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<jats:title>SUMMARY</jats:title><jats:p>In the cyanobacterium <jats:italic>Synechocystis</jats:italic> sp. PCC 6803, translation factor EF‐Tu is inactivated by reactive oxygen species (ROS) via oxidation of Cys82 and the oxidation of EF‐Tu enhances the inhibition of the repair of photosystem II (PSII) by suppressing protein synthesis. In our present study, we generated transformants of <jats:italic>Synechocystis</jats:italic> that overexpressed a mutated form of EF‐Tu, designated EF‐Tu (C82S), in which Cys82 had been replaced by a Ser residue, and ROS‐scavenging enzymes individually or together. Expression of EF‐Tu (C82S) alone in <jats:italic>Synechocystis</jats:italic> enhanced the repair of PSII under strong light, with the resultant mitigation of PSII photoinhibition, but it stimulated the production of ROS. However, overexpression of superoxide dismutase and catalase, together with the expression of EF‐Tu (C82S), lowered intracellular levels of ROS and enhanced the repair of PSII more significantly under strong light, via facilitation of the synthesis <jats:italic>de novo</jats:italic> of the D1 protein. By contrast, the activity of photosystem I was hardly affected in wild‐type cells and in all the lines of transformed cells under the same strong‐light conditions. Furthermore, transformed cells that overexpressed EF‐Tu (C82S), superoxide dismutase, and catalase were able to survive longer under stronger light than wild‐type cells. Thus, the reinforced capacity for both protein synthesis and ROS scavenging allowed both photosynthesis and cell proliferation to tolerate strong light.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Xyloglucan, an important hemicellulose, plays a crucial role in maintaining cell wall structure and cell elongation. However, the effects of xyloglucan on cotton fiber development are not well understood. <jats:italic>GhMUR3</jats:italic> encodes a xyloglucan galactosyltransferase that is essential for xyloglucan synthesis and is highly expressed during fiber elongation. In this study, we report that <jats:italic>GhMUR3</jats:italic> participates in cotton fiber development under the regulation of <jats:italic>GhMYB30</jats:italic>. Overexpression <jats:italic>GhMUR3</jats:italic> affects the fiber elongation and cell wall thickening. Transcriptome showed that the expression of genes involved in secondary cell wall synthesis was prematurely activated in OE‐MUR3 lines. In addition, <jats:italic>GhMYB30</jats:italic> was identified as a key regulator of <jats:italic>GhMUR3</jats:italic> by Y1H, Dual‐Luc, and electrophoretic mobility shift assay (EMSA) assays. <jats:italic>GhMYB30</jats:italic> directly bound the <jats:italic>GhMUR3</jats:italic> promoter and activated <jats:italic>GhMUR3</jats:italic> expression. Furthermore, DAP‐seq of <jats:italic>GhMYB30</jats:italic> was performed to identify its target genes in the whole genome. The results showed that many target genes were associated with fiber development, including cell wall synthesis‐related genes, BR‐related genes, reactive oxygen species pathway genes, and VLCFA synthesis genes. It was demonstrated that <jats:italic>GhMYB30</jats:italic> may regulate fiber development through multiple pathways. Additionally, <jats:italic>GhMYB46</jats:italic> was confirmed to be a target gene of <jats:italic>GhMYB30</jats:italic> by EMSA, and <jats:italic>GhMYB46</jats:italic> was significantly increased in <jats:italic>GhMYB30‐</jats:italic>silenced lines, indicating that <jats:italic>GhMYB30</jats:italic> inhibited <jats:italic>GhMYB46</jats:italic> expression. Overall, these results revealed that <jats:italic>GhMUR3</jats:italic> under the regulation of <jats:italic>GhMYB30</jats:italic> and plays an essential role in cotton fiber elongation and secondary wall thickening. Additionally, <jats:italic>GhMYB30</jats:italic> plays an important role in the regulation of fiber development and regulates fiber secondary wall synthesis by inhibiting the expression of <jats:italic>GhMYB46</jats:italic>.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>High‐temperature stress results in protein misfolding/unfolding and subsequently promotes the accumulation of cytotoxic protein aggregates that can compromise cell survival. Heat shock proteins (HSPs) function as molecular chaperones that coordinate the refolding and degradation of aggregated proteins to mitigate the detrimental effects of high temperatures. However, the relationship between HSPs and protein aggregates in apples under high temperatures remains unclear. Here, we show that an apple (<jats:italic>Malus domestica</jats:italic>) chloroplast‐localized, heat‐sensitive elongation factor Tu (MdEF‐Tu), positively regulates apple thermotolerance when it is overexpressed. Transgenic apple plants exhibited higher photosynthetic capacity and better integrity of chloroplasts during heat stress. Under high temperatures, MdEF‐Tu formed insoluble aggregates accompanied by ubiquitination modifications. Furthermore, we identified a chaperone heat shock protein (MdHsp70), as an interacting protein of MdEF‐Tu. Moreover, we observed obviously elevated MdHsp70 levels in <jats:italic>35S: MdEF‐Tu</jats:italic> apple plants that prevented the accumulation of ubiquitinated MdEF‐Tu aggregates, which positively contributes to the thermotolerance of the transgenic plants. Overall, our results provide new insights into the molecular chaperone function of MdHsp70, which mediates the homeostasis of thermosensitive proteins under high temperatures.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Plant species with large genomes tend to be excluded from climatically more extreme environments with a shorter growing season. Species that occupy such environments are assumed to be under natural selection for more rapid growth and smaller genome size (GS). However, evidence for this is available only for temperate organisms. Here, we study the evolution of GS in two subfamilies of the tropical family Zingiberaceae to find out whether species with larger genomes are confined to environments where the vegetative season is longer. We tested our hypothesis on 337 ginger species from regions with contrasting climates by correlating their GS with an array of plant traits and environmental variables. We revealed 16‐fold variation in GS which was tightly related to shoot seasonality. Negative correlations of GS with latitude, temperature and precipitation emerged in the subfamily Zingiberoidae, demonstrating that species with larger GS are excluded from areas with a shorter growing season. In the subfamily Alpinioideae, GS turned out to be correlated with the type of stem and light requirements and its members cope with seasonality mainly by adaptation to shady and moist habitats. The Ornstein–Uhlenbeck models suggested that evolution in regions with humid climates favoured larger GS than in drier regions. Our results indicate that climate seasonality exerts an upper constraint on GS not only in temperate regions but also in the tropics, unless species with large genomes find alternative ways to escape from that constraint.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Plants and bacteria have distinct pathways to synthesize the bioactive vitamin B1 thiamin diphosphate (TDP). In plants, thiamin monophosphate (TMP) synthesized in the TDP biosynthetic pathway is first converted to thiamin by a phosphatase, which is then pyrophosphorylated to TDP. In contrast, bacteria use a TMP kinase encoded by <jats:italic>ThiL</jats:italic> to phosphorylate TMP to TDP directly. The Arabidopsis <jats:italic>THIAMIN REQUIRING2</jats:italic> (<jats:italic>TH2</jats:italic>)‐encoded phosphatase is involved in TDP biosynthesis. The chlorotic <jats:italic>th2</jats:italic> mutants have high TMP and low thiamin and TDP. Ectopic expression of <jats:italic>Escherichia coli ThiL</jats:italic> and <jats:italic>ThiL‐GFP</jats:italic> rescued the <jats:italic>th2‐3</jats:italic> mutant, suggesting that the bacterial TMP kinase could directly convert TMP into TDP in Arabidopsis. These results provide direct evidence that the chlorotic phenotype of <jats:italic>th2‐3</jats:italic> is caused by TDP rather than thiamin deficiency. Transgenic Arabidopsis harboring engineered ThiL‐GFP targeting to the cytosol, chloroplast, mitochondrion, or nucleus accumulated higher TDP than the wild type (WT). Ectopic expression of <jats:italic>E. coli ThiL</jats:italic> driven by the <jats:italic>UBIQUITIN</jats:italic> (<jats:italic>UBI</jats:italic>) promoter or an endosperm‐specific <jats:italic>GLUTELIN1</jats:italic> (<jats:italic>GT1</jats:italic>) promoter also enhanced TDP biosynthesis in rice. The <jats:italic>pUBI:ThiL</jats:italic> transgenic rice accumulated more TDP and total vitamin B1 in the leaves, and the <jats:italic>pGT1:ThiL</jats:italic> transgenic lines had higher TDP and total vitamin B1 in the seeds than the WT. Total vitamin B1 only increased by approximately 25–30% in the polished and unpolished seeds of the <jats:italic>pGT1:ThiL</jats:italic> transgenic rice compared to the WT. Nevertheless, these results suggest that genetic engineering of a bacterial vitamin B1 biosynthetic gene downstream of TMP can enhance vitamin B1 production in rice.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>The complexity of environmental conditions encountered by plants in the field, or in nature, is gradually increasing due to anthropogenic activities that promote global warming, climate change, and increased levels of pollutants. While in the past it seemed sufficient to study how plants acclimate to one or even two different stresses affecting them simultaneously, the complex conditions developing on our planet necessitate a new approach of studying stress in plants: Acclimation to multiple stress conditions occurring concurrently or consecutively (termed, multifactorial stress combination [MFSC]). In an initial study of the plant response to MFSC, conducted with <jats:italic>Arabidopsis thaliana</jats:italic> seedlings subjected to an MFSC of six different abiotic stresses, it was found that with the increase in the number and complexity of different stresses simultaneously impacting a plant, plant growth and survival declined, even if the effects of each stress involved in such MFSC on the plant was minimal or insignificant. In three recent studies, conducted with different crop plants, MFSC was found to have similar effects on a commercial rice cultivar, a maize hybrid, tomato, and soybean, causing significant reductions in growth, biomass, physiological parameters, and/or yield traits. As the environmental conditions on our planet are gradually worsening, as well as becoming more complex, addressing MFSC and its effects on agriculture and ecosystems worldwide becomes a high priority. In this review, we address the effects of MFSC on plants, crops, agriculture, and different ecosystems worldwide, and highlight potential avenues to enhance the resilience of crops to MFSC.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Polyploidy is an important evolutionary process throughout eukaryotes, particularly in flowering plants. Duplicated gene pairs (homoeologs) in allopolyploids provide additional genetic resources for changes in molecular, biochemical, and physiological mechanisms that result in evolutionary novelty. Therefore, understanding how divergent genomes and their regulatory networks reconcile is vital for unraveling the role of polyploidy in plant evolution. Here, we compared the leaf transcriptomes of recently formed natural allotetraploids (<jats:italic>Tragopogon mirus</jats:italic> and <jats:italic>T. miscellus</jats:italic>) and their diploid parents (<jats:italic>T. porrifolius</jats:italic> X <jats:italic>T. dubius</jats:italic> and <jats:italic>T. pratensis</jats:italic> X <jats:italic>T. dubius</jats:italic>, respectively). Analysis of 35 400 expressed loci showed a significantly higher level of transcriptomic additivity compared to old polyploids; only 22% were non‐additively expressed in the polyploids, with 5.9% exhibiting transgressive expression (lower or higher expression in the polyploids than in the diploid parents). Among approximately 7400 common orthologous regions (COREs), most loci in both allopolyploids exhibited expression patterns that were vertically inherited from their diploid parents. However, 18% and 20.3% of the loci showed novel expression bias patterns in <jats:italic>T. mirus</jats:italic> and <jats:italic>T. miscellus</jats:italic>, respectively. The expression changes of 1500 COREs were explained by <jats:italic>cis</jats:italic>‐regulatory divergence (the condition in which the two parental subgenomes do not interact) between the diploid parents, whereas only about 423 and 461 of the gene expression changes represent <jats:italic>trans</jats:italic>‐effects (the two parental subgenomes interact) in <jats:italic>T. mirus</jats:italic> and <jats:italic>T. miscellus</jats:italic>, respectively. The low degree of both non‐additivity and <jats:italic>trans</jats:italic>‐effects on gene expression may present the ongoing evolutionary processes of the newly formed <jats:italic>Tragopogon</jats:italic> polyploids (~80–90 years).</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Air humidity significantly impacts plant physiology. However, the upstream elements that mediate humidity sensing and adaptive responses in plants remain largely unexplored. In this study, we define high humidity‐induced cellular features of Arabidopsis plants and take a quantitative phosphoproteomics approach to obtain a high humidity‐responsive landscape of membrane proteins, which we reason are likely the early checkpoints of humidity signaling. We found that a brief high humidity exposure (i.e., 0.5 h) is sufficient to trigger extensive changes in membrane protein abundance and phosphorylation. Enrichment analysis of differentially regulated proteins reveals high humidity‐sensitive processes such as ‘transmembrane transport’, ‘response to abscisic acid’, and ‘stomatal movement’. We further performed a targeted screen of mutants, in which high humidity‐responsive pathways/proteins are disabled, to uncover genes mediating high humidity sensitivity. Interestingly, ethylene pathway mutants (i.e., <jats:italic>ein2</jats:italic> and <jats:italic>ein3eil1</jats:italic>) display a range of altered responses, including hyponasty, reactive oxygen species level, and responsive gene expression, to high humidity. Furthermore, we observed a rapid induction of ethylene biosynthesis genes and ethylene evolution after high humidity treatment. Our study sheds light on the potential early signaling events in humidity perception, a fundamental but understudied question in plant biology, and reveals ethylene as a key modulator of high humidity responses in plants.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Kinases are major components of cellular signaling pathways, regulating key cellular activities through phosphorylation. Kinase inhibitors are efficient tools for studying kinase targets and functions, however assessing their kinase specificity <jats:italic>in vivo</jats:italic> is essential. The identification of resistant kinase mutants has been proposed to be the most convincing approach to achieve this goal. Here, we address this issue in plants via a pharmacogenetic screen for mutants resistant to the ATP‐competitive TOR inhibitor AZD‐8055. The eukaryotic TOR (Target of Rapamycin) kinase is emerging as a major hub controlling growth responses in plants largely thanks to the use of ATP‐competitive inhibitors. We identified a dominant mutation in the DFG motif of the Arabidopsis TOR kinase domain that leads to very strong resistance to AZD‐8055. This resistance was characterized by measuring root growth, photosystem II (PSII) activity in leaves and phosphorylation of YAK1 (Yet Another Kinase 1) and RPS6 (Ribosomal protein S6), a direct and an indirect target of TOR respectively. Using other ATP‐competitive TOR inhibitors, we also show that the dominant mutation is particularly efficient for resistance to drugs structurally related to AZD‐8055. Altogether, this proof‐of‐concept study demonstrates that a pharmacogenetic screen in Arabidopsis can be used to successfully identify the target of a kinase inhibitor <jats:italic>in vivo</jats:italic> and therefore to demonstrate inhibitor specificity. Thanks to the conservation of kinase families in eukaryotes, and the possibility of creating amino acid substitutions by genome editing, this work has great potential for extending studies on the evolution of signaling pathways in eukaryotes.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Vegetable oils are rich sources of polyunsaturated fatty acids and energy as well as valuable sources of human food, animal feed, and bioenergy. Triacylglycerols, which are comprised of three fatty acids attached to a glycerol backbone, are the main component of vegetable oils. Here, we review the development and application of multiple‐level omics in major oilseeds and emphasize the progress in the analysis of the biological roles of key genes underlying seed oil content and quality in major oilseeds. Finally, we discuss future research directions in functional genomics research based on current omics and oil metabolic engineering strategies that aim to enhance seed oil content and quality, and specific fatty acids components according to either human health needs or industrial requirements.</jats:p>