phisms among 36 sorghum lines were equally low for profiles obtained by means of 30 RAPD primers or 29 DNA markers are being increasingly utilized in cultivar develop- RFLP probes. Vierling et al. (1994) found 73 RAPD ment, quality control of seed production, measurement of genetic diversity for conservation management, varietal identity, and to assist primers discriminated among sorghum lines but those in maintenance of intellectual property protection (IPP). The use of data did not allow lines to be associated into groupings simple sequence repeats (SSRs) for variety profiling can provide high that reflected pedigrees. Associations among 34 lines discrimination, with excellent reproducibility at less cost than for determined by 19 RFLP probes, 21 RAPD primers, and restriction fragment length polymorphisms (RFLPs). The objective 41 ISSRs were markedly different and dependent on of this study was to evaluate the potential utility of SSR technology the source of molecular profile data (Yang et al., 1996). for applications in research, product development, seed production, Ahnert et al. (1996) reported a study of 105 sorghum and genetic resource conservation management for sorghum. Fifty inbreds that used 104 RFLP probes which showed genetically diverse elite sorghum [Sorghum bicolor (L.) Moench]higher levels of polymorphism and associations of lines inbreds were used to compare the discrimination abilities of 15 SSR that were congruent with pedigree information and primers with 104 RFLPs and to compare the associations among lines revealed by these molecular data and by pedigrees. RFLP data allowed

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Oat (Avena sativa L.) genotypes differ in their patterns of growth and development in response to vernalization (cold temperatures applied to germinating seeds). Genomic regions controlling vernalization response in heading date, plant height, and tiller number were mapped in a recombinant inbred (RI) population derived from the cross of oat cultivars ‘Kanota’ (vernalization‐responsive) and ‘Ogle’ (vernalization‐insensitive).Seventy‐one F6‐derived RI lines were subjected to vernalization and no‐vernalization treatments, and then grown in growth chambers. A genetic linkage map of 561 (primarily RFLP) loci was used to identify quantitativet rait loci (QTLs) affecting the traits in vernalized and non‐vernalized plants. Nine to 16 linkage groups and unlinked loci were associated with each trait assessed herein. Individual loci explained up to 37% of the phenotypic variation. Three to five significant loci were included in multiple locus linear models which explained up to 66% of phenotypic variation for each trait. One to 14 interactions between loci were found for each trait. The interactions explained up to 30% of the phenotypic variation not accounted for by the main effects of loci involved in the interactions. Inclusion of epistatic interactions tended to improve the fit of multiple locus models. As much as 83% of phenotypic variation was explained by multiple locus models including epistasis. Numerous epistatic interactions involving at least one locus with no significant main effect were detected.

A detailed linkage map of Helianthus annuus was constructed based on segregation at 234 RFLP loci, detected by 213 probes, in an F2 population of 289 individuals (derived from a cross between the inbred lines HA89 and ZENB8). The genetic markers covered 1380 centiMorgans (cM) of the sunflower genome and were aranged in 17 linkage groups, corresponding to the haploid number of chromosomes in this species. One locus was found to be unlinked. Although the average interval size was 5.9 cM, there were a number of regions larger than 20 cM that were devoid of markers. Genotypic classes at 23 loci deviated significantly from the expected ratios (1∶2∶1 or 3∶1), all showing a reduction in the ZENB8 homozygous class. The majority of these loci were found to map to four regions on linkage groups G, L and P.

The starch from eight ethyl methanesulfonate (EMS) treated M4 families of the corn (Zea mays L.) inbred line B73 was analyzed using differential scanning calorimetry (DSC), a Rapid Visco Analyser (RVA), a texture analyzer (TA), and scanning electron microscopy (SEM) coupled with image analysis. The eight families were chosen from 144 families previously selected for having starch with unusual DSC parameters. Apparent amylose contents of the starch from the eight families generally were lower than that of the control. According to DSC, starches from mutagenized families tended to have lower onset temperature (T 0 ) of gelatinization, enthalpy (ΔH) of gelatinization, and peak height index (PHI), but broader gelatinization range (R) than the B73 control. Their values for ΔH and percentage of retrograzdation (%R) were clustered around that of the control. Pasting properties from the RVA of the starches from the M4 families also were clustered around those of the control B73 starch, except for the setback values which were lower than B73 for M4 starches. Gel firmness values, as measured by TA, of all the M4 starches were generally lower than that of the B73 starch at storage treatments of one day at 25°C or seven days at 4°C. The stickiness of the gels of the M4 starches tended to be greater than that of B73 after seven days of storage at 4°C. These observations were consistent with the lower apparent amylose values for the M4 starches. SEM and image analysis data revealed no differences among the treatments in granule size and shape. Possibly, EMS treatment altered the genes, affecting internal structure of the starch granules. Starch from the mutagenized families likely had lower bonding forces among molecules and fewer long chains in the amylopectin molecules than did B73. RightsWorks produced by employee of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. The starch from eight ethyl methanesulfonate (EMS) treated M4 families of the corn (Zea mays L.) inbred line B73 was analyzed using differential scanning calorimetry (DSC), a Rapid Visco Analyser (RVA), a texture analyzer (TA), and scanning electron microscopy (SEM) coupled with image analysis. The eight families were chosen from 144 families previously selected for having starch with unusual DSC parameters. Apparent amylose contents of the starch from the eight families generally were lower than that of the control. According to DSC, starches from mutagenized families tended to have lower onset temperature (T o ) of gelatinization, enthalpy (∆H) of gelatinization, and peak height index (PHI), but broader gelatinization range (R) than the B73 control. Their values for ∆H and percentage of retrograzdation (%R) were clustered around that of the control. Pasting properties from the RVA of the starches from the M4

No abstract

Maize silage is a significant energy source for animal production operations, and the efficiency of the conversion of forage into animal mass is an important consideration when selecting cultivars for use as feed. Fiber and lignin are negatively correlated with digestibility of feed, so the development of forage with reduced levels of these cell-wall components (CWCs) is desirable. While variability for fiber and lignin is present in maize germplasm, traditional selection has focused on the yield of the ear rather than the forage quality of the whole plant, and little information is available concerning the genetics of fiber and lignin. The objectives of this study were to map quantitative trait loci (QTLs) for fiber and lignin in the maize stalk and compare them with QTLs from other populations. Stalk samples were harvested from 191 recombinant inbred lines (RILs) of B73 (an inbred line with low-to-intermediate levels of CWCs) x De811 (an inbred line with high levels of CWCs) at two locations in 1998 and one in 1999 and assayed for neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL). The QTLs were detected on nine chromosomes, mostly clustered in concordance with the high genetic correlations between NDF and ADF. Adjustment of NDF for ADF and ADF for ADL revealed that most of the variability for CWCs in this population is in ADF. Many of the QTLs detected in this study have also been detected in other populations, and several are linked to candidate genes for cellulose or starch biosynthesis. The genetic information obtained in this study should be useful to breeding efforts aimed at improving the quality of maize silage.

The objective of this study was to use restriction fragment length polymorphisms (RFLPs) to determine the genetic location and effects of genomic regions controlling plant height in sorghum. F2 plants (152) from the cross CK60 x PI229828 were used. Genomic and cDNA clones (106) identified 111 loci distributed among ten linkage groups covering 1299 cM. Interval mapping identified four regions, each in a separate linkage group. These regions may correspond to loci (dw) previously identified by alleles with qualitative effects. Also, these regions identified in sorghum may be orthologous to those previously reported for plant height in maize. Gene effects and gene action varied among genomic regions. In each region, PI229828 alleles resulted in increased plant height. Each region accounted for 9.2-28.7% of the phenotypic variation. Positive, additive effects ranged from 15 to 32cm. Tallness was dominant or overdominant and conferred by alleles from PI229828 for three quantitative trait loci (QTL). At the fourth QTL, PI229828 contributed to increased plant height, but short stature was partially dominant. One digenic interaction was significant. The presence of a PI229828 allele at one region diminished the effects of the other region. A multiple model indicated that these four regions collectively accounted for 63.4% of the total phenotypic variation. The utility of this information for germplasm conversion through backcross breeding is discussed.