Improvement of end‐use quality in wheat (Triticum aestivum L.) depends on thorough understanding of the influences of environment, genotype, and their interaction. Our objectives were to determine relative contributions of genotype, environment, and G × E interaction to variation in quality characteristics of hard red winter wheat. Eighteen winter wheat genotypes were grown in replicated trials at six locations in Nebraska and one site in Arizona in 1988 and 1989. Harvested grain was micromilled to produce flour samples for evaluation of protein concentration, mixing characteristics, and sodium dodecylsulfate (SDS) sedimentation. Kernel hardness was determined by microscopic evaluation of individual kernels. Genotype, environment, and interaction effects were found to significantly influence variation in all quality parameters. Variances of quality characteristics associated with environmental effects were generally larger than those for genetic factors. The magnitude of G × E effects were found to be of similar magnitude to genetic factors for mixing tolerance and kernel hardness, but were smaller for flour protein concentration, mixing time, and SDS sedimentation value. Significant differences among genotype responses (b‐values) were observed in the regressions of genotype mean on location means for each quality parameter. There were few instances of significant deviations from regression. Positive correlations between genotype grand mean and genotype b‐values for flour protein, mixing time, and mixing tolerance suggest that simultaneous improvement in both mean and stability for these traits may be difficult. Based on these results, environmental influences on enduse quality attributes should be an important consideration in cultivar improvement efforts toward enhancing marketing quality of hard red winter wheat.

Data from USDA‐coordinated winter wheat (Triticum aestivum L.) regional performance nurseries collected over the time period 1959 to 2008 were used to estimate genetic gain (loss) in grain yield, grain volume weight, days to heading, and plant height in winter wheats adapted to the Great Plains of North America. In both the Southern Regional (SRPN) and Northern Regional Performance Nurseries (NRPN), linear regression revealed significant positive relationships between relative grain yields of advanced breeding lines and calendar year of the nursery trial. The estimated genetic gain in grain yield potential since 1959 was approximately 1.1% (of the control cultivar Kharkof) yr−1 for all entries in the SRPN, and 1.3% yr−1 if only the most productive entry was considered. For the NRPN, the estimates of genetic gain in grain yield were 0.79% yr−1 for all entries, and also 0.79% yr−1 for the most productive entry. Linear regressions of relative grain yields vs. year over the time period 1984 to 2008, however, showed no statistically significant trend in the SRPN. For the same time period in the NRPN, a statistically significant positive slope of 0.83 was observed, though the coefficient of determination (R2) was only 0.28. Relative grain yields of Great Plains hard winter wheats may have peaked in the early to mid‐1990s, and further improvement in the genetic potential for grain yield awaits some new technological or biological advance.

Virulence of the human malaria parasite Plasmodium falciparum is believed to relate to adhesion of parasitized erythrocytes to postcapillary venular endotheium (asexual cytoadherence). Transmission of malaria to the mosquito vector involves a switch from asexual to sexual development (gametocytogenesis). Continuous in vitro culture of P.fakiparum frequently results in irreversible loss of asexual cytoadherence and gametocytogenesis. Field isolates and cloned lines differing in expression of these phenotypes were karyotyped by pulse-field gel electrophoresis. This analysis showed that expression of both phenotypes mapped to a 0.3-Mb subtelomeric deletion of chromosome 9. This deletion frequently occurs during adaptation of parasite isolates to in vitro culture. Parasites with this deletion did not express the variant surface agglutination phenotype and the putative asexual cytoadherence ligand designated P. fakiparum erythrocyte membrane protein 1, which has recently been shown to undergo antigenic variation. The syntenic relationship between asexual cytoadherence and gametocytogenesis suggests that expression of these phenotypes is genetically linked. One explanation for this linkage is that both developmental pathways share a common cytoadherence mechanism. This proposed biological and genetic linkage between a virulence factor (asexual cytoadherence) and transmissibility (gametocytogenesis) would help explain why a high degree of virulence has evolved and been maintained in falciparum malaria.

Maximizing crop productivity requires effective selection and targeting of cultivars for appropriate production areas. Understanding similarities in cultivar response among test sites and underlying production zones within a crop production region is important for breeders to effectively choose test sites and interpret test data. Thirty years of wheat (Triticum aestivum L.) yield data from the Southern and Northern Regional Performance Nurseries (SRPN and NRPN, respectively) were analyzed in order to determine similarities among test sites and production zones in the Great Plains hard red winter wheat growing area. Correlations of cultivar yields among locations each year were averaged and used as a basis for principal factor analysis. Six intraregional production zones were identified in the SRPN, with six factors accounting for 55% of the variability in the location correlation dependence structure. Four of the factors essentially divided the central plains region on north‐south, east‐west axes, representing the south‐central plains, north‐central plains, southern high plains, and central high plains areas. Five production zones were identified in the NRPN, with five factors accounting for 55% of the variation in the location correlation dependence structure. Factor analysis was used to further classify sites within three of the larger production zones in the SRPN and two in the NRPN. Sixteen smaller production areas were identified within these major zones. Elucidation of intraregional cultivar production zones should facilitate more precise targeting of wheat breeding and evaluation efforts.