding diversity values ranging from 0.2 to 0.8 with an average diversity of 0.56. These primer pairs are now available for use as markers in crop improvement and conservation efforts.

No abstract

Simple sequence repeats (SSRs) are rapidly becoming an important class of DNA markers that are being widely used to map both plant and animal genomes. SSRs have the advantage of providing a codominant marker system based on polymerase chain reaction (PCR) methodology. Although the presence of SSRs is now well documented in the plant kingdom, a mapped set of primer sequences in maize (Zea mays L.) is not available. Polymorphic primer pairs developed from maize sequences in GENBANK were mapped to 42 loci in maize by means of either a B73 × Mo17, Mo17 × H99, or B73 × G35 recombinant inbred population. All SSR loci were found to be linked to one or more adjacent restriction fragment length polymorphism (RFLP) and/or isozyme loci. Segregation followed a pattern of Mendelian inheritance with one SSR locus deviating from expected ratios at a 1% level of significance. The SSRs were distributed throughout the maize genome with no evidence of clustering. Each SSR marker detected a single locus.

indicated that genetic improvement usually accounted for about one-half of the total yield increase, with the This paper was presented as part of the symposium entitled "Postremainder attributed to changes in cultural practices

A random set of recombinant inbred (RI) lines (F2:7) derived from the cross of the inbred lines Mo17 (resistant) and B73 (susceptible) were evaluated for resistance to southern leaf blight (SLB) caused by Cochliobolus heterostrophus race O. The RI lines were genotyped at a total of 234 simple sequence repeat, restriction fragment length polymorphism, or isozyme loci. Field plots of the RI lines were inoculated artificially with an aggressive isolate of C. heterostrophus race O in each of two growing seasons in North Carolina. Lines were rated for percent SLB severity two (1996) or three (1995) times during the grain-filling period. Data also were converted to area under the disease progress curve (AUDPC) and analyzed using the composite interval mapping option of the PLABQTL program. When means of disease ratings over years were fitted to models, a total of 11 quantitative trait loci (QTLs) were found to condition resistance to SLB, depending upon which disease ratings were used in the analyses. When the AUDPC data were combined and analyzed over environments, seven QTLs, on chromosomes 1, 2, 3, 4, 7, and 10 were found to come from the resistant parent Mo17. An additional QTL for resistance on chromosome 1 came from the susceptible parent B73. The eight identified QTLs accounted for 46% of the phenotypic variation for resistance. QTL x environment interactions often were highly significant but, with one exception, were the result of differences in the magnitude of QTL effects between years and not due to changes in direction of effects. QTLs on the long arm of chromosome 1 and chromosomes 2 and 3 had the largest effects, were the most consistently detected, and accounted for most of the phenotypic variance. No significant additive x additive epistatic effects were detected. These data support earlier reports of the polygenic inheritance of resistance to SLB of maize.

Information regarding genotypic variability for maize (Zea mays L.) grain‐filling patterns is scarce, especially at the inbred level. We characterized a large set of public and elite proprietary inbred lines for kernel growth traits. Lines were selected to sample divergent kernel size, genetic diversity, and lines released from breeding programs. The traits characterized were final kernel weight (KW), kernel growth rate (KGR), grain‐filling duration (GFD), maximum water content and moisture concentration (fresh weight basis) at physiological maturity. We evaluated 32 inbred lines in 2006 and 35 inbred lines in 2007. Kernel weight ranged from 104 to 317 mg per kernel in 2006 and from 96 to 327 mg per kernel in 2007. Variation in KW was achieved through different combinations of KGR (0.14 to 0.44 mg °Cd−1 kernel−1) and GFD (610 to 1137 °Cd). There was no correlation between KGR and GFD. Moisture concentration at physiological maturity showed significant genotypic differences (p < 0.001), ranging from 280 to 600 g kg−1 A previously described framework for predicting kernel growth patterns based on kernel water accumulation was tested for accuracy and differences were observed (p < 0.01), suggesting that a general pattern cannot be used to describe all the genotypic variability available. Results demonstrate the high variability in KW across elite and public maize inbreds, reflecting a wide range of KGRs and GFDs.