There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Reactive oxygen species

Universal sample preparation method for proteome analysis

The WRKY gene family is among the largest families of transcription factors (TFs) in higher plants. By regulating the plant hormone signal transduction pathway, these TFs play critical roles in some plant processes in response to biotic and abiotic stress. Various bodies of research have demonstrated the important biological functions of WRKY TFs in plant response to different kinds of biotic and abiotic stresses and working mechanisms. However, very little summarization has been done to review their research progress. Not just important TFs function in plant response to biotic and abiotic stresses, WRKY also participates in carbohydrate synthesis, senescence, development, and secondary metabolites synthesis. WRKY proteins can bind to W-box (TGACC (A/T)) in the promoter of its target genes and activate or repress the expression of downstream genes to regulate their stress response. Moreover, WRKY proteins can interact with other TFs to regulate plant defensive responses. In the present review, we focus on the structural characteristics of WRKY TFs and the research progress on their functions in plant responses to a variety of stresses.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/jipb.12513

WRKY transcription factors in plant responses to stresses

Drought stress is one of the major causes of crop loss. WRKY transcription factors, as one of the largest transcription factor families, play important roles in regulation of many plant processes, including drought stress response. However, far less information is available on drought-responsive WRKY genes in wheat (Triticum aestivum L.), one of the three staple food crops. Forty eight putative drought-induced WRKY genes were identified from a comparison between de novo transcriptome sequencing data of wheat without or with drought treatment. TaWRKY1 and TaWRKY33 from WRKY Groups III and II, respectively, were selected for further investigation. Subcellular localization assays revealed that TaWRKY1 and TaWRKY33 were localized in the nuclei in wheat mesophyll protoplasts. Various abiotic stress-related cis-acting elements were observed in the promoters of TaWRKY1 and TaWRKY33. Quantitative real-time PCR (qRT-PCR) analysis showed that TaWRKY1 was slightly up-regulated by high-temperature and abscisic acid (ABA), and down-regulated by low-temperature. TaWRKY33 was involved in high responses to high-temperature, low-temperature, ABA and jasmonic acid methylester (MeJA). Overexpression of TaWRKY1 and TaWRKY33 activated several stress-related downstream genes, increased germination rates, and promoted root growth in Arabidopsis under various stresses. TaWRKY33 transgenic Arabidopsis lines showed lower rates of water loss than TaWRKY1 transgenic Arabidopsis lines and wild type plants during dehydration. Most importantly, TaWRKY33 transgenic lines exhibited enhanced tolerance to heat stress. The functional roles highlight the importance of WRKYs in stress response.

/pdf/drought-responsive-wrky-transcription-factor-genes-tawrky1-3djw9aqlv9.pdf

Drought-responsive WRKY transcription factor genes TaWRKY1 and TaWRKY33 from wheat confer drought and/or heat resistance in Arabidopsis

Polyamine (PA) catabolic processes are performed by copper-containing amine oxidases (CuAOs) and flavin-containing PA oxidases (PAOs). So far, several CuAOs and PAOs have been identified in many plant species. These enzymes exhibit different subcellular localization, substrate specificity, and functional diversity. Since PAs are involved in numerous physiological processes, considerable efforts have been made to explore the functions of plant CuAOs and PAOs during the recent decades. The stress signal transduction pathways usually lead to increase of the intracellular PA levels, which are apoplastically secreted and oxidized by CuAOs and PAOs, with parallel production of hydrogen peroxide (H2O2). Depending on the levels of the generated H2O2, high or low, respectively, either programmed cell death (PCD) occurs or H2O2 is efficiently scavenged by enzymatic/nonenzymatic antioxidant factors that help plants coping with abiotic stress, recruiting different defense mechanisms, as compared to biotic stress. Amine and PA oxidases act further as PA back-converters in peroxisomes, also generating H2O2, possibly by activating Ca2+ permeable channels. Here, the new research data are discussed on the interconnection of PA catabolism with the derived H2O2, together with their signaling roles in developmental processes, such as fruit ripening, senescence, and biotic/abiotic stress reactions, in an effort to elucidate the mechanisms involved in crop adaptation/survival to adverse environmental conditions and to pathogenic infections.

/pdf/polyamine-catabolism-in-plants-a-universal-process-with-4x4oq81wc6.pdf

Polyamine Catabolism in Plants: A Universal Process With Diverse Functions.

Co-infection of apple trees with several viruses/viroids is common and decreases fruit yield and quality. Accurate and rapid detection of these viral pathogens helps to reduce losses and prevent virus spread. Current molecular detection assays used for apple viruses require specialized and expensive equipment. Here, we optimized a CRISPR/Cas12a-based nucleic acid detection platform for the diagnosis of the most prevalent RNA viruses/viroid in apple, namely Apple necrotic mosaic virus (ApNMV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), Apple chlorotic leaf spot virus (ACLSV) and Apple scar skin viroid (ASSVd). We detected each RNA virus/viroid directly from crude leaf extracts after simultaneous multiplex reverse transcription-recombinase polymerase amplification (RT-RPA) with high specificity. Positive results can be distinguished by the naked eye via oligonucleotide-conjugated gold nanoparticles. The CRISPR/Cas12a-RT-RPA platform exhibited comparable sensitivity to RT-qPCR, with limits of detection reaching 250 viral copies per reaction for ASPV and ASGV and 2500 copies for the others. However, this protocol was faster and simpler, requiring an hour or less from leaf harvest. Field tests showed 100% agreement with RT-PCR detection for 52 samples. This novel Cas12a-based method is ideal for rapid and reliable detection of apple viruses in the orchard without the need to send samples to a specialized laboratory.

Field detection of multiple RNA viruses/viroids in apple using a CRISPR/Cas12a-based visual assay.

Several factors affecting the frequency of leaf regeneration of Ziziphus jujuba ‘Huizao’ were investigated in this study, including basal medium, plant growth regulators, leaf maturity, explant orientation, and additive chemicals. The results showed that the highest shoot regeneration frequency (82.25%) was obtained on woody plant medium supplemented with 2.27 μM thidiazuron, 1.07 μM α-naphthalene-acetic acid (NAA) and 2.94 μM silver nitrate after a 10 days incubation in darkness. This study also suggested an increased regeneration frequency of expanded young leaves which were taken from the mid-stem position, as well as from the explant abaxial surface contacting with the medium. In addition, hyperhydric of adventitious buds could be effectively reduced by adding 40 g l−1 sucrose to the medium. A 95.56% rooting rate could be produced from shoots cultured on half-strength Murashige and Skoog (in Physiol Plant 15:473–497, 1962) medium plus 2.69 μM NAA.

Factors influencing efficiency of shoot regeneration in Ziziphus jujuba Mill. 'Huizao'.

Jujube witches’ broom (JWB) is caused by infection with a phytoplasma. A multi-omics approach was taken during graft infection of jujube by JWB-infected scion through the analysis of the plant transcriptome, proteome and phytohormone levels. A high number of differentially expressed genes (DEGs) were identified 37 weeks after grafting (WAG), followed by observation of typical symptoms of JWB at 48 WAG. At 37 WAG, the majority of the upregulated DEGs and differentially expressed proteins (DEPs) were related to flavonoid biosynthesis, phenylalanine metabolism and phenylpropanoid biosynthesis. Two of the four upregulated proteins were similar to jasmonate-induced protein-like. Among the downregulated genes, the two most populated GO terms were plant–pathogen interaction and plant hormone signal transduction (mainly for tryptophan metabolism). Moreover, phytoplasma infection resulted in reduced auxin content and increased jasmonate content, indicating that auxin and jasmonic acid have important roles in regulating jujube responses during the first and second stages of phytoplasma infection. At 48 WAG, the two largest groups of upregulated genes were involved in phenylpropanoid biosynthesis and flavonoid biosynthesis. Both genes and proteins involved in carbon metabolism and carbon fixation in photosynthetic organisms were downregulated, indicating that photosynthesis was affected by the third stage of phytoplasma infection. A multi-omics approach sheds light on the mechanisms of infection and defense at play between jujube trees and an enigmatic pathogen. Phytoplasmas are unculturable bacterial parasites discovered only a few decades ago, which cause deformed growths known as ‘witch's brooms’ in woody plants. A team at Henan Agricultural University, led by Jiancan Feng, explored the mechanisms of phytoplasma infection in the jujube tree (Ziziphus jujuba), by grafting healthy trees with infected branches. They employed a multi-pronged approach, analyzing the trees' gene activity, protein production, and hormone levels following infection. Their results suggest that the plant hormones auxin and jasmonic acid play important early roles in response to phytoplasma infection and that, as the witch's broom developed, processes such as photosynthesis were negatively impacted. These findings underpin future research towards preventing this devastating disease.

/pdf/combination-of-itraq-proteomics-and-rna-seq-transcriptomics-4zjll9x6lp.pdf

Combination of iTRAQ proteomics and RNA-seq transcriptomics reveals multiple levels of regulation in phytoplasma-infected Ziziphus jujuba Mill

Plant stature is one important factor that affects the productivity of peach orchards. However, little is known about the molecular mechanism(s) underlying the dwarf phenotype of peach tree. Here, we report a dwarfing mechanism in the peach cv. FenHuaShouXingTao (FHSXT). The dwarf phenotype of 'FHSXT' was caused by shorter cell length compared to the standard cv. QiuMiHong (QMH). 'FHSXT' contained higher endogenous GA levels than did 'QMH' and did not response to exogenous GA treatment (internode elongation). These results indicated that 'FHSXT' is a GA-insensitive dwarf mutant. A dwarf phenotype-related single nucleotide mutation in the gibberellic acid receptor GID1 was identified in 'FHSXT' (GID1cS191F ), which was also cosegregated with dwarf phenotype in 30 tested cultivars. GID1cS191F was unable to interact with the growth-repressor DELLA1 even in the presence of GA. 'FHSXT' accumulated a higher level of DELLA1, the degradation of which is normally induced by its interaction with GID1. The DELLA1 protein level was almost undetectable in 'QMH', but not reduced in 'FHSXT' after GA3 treatment. Our results suggested that a nonsynonymous single nucleotide mutation in GID1c disrupts its interaction with DELLA1 resulting in a GA-insensitive dwarf phenotype in peach.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/pbi.13094

Jiancan Feng

Papers

Polyamine Catabolism in Plants: A Universal Process With Diverse Functions.

Field detection of multiple RNA viruses/viroids in apple using a CRISPR/Cas12a-based visual assay.

Factors influencing efficiency of shoot regeneration in Ziziphus jujuba Mill. 'Huizao'.

Combination of iTRAQ proteomics and RNA-seq transcriptomics reveals multiple levels of regulation in phytoplasma-infected Ziziphus jujuba Mill

A single nucleotide mutation in GID1c disrupts its interaction with DELLA1 and causes a GA-insensitive dwarf phenotype in peach.