Fusarium head blight (FHB) is a destructive disease of cereal crops such as wheat and barley. Previously, expression in wheat of the Arabidopsis NPR1 gene (AtNPR1), which encodes a key regulator of salicylic acid (SA) signaling, was shown to reduce severity of FHB caused by Fusarium graminearum. It was hypothesized that SA signaling contributes to wheat defense against F. graminearum. Here, we show that increased accumulation of SA in fungusinfected spikes correlated with elevated expression of the SA-inducible pathogenesis-related 1 (PR1) gene and FHB resistance. In addition, FHB severity and mycotoxin accumulation were curtailed in wheat plants treated with SA and in AtNPR1 wheat, which is hyper-responsive to SA. In support of a critical role for SA in basal resistance to FHB, disease severity was higher in wheat expressing the NahGencoded salicylate hydroxylase, which metabolizes SA. The FHB-promoting effect of NahG was overcome by application of benzo (1,2,3), thiadiazole-7 carbothioic acid S-methyl ester, a synthetic functional analog of SA, thus confirming an important role for SA signaling in basal resistance to FHB. We further demonstrate that jasmonate signaling has a dichotomous role in wheat interaction with F. graminearum, constraining activation of SA signaling during early stages of infection and promoting resistance during the later stages of infection.

Normalized difference vegetation index (NDVI, computed as [near infrared (NIR) -Red)]/[NIR +Red]) may provide an objective means to evaluate visual quality of turfgrass. The NDVI is influenced by red (visible) and NIR reflectance (invisible), but each may respond differently to environmental factors; basic information is lacking about the two components in relation to turf quality. In this 3-yr study near Manhattan, KS, we examined relationships of NDVI and its component reflectances along with visual quality ratings in Kentucky bluegrass {Poa pratensis L., 'Apollo'), two Kentucky bluegrass x Texas bluegrass {Poa arachnifera Torr.) hybrids (Thermal Blue' and 'Reveille'), and tall fescue {Festuca arundinacea Schreb., 'Dynasty'). Percentage green cover was measured with digital image analysis and shoot density was estimated visually to evaluate their impacts on turf quality and reflectance. Differences in NDVI and red and NIR reflectances were observed among turfgrasses at each level of quality. Across the range of turf quality, NDVI was influenced more strongly by red than NIR reflectance. Red reflectance was strongly affected by density (r = 0.85) and green cover (r = 0.86); NIR reflectance was affected by density (r = 0.63) but negligibly by green cover. Results suggest other fundamental factors that are poorly understood may be affecting NIR reflectance and, hence, NDVI in turf. These factors may confound relationships between NDVI and turf quality and require further study.

Despite breakthroughs in the activity of electrocatalysts for the oxygen reduction reaction (ORR), the development of nanoscale ORR electrocatalysts is still hindered by their instability. Here, to bridge the functional link between activity and stability, wellcontrolled Au@Pt (core@shell) nanoparticles are investigated. In situ monitoring of atomic dissolution and physicochemical analysis in conjunction with theoretical calculations reveal that the atomic-level stability of Au@Pt nanoparticle is attributed to the low surface coverage of OH and oxide on Pt, balancing between strain and ligand effect of Au at the interface. Considering the relationships in activity− stability−oxophilicity, the functional links between activity and stability in the ORR are discussed, and the regulation of oxophilicity is suggested as a guideline for designing highly active and durable electrocatalysts for fuel cell applications.

Canopy spectral reflectance may provide an objective means to evaluate visual quality of turfgrass, but evaluations of quality may be confounded by cultural practices that affect reflectance, such as mowing height. In this 2‐yr study near Manhattan, KS, we examined effects of mowing height on relationships between normalized difference vegetation index (NDVI) and visual quality ratings in Kentucky bluegrass (KBG; Poa pratensis L., ‘Apollo’) and in a KBG × Texas bluegrass (Poa arachnifera Torr.) hybrid (HBG; ‘Thermal Blue’). Mowing heights were 7.62 cm (high) and 3.81 cm (low). The NDVI averaged 4.5 to 7% greater in high‐ than in low‐mown plots. Distinct regression models of visual quality were found at each mowing height and in each species (r2 from 0.40 to 0.81); separate relationships between NDVI and visual quality were also found between years in the same plots. Correlations between NDVI and visual quality were stronger at high than at low mowing heights, possibly because of greater green biomass at high mowing heights. The 95% confidence intervals surrounding predictions of visual quality from NDVI ranged from ±1.34 to 2.75 (on a 1‐to‐9 scale). Thus, lack of precision is a concern when using these models for detection of differences between treatments. Results indicate that when using NDVI to evaluate turfgrass quality, evaluations should be limited to plots maintained at the same mowing height and with the same species to reduce variability in NDVI.

Fusarium graminearum causes Fusarium head blight, an important disease of wheat. F. graminearum can also cause disease in Arabidopsis thaliana. Here, we show that the Arabidopsis LOX1 and LOX5 genes, which encode 9-lipoxygenases (9-LOXs), are targeted during this interaction to facilitate infection. LOX1 and LOX5 expression were upregulated in F. graminearum-inoculated plants and loss of LOX1 or LOX5 function resulted in enhanced disease resistance in the corresponding mutant plants. The enhanced resistance to F. graminearum infection in the lox1 and lox5 mutants was accompanied by more robust induction of salicylic acid (SA) accumulation and signaling and attenuation of jasmonic acid (JA) signaling in response to infection. The lox1- and lox5-conferred resistance was diminished in plants expressing the SA-degrading salicylate hydroxylase or by the application of methyl-JA. Results presented here suggest that plant 9-LOXs are engaged during infection to control the balance between SA and JA signaling to facilitate infection. Furthermore, since silencing of TaLpx-1 encoding a 9-LOX with homology to LOX1 and LOX5, resulted in enhanced resistance against F. graminearum in wheat, we suggest that 9-LOXs have a conserved role as susceptibility factors in disease caused by this important fungus in Arabidopsis and wheat.

Canopy spectrai reflectance may provide an objective means to evaluate visual quality of turfgrass, but evaluations of visual quality may be confounded by differences in reflectance among species or cultivars. In this 3-yr study near Manhattan, KS, we examined effects of species and cultivars on relationships between normalized difference vegetation index (NDVI) and visual quality ratings in Kentucky bluegrass {Poa pratensis L., 'Apollo'), two Kentucky bluegrass x Texas biuegrass {Poa arachnifera Ton.) hybrids (Thermal Blue' and 'Reveille'), and tall fescue {Festuca arundinacea Schreb., 'Dynasty'). A broad range of visual quality was imposed on all four grasses through deficit irrigation and NDVI was measured using broadband spectral radiometry across this range for each grass. Distinct linear regression models of visual quality were found for each grass, and models were also distinct among years in each grass. Relationships between NDVI and visual quality were stronger in the bluegrasses (r^ = 0.41 to 0.83) because they had a greater range in quality under deficit irrigation than tall fescue. The 95% confidence intervals surrounding predictions of visual quality from NDVI ranged from ± 1.25 to 2.10 (on a 1 to 9 scale). Results indicated that the requirement to develop separate models for each grass and in each year, combined with relatively wide confidence intervals, represents a practical limitation to predicting visual quality with NDVI.

The wheat wild relative Aegilops tauschii was previously used to transfer the Lr42 leaf rust resistance gene into bread wheat. Lr42 confers resistance at both seedling and adult stages, and it is broadly effective against all leaf rust races tested to date. Lr42 has been used extensively in the CIMMYT international wheat breeding program with resulting cultivars deployed in several countries. Here, using a bulked segregant RNA-Seq (BSR-Seq) mapping strategy, we identify three candidate genes for Lr42. Overexpression of a nucleotide-binding site leucine-rich repeat (NLR) gene AET1Gv20040300 induces strong resistance to leaf rust in wheat and a mutation of the gene disrupted the resistance. The Lr42 resistance allele is rare in Ae. tauschii and likely arose from ectopic recombination. Cloning of Lr42 provides diagnostic markers and over 1000 CIMMYT wheat lines carrying Lr42 have been developed documenting its widespread use and impact in crop improvement.

Summary Fusarium head blight (FHB) is a disease of the floral tissues of wheat and barley for which highly resistant varieties are not available. Thus, there is a need to identify genes/mechanisms that can be targeted for the control of this devastating disease. Fusarium graminearum is the primary causal agent of FHB in North America. In addition, it also causes Fusarium seedling blight. Fusarium graminearum can also cause disease in the model plant Arabidopsis thaliana . The Arabidopsis– F. graminearum pathosystem has facilitated the identification of targets for the control of disease caused by this fungus. Here, we show that resistance against F. graminearum can be enhanced by flg22, a bacterial microbe‐associated molecular pattern (MAMP). flg22‐induced resistance in Arabidopsis requires its cognate pattern recognition receptor (PRR) FLS2, and is accompanied by the up‐regulation of WRKY29 . The expression of WRKY29 , which is associated with pattern‐triggered immunity (PTI), is also induced in response to F. graminearum infection. Furthermore, WRKY29 is required for basal resistance as well as flg22‐induced resistance to F. graminearum . Moreover, constitutive expression of WRKY29 in Arabidopsis enhances disease resistance. The PTI pathway is also activated in response to F. graminearum infection of wheat. Furthermore, flg22 application and ectopic expression of WRKY29 enhance FHB resistance in wheat. Thus, we conclude that the PTI pathway provides a target for the control of FHB in wheat. We further show that the ectopic expression of WRKY29 in wheat results in shorter stature and early heading time, traits that are important to wheat breeding.