Confirmation and refutation of very luminous galaxies in the early Universe.

During the first 500 million years of cosmic history, the first stars and galaxies formed, seeding the Universe with heavy elements and eventually reionizing the intergalactic medium1-3. Observations with the James Webb Space Telescope (JWST) have uncovered a surprisingly high abundance of candidates for early star-forming galaxies, with distances (redshifts, z), estimated from multiband photometry, as large as z ≈ 16, far beyond pre-JWST limits4-9. Although such photometric redshifts are generally robust, they can suffer from degeneracies and occasionally catastrophic errors. Spectroscopic measurements are required to validate these sources and to reliably quantify physical properties that can constrain galaxy formation models and cosmology10. Here we present JWST spectroscopy that confirms redshifts for two very luminous galaxies with z > 11, and also demonstrates that another candidate with suggested z ≈ 16 instead has z = 4.9, with an unusual combination of nebular line emission and dust reddening that mimics the colours expected for much more distant objects. These results reinforce evidence for the early, rapid formation of remarkably luminous galaxies while also highlighting the necessity of spectroscopic verification. The large abundance of bright, early galaxies may indicate shortcomings in current galaxy formation models or deviations from physical properties (such as the stellar initial mass function) that are generally believed to hold at later times.

Characterization of protein changes associated with sugar beet (Beta vulgaris) resistance and susceptibility to Fusarium oxysporum.

Fusarium oxysporum (F-19) is a serious threat to sugar beet. Resistance exists, but the basis for resistance and disease is unknown. Protein extracts from sugar beet genotypes C1200.XH024 (resistant, R) and Fus7 (susceptible, S) were analyzed by multidimensional liquid chromatography at 2 and 5 days postinoculation (dpi) and compared to mock-inoculated controls. One hundred twenty-one (R) and 73 (S) protein peaks were induced/repressed by F-19, approximately 12 (R) and 8% (S) of the total proteome detected. Temporal protein regulation occurred within and between each genotype, indicating that the timing of expression may be important for resistance. Thirty-one (R) and 48 (S) of the differentially expressed peaks were identified using matrix-assisted laser desorption-ionization with tandem time-of-flight mass spectrometry; others were below detection level. Comparison between the two genotypes uncovered R- and S-specific proteins with potential roles in resistance and disease development, respectively. Use of these proteins to select for new sources of resistance and to develop novel disease control strategies is discussed.

Characterization of a U.S. Isolate of Beet black scorch virus.

ABSTRACT The first reported U.S. isolate of Beet black scorch necrovirus (BBSV) was obtained and characterized. Host range of the virus for localized and occasionally systemic infection included the Chenopodiaceae and Tetragonia expansa; Nicotiana benthamiana supported symptomless systemic infection by the virus. The complete nucleotide sequence of the genomic RNA of the virus, designated BBSV-Co, exhibits 93% similarity to the genome of the 'Ningxia' isolate of BBSV from China. Amino acid sequence similarity in predicted genes ranged from 95% in the p4 gene to 97% in the p82 and coat protein genes. A potential additional gene exists within the U.S. isolate of BBSV that is absent from Chinese isolates of BBSV due to nucleotide differences between these isolates within the coat protein gene. Coat protein analysis by isoelectric focusing and by mass spectroscopy indicated the presence of phosphorylated residues. Using primer extension analysis of the 5' end of the genome and site-directed mutants of genomic clones of BBSV-Co from which infectious RNA was produced, the native 5' end of the BBSV-Co genome was determined to be 5'-GAAACCTAACC...3', lacking the two terminal adenosine nucleotides in the published sequences of BBSV from China.

Influence of glyphosate on Rhizoctonia and Fusarium root rot in sugar beet.

This study tests the effect of glyphosate application on disease severity in glyphosate-resistant sugar beet, and examines whether the increase in disease is fungal or plant mediated. In greenhouse studies of glyphosate-resistant sugar beet, increased disease severity was observed following glyphosate application and inoculation with certain isolates of Rhizoctonia solani Kuhn and Fusarium oxysporum Schlecht. f. sp. betae Snyd. & Hans. Significant increases in disease severity were noted for R. solani AG-2-2 isolate R-9 and moderately virulent F. oxysporum isolate FOB13 on both cultivars tested, regardless of the duration between glyphosate application and pathogen challenge, but not with highly virulent F. oxysporum isolate F-19 or an isolate of R. solani AG-4. The increase in disease does not appear to be fungal mediated, since in vitro studies showed no positive impact of glyphosate on fungal growth or overwintering structure production or germination for either pathogen. Studies of glyphosate impact on sugar beet physiology showed that shikimic acid accumulation is tissue specific and the rate of accumulation is greatly reduced in resistant cultivars when compared with a susceptible cultivar. The results indicate that precautions need to be taken when certain soil-borne diseases are present if weed management for sugar beet is to include post-emergence glyphosate treatments.