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Transgene‐free genome editing based on clustered regularly interspaced short palindromic repeats (CRISPR) technology is key to achieving genetic engineering in microalgae for basic research and industrial applications. Euglena gracilis, a unicellular phytoflagellate microalga, is a promising biomaterial for foods, feeds, cosmetics and biofuels. However, methods for the genetic manipulation of E. gracilis are still limited. Here, we developed a high‐efficiency, transgene‐free genome editing method for E. gracilis using Lachnospiraceae bacterium CRISPR‐associated protein 12a (LbCas12a) ribonucleoprotein (RNP) complex, which complements the previously established Cas9 RNP‐based method. Through the direct delivery of LbCas12a‐containing RNPs, our method reached mutagenesis rates of approximately 77.2–94.5% at two different E. gracilis target genes, Glucan synthase‐like 2 (EgGSL2) and a phytoene synthase gene (EgcrtB). Moreover, in addition to targeted mutagenesis, we demonstrated efficient knock‐in and base editing at the target site using LbCas12a‐based RNPs with a single‐stranded DNA donor template in E. gracilis. This study extends the genetic engineering capabilities of Euglena to accelerate its basic use for research and engineering for bioproduction. [ABSTRACT FROM AUTHOR]

The 33rd International Conference on Arabidopsis Research (ICAR2023) was held at Makuhari Messe International Conference Hall in Chiba prefecture from June 5 to 9, 2023. This annual conference, which rotates among hosts in North America, Asia–Oceania, and Europe, covers the full range of plant biology research involving Arabidopsis and other plant species. The conference hosted more than 1200 participants, including approximately 800 international attendees from 42 countries (or regions), and featured about 900 oral and poster presentations. Reflecting the conference theme, "Arabidopsis for Sustainable Development Goals (SDGs)," there were numerous exemplary presentations regarding basic plant science using Arabidopsis and translational research conducted to achieve SDGs by exploiting the knowledge gained from Arabidopsis to improve crop production. The conference concluded on a high note, with more than 99% of survey respondents expressing their general satisfaction with ICAR2023. This report aims to summarize the organization, objectives, and outcomes of the conference. [ABSTRACT FROM AUTHOR]

Agriculture is particularly vulnerable to climate change. To cope with the risks posed by climate-related stressors to agricultural production, global population growth, and changes in food preferences, it is imperative to develop new climate-smart crop varieties with increased yield and environmental resilience. Molecular genetics and genomic analyses have revealed that allelic variations in genes involved in phytohormone-mediated growth regulation have greatly improved productivity in major crops. Plant science has remarkably advanced our understanding of the molecular basis of various phytohormone-mediated events in plant life. These findings provide essential information for improving the productivity of crops growing in changing climates. In this review, we highlight the recent advances in plant hormonomics (multiple phytohormone profiling) and discuss its application to crop improvement. We present plant hormonomics as a key tool for deep physiological phenotyping, focusing on representative plant growth regulators associated with the improvement of crop productivity. Specifically, we review advanced methodologies in plant hormonomics, highlighting mass spectrometry- and nanosensor-based plant hormone profiling techniques. We also discuss the applications of plant hormonomics in crop improvement through breeding and agricultural management practices. [ABSTRACT FROM AUTHOR]

The endoplasmic reticulum (ER), a eukaryotic organelle, is the major site of protein biosynthesis. The disturbance of ER function by biotic or abiotic stress triggers the accumulation of misfolded or unfolded proteins in the ER. The unfolded protein response (UPR) is the best-studied ER stress response. This transcriptional regulatory system senses ER stress, activates downstream genes that function to mitigate stress, and restores homeostasis. In addition to its conventional role in stress responses, recent reports indicate that the UPR is involved in plant growth and development. In this review, we summarize the current knowledge of ER stress sensing and the activation and downstream regulation of the UPR. We also describe how the UPR modulates both plant growth and stress tolerance by maintaining ER homeostasis. Lastly, we propose that the UPR is a major component of the machinery that balances the trade-off between plant growth and survival in a dynamic environment. [ABSTRACT FROM AUTHOR]

[12] review the advancements in plant hormonomics (multiple phytohormone profiling), such as plant hormone profiling techniques based on mass spectrometry and nanosensors, and present hormonomics as a potential tool for physiological phenotyping and improvement of crop productivity. Natural or synthetic compounds that can regulate developmental and metabolic processes in higher plants are designated plant growth regulators (PGRs) ([35]). The term "PGRs" is more commonly used in reference to phytohormones and may also comprise inhibitors of phytohormone synthesis or translocation and blockers of their receptors ([33]). Google Scholar OpenURL Placeholder Text WorldCat 26 Malek M., Ghaderi-Far F., Torabi B. and Sadeghipour H.R. (2022) Dynamics of seed dormancy and germination at high temperature stress is affected by priming and phytohormones in rapeseed (Brassica napus L.). [Extracted from the article]

Plants activate a myriad of signaling cascades to tailor adaptive responses under environmental stresses, such as salinity. While the roles of exogenous karrikins (KARs) in salt stress mitigation are well comprehended, genetic evidence of KAR signaling during salinity responses in plants remains unresolved. Here, we explore the functions of the possible KAR receptor KARRIKIN-INSENSITIVE2 (KAI2) in Arabidopsis thaliana tolerance to salt stress by investigating comparative responses of wild-type (WT) and kai2 -mutant plants under a gradient of NaCl. Defects in KAI2 functions resulted in delayed and inhibited cotyledon opening in kai2 seeds compared with WT seeds, suggesting that KAI2 played an important role in enhancing seed germination under salinity. Salt-stressed kai2 plants displayed more phenotypic aberrations, biomass reduction, water loss and oxidative damage than WT plants. kai2 shoots accumulated significantly more Na+ and thus had a lower K+/Na+ ratio, than WT, indicating severe ion toxicity in salt-stressed kai2 plants. Accordingly, kai2 plants displayed a lower expression of genes associated with Na+ homeostasis, such as SALT OVERLY SENSITIVE (SOS) 1, SOS2, HIGH-AFFINITY POTASSIUM TRANSPORTER 1;1 (HKT1;1) and CATION–HYDROGEN EXCHANGER 1 (NHX1) than WT plants. WT plants maintained a better glutathione level, glutathione-related redox status and antioxidant enzyme activities relative to kai2 plants, implying KAI2's function in oxidative stress mitigation in response to salinity. kai2 shoots had lower expression levels of genes involved in the biosynthesis of strigolactones (SLs), salicylic acid and jasmonic acid and the signaling of abscisic acid and SLs than those of WT plants, indicating interactive functions of KAI2 signaling with other hormone signaling in modulating plant responses to salinity. Collectively, these results underpin the likely roles of KAI2 in the alleviation of salinity effects in plants by regulating several physiological and biochemical mechanisms involved in ionic and osmotic balance, oxidative stress tolerance and hormonal crosstalk. [ABSTRACT FROM AUTHOR]

Recent investigations in Arabidopsis thaliana suggest that SUPPRESSOR of MORE AXILLARY GROWTH 2 1 (SMAX1) and SMAX1-LIKE2 (SMXL2) are negative regulators of karrikin (KAR) and strigolactone (SL) signaling during plant growth and development, but their functions in drought resistance and related mechanisms of action remain unclear. To understand the roles and mechanisms of SMAX1 and SMXL2 in drought resistance, we investigated the drought-resistance phenotypes and transcriptome profiles of smax1 smxl2 (s1,2) double-mutant plants in response to drought stress. The s1,2 mutant plants showed enhanced drought-resistance and lower leaf water loss when compared with wild-type (WT) plants. Transcriptome comparison of rosette leaves from the s1,2 mutant and the WT under normal and dehydration conditions suggested that the mechanism related to cuticle formation was involved in drought resistance. This possibility was supported by enhanced cuticle formation in the rosette leaves of the s1,2 mutant. We also found that the s1,2 mutant plants were more sensitive to abscisic acid in assays of stomatal closure, cotyledon opening, chlorophyll degradation and growth inhibition, and they showed a higher reactive oxygen species detoxification capacity than WT plants. In addition, the s1,2 mutant plants had longer root hairs and a higher root-to-shoot ratio than the WT plants, suggesting that the mutant had a greater capacity for water absorption than the WT. Taken together, our results indicate that SMAX1 and SMXL2 negatively regulate drought resistance, and disruption of these KAR- and SL-signaling-related genes may therefore provide a novel means for improving crop drought resistance. [ABSTRACT FROM AUTHOR]

FE UPTAKE‐INDUCING PEPTIDE1 (FEP1), also named IRON MAN3 (IMA3) is a short peptide involved in the iron deficiency response in Arabidopsis thaliana. Recent studies uncovered its molecular function, but its physiological function in the systemic Fe response is not fully understood. To explore the physiological function of FEP1 in iron homoeostasis, we performed a transcriptome analysis using the FEP1 loss‐of‐function mutant fep1‐1 and a transgenic line with oestrogen‐inducible expression of FEP1. We determined that FEP1 specifically regulates several iron deficiency‐responsive genes, indicating that FEP1 participates in iron translocation rather than iron uptake in roots. The iron concentration in xylem sap under iron‐deficient conditions was lower in the fep1‐1 mutant and higher in FEP1‐induced transgenic plants compared with the wild type (WT). Perls staining revealed a greater accumulation of iron in the cortex of fep1‐1 roots than in the WT root cortex, although total iron levels in roots were comparable in the two genotypes. Moreover, the fep1‐1 mutation partially suppressed the iron overaccumulation phenotype in the leaves of the oligopeptide transporter3‐2 (opt3‐2) mutant. These data suggest that FEP1 plays a pivotal role in iron movement and in maintaining the iron quota in vascular tissues in Arabidopsis. [ABSTRACT FROM AUTHOR]

SUMMARY: Nitrate (NO3−) and phosphate (Pi) deficiencies are the major constraints for chickpea productivity, significantly impacting global food security. However, excessive fertilization is expensive and can also lead to environmental pollution. Therefore, there is an urgent need to develop chickpea cultivars that are able to grow on soils deficient in both NO3− and Pi. This study focused on the identification of key NO3− and/or Pi starvation‐responsive metabolic pathways in the leaves and roots of chickpea grown under single and double nutrient deficiencies of NO3− and Pi, in comparison with nutrient‐sufficient conditions. A global metabolite analysis revealed organ‐specific differences in the metabolic adaptation to nutrient deficiencies. Moreover, we found stronger adaptive responses in the roots and leaves to any single than combined nutrient‐deficient stresses. For example, chickpea enhanced the allocation of carbon among nitrogen‐rich amino acids (AAs) and increased the production of organic acids in roots under NO3− deficiency, whereas this adaptive response was not found under double nutrient deficiency. Nitrogen remobilization through the transport of AAs from leaves to roots was greater under NO3− deficiency than double nutrient deficiency conditions. Glucose‐6‐phosphate and fructose‐6‐phosphate accumulated in the roots under single nutrient deficiencies, but not under double nutrient deficiency, and higher glycolytic pathway activities were observed in both roots and leaves under single nutrient deficiency than double nutrient deficiency. Hence, the simultaneous deficiency generated a unique profile of metabolic changes that could not be simply described as the result of the combined deficiencies of the two nutrients. Significance Statement: There is no available information on the adaptive mechanisms, in terms of metabolic changes, which enable plants to respond to double nutrient nitrate (NO3−) and phosphate (Pi) starvation. The results of this study allow us to understand and discover promising key metabolic pathways responsive to single and/or double NO3− and Pi starvation in chickpea plants, which can be targeted for genetic engineering to develop chickpea cultivars that are more productive in N‐ and/or Pi‐poor soils. [ABSTRACT FROM AUTHOR]

SUMMARY: Cytokinin plays an important role in plant stress responses via a multistep signaling pathway, involving the histidine phosphotransfer proteins (HPs). In Arabidopsis thaliana, the AHP2, AHP3 and AHP5 proteins are known to affect drought responses; however, the role of AHP4 in drought adaptation remains undetermined. In the present study, using a loss‐of‐function approach we showed that AHP4 possesses an important role in the response of Arabidopsis to drought. This is evidenced by the higher survival rates of ahp4 than wild‐type (WT) plants under drought conditions, which is accompanied by the downregulated AHP4 expression in WT during periods of dehydration. Comparative transcriptome analysis of ahp4 and WT plants revealed AHP4‐mediated expression of several dehydration‐ and/or abscisic acid‐responsive genes involved in modulation of various physiological and biochemical processes important for plant drought acclimation. In comparison with WT, ahp4 plants showed increased wax crystal accumulation in stems, thicker cuticles in leaves, greater sensitivity to exogenous abscisic acid at germination, narrow stomatal apertures, heightened leaf temperatures during dehydration, and longer root length under osmotic stress. In addition, ahp4 plants showed greater photosynthetic efficiency, lower levels of reactive oxygen species, reduced electrolyte leakage and lipid peroxidation, and increased anthocyanin contents under drought, when compared with WT. These differences displayed in ahp4 plants are likely due to upregulation of genes that encode enzymes involved in reactive oxygen species scavenging and non‐enzymatic antioxidant metabolism. Overall, our findings suggest that AHP4 plays a crucial role in plant drought adaptation. Significance Statement: Loss‐of‐function analysis of the cytokinin signaling member Arabidopsis histidine phosphotransfer protein 4 revealed its negative role in Arabidopsis adaptation to drought, affecting various physiological and biochemical processes by modulating the expression of a large set of genes, including abscisic acid‐responsive genes. [ABSTRACT FROM AUTHOR]

Anastomosis group AG-1 IA of Rhizoctonia solani Khün has a wide host range and threatens crop production. Various glycosyltransferases secreted by phytopathogenic fungi play an essential role in pathogenicity. Previously, we identified a glycosyltransferase RsIA_GT (AG11A_09161) as a secreted protein-encoding gene of R. solani AG-1 IA, whose expression levels increased during infection in rice. In this study, we further characterized the virulence function of RsIA_GT. It is conserved not only in Basidiomycota, including multiple anastomosis groups of R. solani, but also in other primary fungal taxonomic categories. RsIA_GT possesses a signal peptide (SP) for protein secretion, and its functionality was proven using yeast and Nicotiana benthamiana. The SP-truncated form of RsIA_GT (RsIA_GT(ΔS)) expressed in Escherichia coli-induced lesion-like phenotype in rice leaves when applied to punched leaves. However, Agrobacterium-mediated transient expressions of both the full-length RsIA_GT and RsIA_GT(ΔS) did not induce cell death in N. benthamiana leaves. Instead, only RsIA_GT(ΔS) suppressed the cell death induced by two reference cell death factors BAX and INF1 in N.benthamiana. RsIA_GT(ΔS)R154A D168A D170A, a mutant RsIA_GT(ΔS) for the glycosyltransferase catalytic domain, still suppressed the BAX- or INF1-induced cell death, suggesting that the cell death suppression activity of RsIA_GT(ΔS) would be independent from its enzymatic activity. RsIA_GT(ΔS) also suppressed the H2O2 production and callose deposition and showed an effect on the induction of defense genes associated with the expression of BAX and INF1. The transient expression of RsIA_GT(ΔS) in N. benthamiana enhanced the lesion area caused by R. solani AG-1 IA. The secreted glycosyltransferase, RsIA_GT, of R. solani AG-1 IA is likely to have a dual role in virulence inside and outside of host cells. [ABSTRACT FROM AUTHOR]

Keywords: Euglena gracilis; harvesting efficiency; Cas9 ribonucleoprotein (RNP)-based genome editing; Bardet-Biedl syndrome (BBS) genes EN Euglena gracilis harvesting efficiency Cas9 ribonucleoprotein (RNP)-based genome editing Bardet-Biedl syndrome (BBS) genes 2042 2044 3 11/01/22 20221101 NES 221101 Non-motile photosynthetic flagellates sediment well and thus can be harvested more easily under mass cultivation (Brennan and Owende, 2010). CRISPR/Cas9-mediated generation of non-motile mutants to improve the harvesting efficiency of mass-cultivated Euglena gracilis Here, using our Cas9 ribonucleoprotein (RNP)-based genome-editing technique (Nomura I et al i ., 2019), we targeted the I Bardet-Biedl syndrome (BBS) i genes in I E. gracilis i to generate non-motile strains. [Extracted from the article]

Plants in Mongolian grasslands are exposed to short, dry summers and long, cold winters. These plants should be prepared for fast germination and growth activity in response to the limited summer rainfall. The wild plant species adapted to the Mongolian grassland environment may allow us to explore useful genes, as a source of unique genetic codes for crop improvement. Here, we identified the Chloris virgata Dornogovi accession as the fastest germinating plant in major Mongolian grassland plants. It germinated just 5 h after treatment for germination initiation and showed rapid growth, especially in its early and young development stages. This indicates its high growth potential compared to grass crops such as rice and wheat. By assessing growth recovery after animal bite treatment (mimicked by cutting the leaves with scissors), we found that C. virgata could rapidly regenerate leaves after being damaged, suggesting high regeneration potential against grazing. To analyze the regulatory mechanism involved in the high growth potential of C. virgata , we performed RNA-seq-based transcriptome analysis and illustrated a comprehensive gene expression map of the species. Through de novo transcriptome assembly with the RNA-seq reads from whole organ samples of C. virgata at the germination stage (2 days after germination, DAG), early young development stage (8 DAG), young development stage (17 DAG), and adult development stage (28 DAG), we identified 21,589 unified transcripts (contigs) and found that 19,346 and 18,156 protein-coding transcripts were homologous to those in rice and Arabidopsis , respectively. The best-aligned sequences were annotated with gene ontology groups. When comparing the transcriptomes across developmental stages, we found an over-representation of genes involved in growth regulation in the early development stage in C. virgata. Plant development is tightly regulated by phytohormones such as brassinosteroids, gibberellic acid, abscisic acid, and strigolactones. Moreover, our transcriptome map demonstrated the expression profiles of orthologs involved in the biosynthesis of these phytohormones and their signaling networks. We discuss the possibility that C. virgata phytohormone signaling and biosynthesis genes regulate early germination and growth advantages. Comprehensive transcriptome information will provide a useful resource for gene discovery and facilitate a deeper understanding of the diversity of the regulatory systems that have evolved in C. virgata while adapting to severe environmental conditions. [ABSTRACT FROM AUTHOR]