Fusarium head blight (FHB) resistance is quantitative and diffi cult to evaluate. Genomic selection (GS) could accelerate FHB resistance breeding. We used U.S. cooperative FHB wheat nursery data to evaluate GS models for several FHB resistance traits including deoxynivalenol (DON) levels. For all traits we compared the models: ridge regression (RR), Bayesian LASSO (BL), reproducing kernel Hilbert spaces (RKHS) regression, random forest (RF) regression, and multiple linear regression (MLR) (fi xed effects). For DON, we evaluated additional prediction methods including bivariate RR models, phenotypes for correlated traits, and RF regression models combining markers and correlated phenotypes as predictors. Additionally, for all traits, we compared different marker sets including genomewide markers, FHB quantitative trait loci (QTL) targeted markers, and both sets combined. Genomic selection accuracies were always higher than MLR accuracies, RF and RKHS regression were often the most accurate methods, and for DON, marker plus trait RF regression was more accurate than all other methods. For all traits except DON, using QTL targeted markers alone led to lower accuracies than using genomewide markers. This study indicates that cooperative FHB nursery data can be useful for GS, and prior information about correlated traits and QTL could be used to improve accuracies in some cases.

The occurrence of epidemics of Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, in U.S. winter wheat (Triticum aestivum L.) during the past two decades led to signifi cant emphasis on development of resistant cultivars. Understanding the genetic diversity, population structure (PS), and linkage disequilibrium (LD) in winter wheat in the eastern United States is important for marker-assisted breeding and association analysis in this germplasm. Lines selected from collaborative FHB screening nurseries were genotyped with simple sequence repeat (SSR), sequence tagged site (STS), and Diversity Array Technology (DArT) markers to assess LD, genetic diversity, and PS. The genomewide average of LD decay to r 2 < 0.2 was 9.9 cM and moderate levels of LD (r 2 > 0.2) were generally constrained to markers less than 5 cM apart. Although the lines evaluated were targeted to distinct production zones of the eastern winter wheat region, cluster and principal component analyses did not detect separation of lines into subpopulations. The short, intense breeding history for scab resistance may have localized effects on LD. Lack of subgroups within our population could be due to intercrossing among common resistant parents and indicate frequent admixture and germplasm exchange among U.S. winter wheat programs focused on development of FHB resistant cultivars.

Phytophthora erythroseptica Pethyb. causes a disease known as pink rot in potatoes, which is responsible for substantial pre and post harvest tuber loss. Disease outbreaks are associated with excessive soil moisture, moderate temperature, late season development, and a lack of potato cultivar resistance. Because disease resistance is becoming less effective, understanding other potential solutions is critical. Mineral nutrition of plants is known to be associated with disease development and severity of many diseases, but is not generally considered in relation to outbreaks of pink rot. Calcium (Ca) is essential and considered one of the most important nutrients associated with plant defense, but it has not been studied or consequently linked to the severity of pink rot in potato. A hydroponic growth system was established to study the effects of calcium on P. erythroseptica infection and colonization in Russet Norkotah potato roots. Russet Norkotah potatoes were grown with 3, 86, 172, and 343 mg L −1 Ca in association with the pathogen. The degree of disease severity was assessed by means of quantitative real time polymerase chain reaction (RT PCR). The suppression of infection and disease severity by increased available Ca was statistically significant, decreasing with each increment of Ca between 3 and 343 mg L −1 . These data provide strong evidence that Ca nutrition is important in disease suppression and that the amount of available soil Ca can affect plant health and the ability of P. erythroseptica to infect the host. Resumen Phytophthora erythroseptica Pethyb causa una enfermedad conocida como pudrición rosa en papa, que es responsable de pérdidas substanciales de tubérculo en pre y post cosecha. Los establecimientos de la enfermedad están asociados con excesiva humedad del suelo, temperatura moderada, desarrollo tardío durante el ciclo y falta de resistencia varietal. Considerando que la resistencia a la enfermedad se ha vuelto menos efectiva, es crítico el entendimiento de otras soluciones potenciales. Se sabe que la nutrición mineral en plantas está asociada con el desarrollo y severidad de muchas enfermedades, pero generalmente no se le considera en relación a los establecimientos de pudrición rosa. El calcio (Ca) es esencial y es considerado como uno de los nutrientes más importantes asociado con la defensa de la planta, pero no ha sido estudiado o ligado consecuentemente a la severidad de la pudrición rosa en papa. Se estableció un sistema de crecimiento hidropónico para estudiar los efectos del calcio en la infección y colonización por P. erythroseptica en raíces de papa Russet Norkotah. Las papas Russet Norkotah se cultivaron con 3, 86, 172, y 343 mg L −1 Ca en asociación con el patógeno. El grado de severidad de la enfermedad se evaluó mediante la reacción en cadena de la polimerasa cuantitativa de tiempo real (RT PCR). La supresión de la infección y de la severidad de la enfermedad mediante el aumento del Ca disponible fue estadísticamente significativa, disminuyendo con cada incremento del Ca ...

Crystallization of organic semiconductor small molecules from solution proceeds in multiple steps. This study describes how asymmetric molecules lead to long-lived transient phases and their impact on carrier mobility for electronic devices.

Pink rot caused by the pathogen Phytophthora erythroseptica Pethyb. causes severe pre-and post-harvest losses in potato. Severe losses of potato from pink rot infection suggest the need for better information on cultural factors associated with disease development. Soil pH has been regarded as a strong influence on disease development as observed by previous studies and by commercial potato growers. A hydroponic growth system was established to study the effects of pH on P. erythroseptica infection and colonization in Russet Norkotah potato roots. Russet Norkotah plantlets were grown in hydroponic nutrient solutions buffered at pH 5, 6, 7, and 8 and evaluated for infection by means of quantitative Real Time PCR. Acidic pH solutions produced a higher proportion of pathogen to host DNA in root tissue, indicating increased infection and colonization at low pH. Thus, pH has a unique and significant influence on the levels of infection from P. erythroseptica and that commercially grown potatoes would likely develop reduced tuber rot if grown in soils with pH at or above 7.Resumen La pudrición rosa, causada, por el patógeno Phytophthora erythroseptica Pethyb, causa severas pérdi-das pre-y post-cosecha en papa. Las grandes pérdidas por la infección de la pudrición rosa sugiere la necesidad de mejor información sobre factores culturales asociados con el desarrollo de la enfermedad. Se ha asociado al pH del suelo como de una fuerte influencia en el desarrollo de la enfermedad, como se ha visto en estudios previos y por los productores comerciales de papa. Se estableció un sistema hidropónico de crecimiento para estudiar los efectos del pH en la infección y colonización por P. erythroseptica en raíces de papa Russet Norkotah. Plántulas de Russet Norkotah se cultivaron en soluciones nutritivas hidropón-icas amortiguadas a pH de 5, 6, 7 y 8 y se evaluaron para infección mediante PCR cuantitativa de tiempo real. Las soluciones de pH ácidos produjeron una proporción mas alta de ADN del patógeno que del hospedante en tejido radical, indicando un aumento en la infección y en la colonización a pH bajo. En consecuencia, el pH tiene una influencia única y significativa en los niveles de infección por P. erythroseptica y es probable que las papas comerciales desarrollen infección reducida de tubérculo si se cultivan en suelos con pH a o arriba de 7.