The N-Terminal Region of Cucumber Mosaic Virus 2a Protein Is Involved in the Systemic Infection in Brassica juncea.

Brassica juncea belongs to the Brassicaceae family and is used as both an oilseed and vegetable crop. As only a few studies have reported on the cucumber mosaic virus (CMV) in B. juncea, we conducted this study to provide a basic understanding of the B. juncea and CMV interactions. B. juncea-infecting CMV (CMV-Co6) and non-infecting CMV (CMV-Rs1) were used. To identify the determinants of systemic infection in B. juncea, we first constructed infectious clones of CMV-Co6 and CMV-Rs1 and used them as pseudo-recombinants. RNA2 of CMV was identified as an important determinant in B. juncea because B. juncea were systemically infected with RNA2-containing pseudo-recombinants; CMV-Co6, R/6/R, and R/6/6 were systemically infected B. juncea. Subsequently, the amino acids of the 2a and 2b proteins were compared, and a chimeric clone was constructed. The chimeric virus R/6Rns/R6cp, containing the C-terminal region of the 2a protein of CMV-Rs1, still infects B. juncea. It is the 2a protein that determines the systemic CMV infection in B. juncea, suggesting that conserved 160G and 214A may play a role in systemic CMV infection in B. juncea.

First report of Tulip Virus X infecting tulip (Tulipa gesneriana) in Korea.

Tulip virus X (tulip virus X, TVX) is a member of the genus Potexvirus (family Alphaflexiviridae) and is a positive single-stranded RNA virus. TVX was described first in Scotland (Mowat 1982), followed by several countries (Yamaji et al. 2001; Tzanetakis et al. 2005; Ward et al. 2008; Dees et al. 2011; Sochacki and Komorowska 2012; Wylie et al. 2019). In April 2021, 86 whole tulip plants showing viral symptoms in leaves (mosaic, yellowing, and malformation) and flowers (color breaking) were collected in Chilgok, Chuncheon, Goseong, Yecheon and Yesan, Korea. Furthermore, high-throughput sequencing was performed to identify viruses that infect tulips in Korea. Total RNA was extracted from pooled the leaves and petals using a Maxwell® 16 LEV Plant RNA Kit (Promega, Madison, USA). We constructed a single library using the TruSeq Stranded Total RNA LT Sample Prep Kit for Plant (Illumina, San Diego, USA). The library was 100 bp paired-end sequenced using Illumina's NovaSeq 6000 (Macrogen, Seoul, Korea) and was assembled de novo using Trinity software version trinityrnaseq_r20140717, with default parameters. The contigs were annotated as in previous study (Lee et al. 2020), revealing a single contig each related to TVX, lily symptomless virus (LSV), and tulip breaking virus (TBV) was generated from 648 million total reads. The TVX-related contig (GenBank ON205948) consisting of 6,076 bp showed 99.52% nucleotide identity (6027/6056 bp) with TVX-J (GenBank AB066288). We conducted an RT-PCR assay to validate the presence of viruses with specific primers as TVX-F5093/R5624 (5'-CTATCCGGACTCATTCTACTTC/GTGCGTTCCAGATAAGCTTG-3'), LSV-F7013/R7338 (5'-CTTGGTCGACAGGGACATAAC/GATTGGAATTGTGCTTTTCAGC-3'), and TBV-F7515/R8116 (5'-GTGTGTCATGGATGATTGTTG/CAACTGATTTGCTACCGCTAG-3'). Consequently, TVX were detected in 13 of 86 samples. Moreover, LSV and TBV were detected in 15 and 26 samples, respectively. However, the yellowing and mosaic observed in the TVX infected samples were not observed in the LSV and TBV infected samples. Subsequently, two TVX amplicons were selected, cloned and sequenced. The obtained sequences were 532 bp and were named YS24 and YS38 (GenBank LC664027 and LC664028), respectively. The Korean isolates showed 98.68% (525/532 bp) and 99.62% (530/532 bp) identity with Australian isolate (GenBank MH886522) in BLASTn analysis. To bioassay for TVX, the infected tulip leaf tissue from which YS24 was obtained was used to sap-inoculate, in triplicates, 15 species of indicator plants (Nicotiana benthamiana, N. clevelandii, N. debneyi, N. glutinosa, N. rustica, N. tabacum, Datura stramonium, Glycine max, Phaseolus vulgaris, Chenopodium amaranticolor, C. quinoa, Cucumis sativus, Cu. melo, Gomphrena globosa, and Tetragonia tetragonioides). After 14 days of inoculation, we observed distinct chlorotic spots on inoculated and upper leaves of C. quinoa, but no symptoms were observed in other indicator plants. In RT-PCR assay using TVX-specific primers, only C. quinoa showed a positive reaction. In previous studies, C. amaranticolor, C. quinoa, G. globosa, and N. benthamiana were known as the experimental host of TVX (Dees et al. 2011; Tzanetakis et al. 2005), but only C. quinoa was confirmed to be susceptible to the Korean isolate. Furthermore, transmission electron microscopy revealed typical flexuous rod-shaped viral particles in the inoculated C. quinoa. To our knowledge, this is the first report of TVX infecting tulips in Korea.

Redox Potential Tuning of s-Tetrazine by Substitution of Electron-Withdrawing/Donating Groups for Organic Electrode Materials.

Herein, we tune the redox potential of 3,6-diphenyl-1,2,4,5-tetrazine (DPT) by introducing various electron-donating/withdrawing groups (methoxy, t-butyl, H, F, and trifluoromethyl) into its two peripheral benzene rings for use as electrode material in a Li-ion cell. By both the theoretical DFT calculations and the practical cyclic voltammetry (CV) measurements, it is shown that the redox potentials (E1/2) of the 1,2,4,5-tetrazines (s-tetrazines) have a strong correlation with the Hammett constant of the substituents. In Li-ion coin cells, the discharge voltages of the s-tetrazine electrodes are successfully tuned depending on the electron-donating/withdrawing capabilities of the substituents. Furthermore, it is found that the heterogeneous electron transfer rate (k0) of the s-tetrazine molecules and Li-ion diffusivity (DLi) in the s-tetrazine electrodes are much faster than conventional electrode active materials.

Mellitic Triimides Showing Three One-Electron Redox Reactions with Increased Redox Potential as New Electrode Materials for Li-Ion Batteries.

The mellitic triimide (MTI) bearing three imide groups on a benzene core with C3 symmetry is proposed as a new building block for organic electrode materials in lithium-ion batteries. MTI was anticipated to deliver a higher theoretical specific capacity of up to 282 mAh g-1 with increased reduction potentials compared with the well-known pyromellitic diimide building block bearing two imide groups because the additional imide group can accept one more electron and provide an electron-withdrawing effect. A model compound, ethyl-substituted mellitic triimide (ETTI), shows three well distinguished and reversible one-electron redox reactions at -0.97, -1.62, and -2.34 V versus Ag/Ag+ in 0.1 m tetrabutylammonium hexafluorophosphate electrolyte, but the redox potentials were increased in 2 m lithium bis(trifluoromethanesulfonyl)imide electrolyte: -0.60 V, -0.86 V, and -1.42 V vs. Ag/Ag+ . The DFT calculations revealed that the unique C3 symmetric structural design leads to the higher reduction potential of MTI in the Li-based electrolyte by formation of a stable 7-membered ring with a Li ion and the two carbonyl oxygen atoms from the adjacent imide groups. In a Li-ion coin cell, the ETTI electrode delivered a specific capacity of 176 mAh g-1 , corresponding to 81 % of capacity utilization, with three clear voltage plateaus. The higher average discharge voltage (2.41 V vs. Li/Li+ ) of ETTI allows it to deliver one of the highest specific energies (421 Wh kg-1 ) among reported diimide-based electrode materials. Finally, its redox mechanism was investigated by ex situ FTIR measurements and DFT calculations.

s-Tetrazines as a New Electrode-Active Material for Secondary Batteries.

Because of the limitations of conventional metal-oxide-based electrodes, studies on organic redox-active materials as alternative electrodes for secondary batteries are emerging. However, reported organic electrode materials are still limited to a few kinds of organic redox groups. Therefore, the development of new redox-active groups for high-performance electrode materials is indispensable. Here, we evaluate s-tetrazine derivatives as a new electrode material in Li-ion batteries and study their charge/discharge mechanisms by ex situ XPS measurements. The porous carbon CMK-3 was introduced to encapsulate the s-tetrazines, which allowed 100 % utilization of the theoretical capacity and stable cycle performance of the s-tetrazines by preventing dissolution of the molecules into the electrolytes. This new class of redox-active group can pave the way for the next-generation of energy storage systems.