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BACKGROUND RESULTS CONCLUSION The content of 2‐acetyl‐1‐pyrroline (2‐AP) directly affects the aroma and taste of rice. Δ1‐Pyrroline and methylglyoxal are the precursors of 2‐AP synthesis, and β‐glucosidase plays an important role in the synthesis of methylglyoxal. In this study, β‐glucosidase gene cloned from Pyrococcus furiosus was molecularly modified to obtain the high‐temperature‐resistant β‐glucosidase gene 371‐β‐glucosidase (T371A), which was transformed into kitaake varieties (Oryza sativa L. subsp. japonica) by Agrobacterium‐mediated transformation method, and transgenic rice with heterologous expression of T371A was obtained. Experiments were conducted in transgenic rice to investigate whether this gene had an effect on the synthesis of 2‐AP.Under the optimum reaction temperature of 50°C and cooking temperature of 100°C, the enzyme activity of β‐glucosidase in transgenic rice seeds was prominently increased by 260–280% and 419–426% over that of the control, respectively. The content of 2‐AP in transgenic rice seeds significantly increased by 75–105% under normal temperature and high‐temperature cooking conditions compared with the control. It was also found that transgenic rice increased the content of methylglyoxal and decreased the expression of betaine aldehyde dehydrogenase (BADH2).The high‐temperature‐tolerant β‐glucosidase gene obtained in this study provides an innovative technical strategy for molecular breeding of high‐edible aroma crops and has wide application potential. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

We have previously suggested that in rice (Oryza sativa L.) leaves of different ages and N nutrition statuses, photosystems II and I (PSII and PSI, respectively) are regulated depending on N partitioning to Rubisco, which can determine the magnitude of unutilized light energy. The robustness of this mechanism was tested using Rubisco-antisense transgenic rice plants, in which reduced N partitioning to Rubisco markedly increases unutilized light energy. In wild-type plants, N partitioning to Rubisco tended to be smaller in the leaves at lower positions owing to leaf senescence. In the transgenic plants, N partitioning to Rubisco was generally smaller than in the wild-type plants and was relatively constant among leaf positions. The quantum efficiency of PSII [Y(II)] and quantum yield of non-photochemical quenching [Y(NPQ)] correlated positively and negatively, respectively, with N partitioning to Rubisco irrespective of leaf position or genotype. The oxidation levels of the reaction center chlorophyll of PSI (P700) [Y(ND)] negatively correlated with N partitioning to Rubisco. However, in mature and early senescent leaves of the transgenic plants, Y(ND) was markedly lower than expected from N partitioning to Rubisco. These results suggest that in the transgenic plants, the regulation depending on N partitioning to Rubisco is robust for PSII but fails for PSI in mature and early senescing leaves. In these leaves, the magnitudes of P700 oxidation were found to be less than expected from the Y(II) and Y(NPQ) values. The mechanistic reasons and physiological implications of these phenomena are discussed. [ABSTRACT FROM AUTHOR]

Summary: As a non‐collinear expression form of genetic information, chimeric RNAs increase the complexity of transcriptome in diverse organisms. Although chimeric RNAs have been identified in plants, few common features have been revealed. Here, we systemically explored the landscape of chimeric RNAs across multi‐accession and multi‐tissue using pan‐genome and transcriptome data of four plants: rice, maize, soybean, and Arabidopsis. Among the four species, conserved characteristics of breakpoints and parental genes were discovered. In each species, chimeric RNAs displayed a high level of diversity among accessions, and the clustering of accessions using chimeric events was generally concordant with clustering based on genomic variants, implying a general relationship between genetic variations and chimeric RNAs. Through mass spectrometry, we confirmed a fusion protein OsNDC1‐OsGID1L2 and observed its subcellular localization, which differed from the original proteins. Phenotypic cues in transgenic rice suggest the potential functions of OsNDC1‐OsGID1L2. Moreover, an intriguing chimeric event Os01g0216500–Os01g0216900, generated by a large deletion in basmati rice, also exists in another accession without the deletion, demonstrating its convergence in evolution. Our results illuminate the characteristics and hint at the evolutionary implications of plant chimeric RNAs, which serve as a supplement to genetic variations, thus expanding our understanding of genetic diversity. [ABSTRACT FROM AUTHOR]

Summary Populations of Polypogon fugax have developed resistance to many acetyl‐CoA carboxylase (ACCase)‐inhibiting herbicides. This resistance threats the effectiveness and sustainability of herbicide use. In our previous research, a field P. fugax population exhibited GST‐based metabolic resistance to the widely used ACCase‐inhibiting herbicide quizalofop‐p‐ethyl. Here, in this current study, we identified and characterized two GST genes (named as PfGSTF2 and PfGSTF58) that showed higher expression levels in the resistant than the susceptible population. Transgenic rice calli overexpressing PfGSTF2, but not PfGSTF58, became resistant to quizalofop‐p‐ethyl and haloxyfop‐R‐methyl. This reflects similar cross‐resistance pattern to what was observed in the resistant P. fugax population. Transgenic rice seedlings overexpressing PfGSTF2 also exhibited resistance to quizalofop‐p‐ethyl. In contrast, CRISPR/Cas9 knockout of the orthologue gene in rice seedlings increased their sensitivity to quizalofop‐p‐ethyl. LC–MS analysis of in vitro herbicide metabolism by Escherichia coli‐expressed recombinant PfGSTF2 revealed that quizalofop (but not haloxyfop) was detoxified at the ether bond, generating the GSH‐quizalofop conjugate and a propanoic acid derivative with greatly reduced herbicidal activity. Equally, these two metabolites accumulated at higher levels in the resistant population than the susceptible population. In addition, both recombinant PfGSTF2 and PfGSTF58 can attenuate cytotoxicity by reactive oxygen species (ROS), suggesting a role in plant defence against ROS generated by herbicides. Furthermore, the GST inhibitor (NBD‐Cl) reversed resistance in the resistant population, and PfGSTF2 (but not PfGSTF58) responded to NBD‐Cl inhibition. All these suggest that PfGSTF2 plays a significant role in the evolution of quizalofop resistance through enhanced herbicide metabolism in P. fugax. [ABSTRACT FROM AUTHOR]

SUMMARY: Mature embryos are the main explants of tissue culture used in rice transgenic technology. However, the mechanism of mature embryo callus formation remains unclear. In this study, a microRNA‐mediated gene regulatory network of rice calli was established using degradome sequencing. We identified a microRNA, OsmiR408, that regulates the formation of the callus derived from the mature rice embryo. OsUCLACYANIN 30 (OsUCL 30), a target gene of OsmiR408, was the most abundant cleavage mRNA in rice callus. OsUCL17 was verified as a target gene of OsmiR408 using RNA ligase‐mediated 5′‐RACE. In analysis of the OsmiR408 promoter reporter line and pri‐miR408 transcript level, the promoter activity and transcript level of MIR408 were increased dramatically during callus formation. In phenotypic observations, OsmiR408 knockout caused severe defects in mature embryo callus formation, whereas OsmiR408 overexpression promoted callus formation. Transcriptome analysis demonstrated that OsUCLs and certain genes related to the plant hormone signal transduction and phenylpropanoid‐flavonoid biosynthesis pathway had different differential expression patterns between OsmiR408 knockout and overexpression calli. Thus, OsmiR408 may regulate callus formation mainly by affecting plant hormone signal transduction and phenylpropanoid‐flavonoid biosynthesis pathway. Our findings provide insight into OsmiR408/UCLs module function in callus formation. Significance Statement: A novel function for the miR408 was determined, and its target genes OsUCL8, OsUCL17, and OsUCL30 were verified. miR408 regulates rice callus initiation through affecting plant hormone signal transduction and phenylpropanoid‐flavonoid biosynthesis pathway. This study expands our understanding of the function of OsmiR408 in the process of callus formation and will facilitate genetic manipulation based on callus explants in rice breeding. [ABSTRACT FROM AUTHOR]

Background: Seed germination is a key process in the plant life cycle that affects the vegetative and reproductive stages of plants. Although the JAZ gene family has been characterized in many plants, the relationship between the JAZ gene and seed germination is still unclear. Results: We identified two members of the JAZ family from wheat, TaTIFY3B and TaTIFY10A. TaTIFY3B and TaTIFY10A were localized in both the cell membrane and nucleus. Spatio-temporal expression analysis of TaTIFY3B and TaTIFY10A in wheat revealed that these genes are essential for the preharvest sprouting (PHS) stage of seed development, with expression levels significantly decreasing during the ripening period. Transgenic rice plants overexpressing wheat TaTIFY3B and TaTIFY10A improved seed germination rates. Transgenic Arabidopsis plants overexpressing wheat TaTIFY10A improved seed germination rates and promoted flowering. In addition, abscisic acid (ABA) and jasmonic acid (JA) were found to induce TaTIFY3B and TaTIFY10A expression. Under different ABA concentrations, the seed germination rates of transgenic rice and Arabidopsis overexpressing TaTIFY3B and TaTIFY10A are superior to wild-type (WT) and mutant plants, and the root lengths of Arabidopsis overexpressing TaTIFY3B and TaTIFY10A also change. Under different JA concentrations, there is no difference in the seed germination rate of rice overexpressing TaTIFY3B and TaTIFY10A compared to WT and mutant plants, but there is a significant difference in the seed germination rate and root length of overexpressing Arabidopsis compared to WT and mutant plants. Under different concentrations of salt and drought treatments, the seed germination rate and root length of overexpressing Arabidopsis of TaTIFY3B and TaTIFY10A are affected. Conclusions: This study offers a novel perspective for understanding the molecular basis of pre-harvest sprouting and provides potential candidate genes for controlling wheat seed germination. [ABSTRACT FROM AUTHOR]

Summary Tetraspanins (TETs) are integral membrane proteins, characterized by four transmembrane domains and a unique signature motif in their large extracellular loop. They form dynamic supramolecular complexes called tetraspanin‐enriched microdomains (TEMs), through interactions with partner proteins. In plants, TETs are involved in development, reproduction and immune responses, but their role in defining abiotic stress responses is largely underexplored. We focused on OsTET5, which is differentially expressed under various abiotic stresses and localizes to both plasma membrane and endoplasmic reticulum. Using overexpression and underexpression transgenic lines we demonstrate that OsTET5 contributes to salinity and drought stress tolerance in rice. OsTET5 can interact with itself in yeast, suggesting homomer formation. Immunoblotting of native PAGE of microsomal fraction enriched from OsTET5‐Myc transgenic rice lines revealed multimeric complexes containing OsTET5, suggesting the potential formation of TEM complexes. Transcriptome analysis, coupled with quantitative PCR‐based validation, of OsTET5‐altered transgenic lines unveiled the differential expression patterns of several stress‐responsive genes, as well as those coding for transporters under salt stress. Notably, OsTET5 plays a crucial role in maintaining the ionic equilibrium during salinity stress, particularly by preserving an elevated potassium‐to‐sodium (K+/Na+) ratio. OsTET5 also regulates reactive oxygen species homeostasis, primarily by modulating the gene expression and activities of antioxidant pathway enzymes and proline accumulation. Our comprehensive investigation underscores the multifaceted role of OsTET5 in rice, accentuating its significance in developmental processes and abiotic stress tolerance. These findings open new avenues for potential strategies aimed at enhancing stress resilience and making valuable contributions to global food security. [ABSTRACT FROM AUTHOR]

Summary Rice grains typically contain relatively high levels of toxic arsenic (As) but low levels of essential micronutrients. Biofortification of essential micronutrients while decreasing As accumulation in rice would benefit human nutrition and health. We generated transgenic rice expressing a gain‐of‐function mutant allele astol1 driven by the OsGPX1 promoter. astol1 encodes a plastid‐localized O‐acetylserine (thiol) lyase (OAS‐TL) with Ser189Asn substitution (OsASTOL1S189N), which enhances cysteine biosynthesis by forming an indissociable cysteine synthase complex with its partner serine acetyltransferase (SAT). The effects on growth, As tolerance, and nutrient and As accumulation in rice grain were evaluated in hydroponic, pot and field experiments. The expression of OsASTOL1S189N in pOsGPX1::astol1 transgenic lines enhanced SAT activity, sulphate uptake, biosynthesis of cysteine, glutathione, phytochelatins and nicotianamine, and enhanced tolerance to As. The expression of OsASTOL1S189N decreased As accumulation while increased the accumulation of multiple macronutrients (especially sulphur, nitrogen and potassium) and micronutrients (especially zinc and selenium) in rice grain in a pot experiment and two field experiments, and had little effect on plant growth and grain yield. Our study provides a new strategy to genetically engineer rice to biofortify multiple essential nutrients, reducing As accumulation in rice grain and enhancing As tolerance simultaneously. [ABSTRACT FROM AUTHOR]

Serotonin N-acetyltransferase (SNAT) is a pivotal enzyme for melatonin biosynthesis in all living organisms. It catalyzes the conversion of serotonin to N-acetylserotonin (NAS) or 5-methoxytrypytamine (5-MT) to melatonin. In contrast to animal- and plant-specific SNAT genes, a novel clade of archaeal SNAT genes has recently been reported. In this study, we identified homologues of archaeal SNAT genes in ciliates and dinoflagellates, but no animal- or plant-specific SNAT homologues. Archaeal SNAT homologue from the ciliate Stylonychia lemnae was annotated as a putative N-acetyltransferase. To determine whether the putative S. lemnae SNAT (SlSNAT) exhibits SNAT enzyme activity, we chemically synthesized and expressed the full-length SlSNAT coding sequence (CDS) in Escherichia coli, from which the recombinant SlSNAT protein was purified by Ni2+ affinity column chromatography. The recombinant SlSNAT exhibited SNAT enzyme activity toward serotonin (Km = 776 µM) and 5-MT (Km = 246 µM) as substrates. Furthermore, SlSNAT-overexpressing (SlSNAT-OE) transgenic rice plants showed higher levels of melatonin synthesis than wild-type controls. The SlSNAT-OE rice plants exhibited delayed leaf senescence and tolerance against treatment with the reactive oxygen species (ROS)-inducing herbicide butafenacil by decreasing hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels, suggesting that melatonin alleviates ROS production in vivo. [ABSTRACT FROM AUTHOR]

Genetic transformation is a critical tool for gene manipulation and functional analyses in plants, enabling the exploration of key phenotypes and agronomic traits at the genetic level. While dicotyledonous plants offer various tissues for in vitro culture and transformation, monocotyledonous plants, such as rice, have limited options. This study presents an efficient method for genetically transforming rice (Oryza sativa L.) using seed-derived embryogenic calli as explants. Two target genes were utilized to assess regeneration efficiency: green fluorescent protein (eGFP) and the apple FLOWERING LOCUS T (FT)-like gene (MdFT1). Antisense MdFT1 was cloned into a vector controlled by the rice α-amylase 3D (Ramy3D) promoter, while eGFP was fused to Cas9 under the Ubi promoter. These vectors were introduced separately into rice embryogenic calli from two Korean cultivars using Agrobacterium-mediated transformation. Transgenic seedlings were successfully regenerated via hygromycin selection using an in vitro cultivation system. PCR confirmed stable transgene integration in the transgenic calli and their progeny. Fluorescence microscopy revealed eGFP expression, and antisense MdFT1-expressing lines exhibited notable phenotypic changes, including variations in plant height and grain quality. High transformation efficiency and regeneration frequency were achieved for both tested cultivars. This study demonstrated the effective use of seed-derived embryogenic calli for rice transformation, offering a promising approach for developing transgenic plants in monocot species. [ABSTRACT FROM AUTHOR]

Rice is an important food crop worldwide but is usually susceptible to saline stress. When grown on soil with excessive salt, rice plants experience osmotic, ionic, and oxidative stresses that adversely affect growth performance. γ-Aminobutyric acid (GABA) is a nonproteinogenic amino acid that plays an important role in the metabolic activities of organisms. Glutamate decarboxylase (GAD) is the rate-limiting enzyme in GABA metabolism. Here, we genetically modified rice GAD by overexpression or CRISPR-mediated genome editing. These lines, named gad3-ox1 and gad3-ox2 or gad1/3-ko, were used to explore the effects of endogenous GABA accumulation on salt tolerance in rice. Both the gad3-ox1 and gad3-ox2 lines exhibited significant accumulation of the GABA content, whereas the gad1/3-ko line presented a reduced GABA content in vivo. Notably, the two overexpression lines were markedly resistant to salt stress compared with the wild-type and knockout lines. Furthermore, our results demonstrated that endogenous GABA accumulation in the gad3-ox1 and gad3-ox2 lines increased the contents of antioxidant substances and osmotic regulators, decreased the content of membrane lipid peroxidation products and the Na+ content, and resulted in strong tolerance to salt stress. Together, these data provide a theoretical basis for cultivating rice varieties with strong salt tolerance. [ABSTRACT FROM AUTHOR]

The overproduction of proinflammatory cytokines triggers a variety of diseases. Protopanaxadiol (PPD) and resveratrol are naturally found in plants such as ginseng and have potential anti-inflammatory properties, and resveratrol- and PPD-enriched rice seeds have been previously successfully generated. Herein, the synergistic anti-inflammatory activities of extracts of these enriched seeds were assessed in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. In comparison with treatment using extract prepared from PPD-producing transgenic rice (DJ-PPD) alone, cotreatment with DJ526 and DJ-PPD (TR_3) markedly enhanced the anti-inflammatory activities at a similar (compared to DJ526) or higher (compared to DJ-PPD) level. Cotreatment with DJ526 and DJ-PPD markedly inhibited the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. Thus, DJ526 and DJ-PPD in combination suppressed the expression of phosphorylated (p)-NF-κB p65, p-p38 MAPK, and p-ERK 1/2. Cotreatment with DJ526 and DJ-PPD downregulated the expression of proinflammatory cytokines (IL-1β, IL-6, and TNF-α), LPS receptor (toll-like receptor-4, TLR-4), proinflammatory mediators (nitric oxide and PGE2), and arachidonic acid pathway critical enzyme (COX-2). These findings demonstrate the synergistic potential anti-inflammatory activities of resveratrol- and PPD-enriched rice seed extract. [ABSTRACT FROM AUTHOR]

ABSTRACT Drought drastically affects plant growth, development and productivity. Plants respond to drought stress by enhancing sugar accumulation and water transport. Homeodomain‐leucine zipper (HD‐Zip) transcription factors (TFs) participate in various aspects of plant growth and stress response. However, the internal regulatory mechanism of HD‐Zips in moso bamboo (Phyllostachys edulis) remains largely unknown. In this study, we identified an HD‐Zip member, PeHDZ72, which was highly expressed in bamboo shoots and roots and was induced by drought. Furthermore, PeSTP_46019, PeSWEET_23178 and PeTIP4‐3 were identified as downstream genes of PeHDZ72 in moso bamboo by DAP‐seq. The expressions of these three genes were all induced by drought stress. Y1H, DLR and GUS activity assays demonstrated that PeHDZ72 could bind to three types of HD‐motifs in the promoters of these three genes. Overexpression of PeHDZ72 led to a remarkable enhancement in drought tolerance in transgenic rice, with significantly improved soluble sugar and sucrose contents. Meanwhile, the expressions of OsSTPs, OsSWEETs and OsTIP were all upregulated in transgenic rice under drought stress. Overall, our results indicate that drought stress might induce the expression of PeHDZ72, which in turn activated downstream genes PeSTP_46019, PeSWEET_23178 and PeTIP4‐3, contributing to the improvement of cellular osmotic potential in moso bamboo in response to drought stress. [ABSTRACT FROM AUTHOR]

Ferredoxins (Fds) are crucial in various essential plant metabolic processes, including photosynthesis, fermentation and aerobic nitrogen fixation, due to their role in electron transport rate (ETR). However, the full scope of ferredoxin's function across prokaryotes and eukaryotic plants remains less understood. This study investigated the effect of MtFd from Methanothermobacter thermoautotrophicus on rice photosynthetic efficiency. We found that MtFd was localized in the chloroplasts of rice protoplasts. Transgenic analysis showed that MtFd significantly enhanced the photosynthetic capacity compared to the wild‐type plants. This enhancement was evident through increased ETR, NADPH content and net photosynthetic rates, as well as decreased non‐photochemical quenching (NPQ). Despite similar biomass to wild type plants, MtFd transgenic plants exhibited a marked increase in grain size and the 1000‐grian weight. The elevated ETR and surplus free electrons in transgenic plants result in a considerable rise in cellular ROS content, which in turn enhances the enzymatic activity of the antioxidant system. In summary, our findings suggest that introducing the Fd protein from M. thermoautotrophicus into transgenic rice improves photosynthetic efficiency by accelerating ETR, which triggers the cellular oxidative stress response. [ABSTRACT FROM AUTHOR]

The nuclear factor Y (NF‐Y) has been shown to be involved in plant growth and development in response to various environmental signals. However, the integration of these mechanisms into breeding practices for new cultivars has not been extensively investigated. In this study, the Arabidopsis gene AtNF‐YB1 was introduced into rice, including inbred Kasalath and the hybrids Jinfeng × Chenghui 727 and Jinfeng × Chuanhui 907. The obtained transgenic rice showed early flowering under both natural long day (NLD) and natural short day (NSD) conditions. For the inbred Kasalath, the transgenic lines clearly showed a shorter plant height and lower grain yield, with a decrease in spike length and grain number but more productive panicles. However, the hybrids with AtNF‐YB1 had much smaller or even zero reduction in spike length and grain number and more productive panicles. Thus, maintained or even increased grain yields of the transgenic hybrids were recorded under the NLD conditions. Quantitative PCR analysis indicated that the rice flowering initiation pathways were early activated via the suppression of Ghd7 induction in the transgenic rice. RNA‐Seq further demonstrated that three pathways related to plant photosynthesis were markedly upregulated in both Jinfeng B and the hybrid Jinfeng × Chuanhui 907 with AtNF‐YB1 expression. Moreover, physiological experiments showed an upregulation of photosynthetic rates in the transgenic lines. Taken together, this study suggests that AtNF‐YB1 expression in rice not only induces early flowering but also benefits photosynthesis, which might be used to develop hybrid varieties with early ripening. [ABSTRACT FROM AUTHOR]

Prime editing is a versatile CRISPR/Cas‐based precise genome‐editing technique for crop breeding. Four new types of prime editors (PEs) named PE6a–d were recently generated using evolved and engineered reverse transcriptase (RT) variants from three different sources. In this study, we tested the editing efficiencies of four PE6 variants and two additional PE6 constructs with double‐RT modules in transgenic rice (Oryza sativa) plants. PE6c, with an evolved and engineered RT variant from the yeast Tf1 retrotransposon, yielded the highest prime‐editing efficiency. The average fold change in the editing efficiency of PE6c compared with PEmax exceeded 3.5 across 18 agronomically important target sites from 15 genes. We also demonstrated the feasibility of using two RT modules to improve prime‐editing efficiency. Our results suggest that PE6c or its derivatives would be an excellent choice for prime editing in monocot plants. In addition, our findings have laid a foundation for prime‐editing‐based breeding of rice varieties with enhanced agronomically important traits. [ABSTRACT FROM AUTHOR]

Notwithstanding ongoing efforts through supplementation and fortification programs, the burden of vitamin A deficiency remains high among poor and rural populations. To address this, a pro-vitamin A-enriched genetically modified (GM) rice variety, known as Golden Rice (GR), has been developed as a complementary, cost-effective micronutrient strategy. Despite its potential, the success of its future implementation will heavily rely on the acceptance and purchase intention of target populations. Therefore, this study investigated the determinants of GR purchase intention from a survey of 540 consumers from rural Bangladesh. On average, consumers exhibited a strong intention to purchase GR. Hierarchical regression analysis demonstrated that sociodemographic factors (age), cognitive and behavioral factors (prior knowledge, perceived benefits about GR, attitudes toward GM crops, and dietary choices), and expectations of GR marketing (overall, price, distribution) positively influenced consumers' purchase intention of GR. On the other hand, having more negative risk perceptions and higher income levels reduced consumers' intentions. By using a between-subjects design based on five information treatments, the role of information is examined in two ways, i.e., information length and presentation format. Findings of a series of two-way ANOVAs revealed that exposure to more detailed information about GR significantly influenced consumers' purchase intentions, especially when the level of expectations was low. Additionally, information presented through video or an information wheel proved more effective than text. These findings provide valuable insights for policymakers and health planners in devising communication strategies and decision-making regarding this valuable but controversial micronutrient strategy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phytochrome B variant phyB[G515E] with a slow dark reversion was generated. • phyB[G515E] forms warm temperature-insensitive nuclear photobodies. • PHYB[G515E] expression inhibited the phytochrome interacting factor4-auxin pathway. • PHYB[G515E] transgenic Arabidopsis and rice showed warming-insensitive growth. • phyB[G515E] is a powerful tool for engineering warm temperature-insensitive crops. Ambient temperature-induced hypocotyl elongation in Arabidopsis seedlings is sensed by the epidermis-localized phytochrome B (phyB) and transduced into auxin biosynthesis via a basic helix-loop-helix transcription factor, phytochrome-interacting factor 4 (PIF4). Once synthesized, auxin travels down from the cotyledons to the hypocotyl, triggering hypocotyl cell elongation. Thus, the phyB–PIF4 module involved in thermosensing and signal transduction is a potential genetic target for engineering warm temperature-insensitive plants. This study aims to manipulate warm temperature-induced elongation of plants at the post-translational level using phyB variants with dark reversion, the expression of which is subjected to heat stress. The thermosensitive growth response of Arabidopsis was manipulated by expressing the single amino acid substitution variant of phyB (phyB[G515E]), which exhibited a lower dark reversion rate than wild-type phyB. Other variants with slow (phyB[G564E]) or rapid (phyB[S584F]) dark reversion or light insensitivity (phyB[G767R]) were also included in this study for comparison. Warming-induced transient expression of phyB variants was achieved using heat shock-inducible promoters. Arabidopsis PHYB[G515E] and PHYB[G564E] were also constitutively expressed in rice in an attempt to manipulate the heat sensitivity of a monocotyledonous plant species. At an elevated temperature, Arabidopsis seedlings transiently expressing PHYB[G515E] under the control of a heat shock-inducible promoter exhibited shorter hypocotyls than those expressing PHYB and other PHYB variant genes. This warm temperature-insensitive growth was related to the lowered PIF4 and auxin responses. In addition, transgenic rice seedlings expressing Arabidopsis PHYB[G515E] and PHYB[G564E] showed warm temperature-insensitive shoot growth. Transient expression of phyB variants with altered dark reversion rates could serve as an effective optogenetic technique for manipulating PIF4–auxin-mediated thermomorphogenic responses in plants. [ABSTRACT FROM AUTHOR]

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ROOTHAIRLESS (RHL) is a typical type of basic helix‐loop‐helix (bHLH) transcription factor (TF), which has been reported to participate in various aspects of plant growth and in response to stress. However, the functions of RHL subfamily members in moso bamboo (Phyllostachys edulis) remain unknown. In this study, we identified 14 bHLH genes (PeRHL1–PeRHL14) in moso bamboo. Phylogenetic tree and conserved motif analyses showed that PeRHLs were clustered into three clades. The expression analysis suggested that PeRHL4 was co‐expressed with PeTIP1‐1 and PePHT1‐1 in moso bamboo. Moreover, these three genes were all up‐regulated in moso bamboo under drought stress and phosphate starvation. Y1H, DLR and EMSA assays demonstrated that PeRHL4 could activate the expression of PeTIP1‐1 and PePHT1‐1. Furthermore, overexpression of PeRHL4 could increase both drought and phosphate starvation tolerance in transgenic rice, in which the expression of OsTIPs and OsPHT1s was significantly improved, respectively. Overall, our results indicated that drought stress and phosphate starvation could induce the expression of PeRHL4, which in turn activated downstream genes involved in water and phosphate transport. Collectively, our findings reveal that PeRHL4 acting as a positive regulator contributes to enhancing the tolerance of moso bamboo under drought stress and phosphate starvation. Summary statement: Drought stress and phosphate starvation trigger intricate signalling networks that impact plant growth. This study presents PeRHL4 as a regulatory factor to activate downstream genes for water and phosphate transport, potentially bolstering the tolerance of moso bamboo under stresses. [ABSTRACT FROM AUTHOR]

Plant WRKY transcription factors are responsible for biotic and abiotic stresses and play an important role in enhancing their adaptability. The AtWRKY33 is a gene that functions in response to abiotic stresses such as low temperature, drought, salinity, etc. In this study, a recombinant vector YG8198-ZmWRKY53 carrying the ZmWRKY53, an interspecific homolog of the dicotyledonous AtWRKY33, was transferred to rice plants by Agrobacterium mediated transformation. The ectopic expression of the ZmWRKY53 in transgenic rice plants conferred cold tolerance with a higher accumulation of free proline and water-soluble sugars, an increase in chlorophyll content, a decrease in electrolyte leakage rate and MDA levels compared to control plants. This result suggests that ZmWRKY53 may confer cold tolerance in rice. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) have started to play an important role in pest control, and novel miRNA‐based transgenic insect‐resistant plants are now emerging. However, an environmental risk assessment of these novel transgenic plants expressing insect miRNAs must be undertaken before promoting their application. Here, transgenic miR‐14 rice, which has high resistance to the rice stem borer Chilo suppressalis, was used as an example for evaluation in this study. Taking the tier 1 risk assessment method in Bacillus thuringiensis (Bt) crops as a reference, the effects of the direct exposure of a non‐target parasitoid, Cotesia chilonis, to a high concentration of miRNA were evaluated. The results showed that direct feeding with miR‐14 at high concentration had no significant effects on the biological parameters of Co. chilonis, whereas when miR‐14 was injected into Ch. suppressalis‐parasitized larvae, the development duration of Co. chilonis was significantly affected. In combination with the real conditions of the rice paddy field, it could be inferred that transgenic miR‐14 rice has no significant negative effects on the important non‐target parasitoid, Co. chilonis. These results will provide a foundation for the establishment of a new safety evaluation system for novel RNAi‐based transgenic plants. [ABSTRACT FROM AUTHOR]

[Display omitted] • Steam gasification of a genetically modified (GMO) rice straw is investigated. • GMO rice straw exhibits superior gasification performance compared to regular one. • Co-gasification of GMO rice straw with Giant Miscanthus is investigated. • Seaweed biochar addition can greatly enhance co-gasification with reduced tar. • Promoting synergistic effect by low-cost catalyst for co-gasification is clarified. Future sustainability visions include clean, renewable energy from hydrogen, which can be produced, among other ways, by biomass steam gasification. This study explores strategies addressing the limitations in steam co-gasification of herbaceous biomass, using Monster-TUAT1 rice straw, a genetically modified rice plant with a taller and bigger stalk developed by Tokyo University of Agriculture and Technology (TUAT), and Giant Miscanthus, a promising energy crop, as the feedstock. Firstly, compared with the typical rice straw, the Monster TUAT1 demonstrated superior steam gasification performance with a 1.75 times higher hydrogen gas yield and 27.0 % less tar generation. With a focus on overcoming the challenges posed by high silica content in the Monster TUAT1, co-gasification of it with an energy crop of Giant Miscanthus was performed. However, even under the optimum operation condition (750 °C, steam flowrate: 0.15 g/min), the hydrogen gas yield was only 29.3 mmol/g-C with a tar yield of 27.6 %wt. and a carbon conversion efficiency of 45.9 %, which is deemed unsatisfactory for hydrogen production. Thus, strategies for enhancement were proposed, including the incorporation seaweed biochar with high alkali and alkaline earth species, calcined scallop shell powder, and alkali metal salt into the gasifier. Consequently, the introduction of 10 %wt. of calcined scallop shell resulted in an increase in H 2 yield to 37.0 mmol/g-C and 24.3 % CO 2 reduction. The addition of alkali metal salt led to 43.9 % increase of H 2 product with a 15 %wt. tar yield. The most significant improvement occurred with the introduction of seaweed biochar at 50 %wt., increasing of the hydrogen gas yield to 62.0 mmol/g-C with 86 % of carbon conversion efficiency and tar reduction to 5.5 %. These findings demonstrate the viability of utilizing herbaceous biomass such as rice straw in conjunction with the strategic solutions of co-gasification to overcome constraints in improving hydrogen production. [ABSTRACT FROM AUTHOR]

Cell wall is involved in plant growth and plays pivotal roles in plant adaptation to environmental stresses. Cell wall remodelling may be crucial to salt adaptation in the euhalophyte Salicornia europaea. However, the mechanism underlying this process is still unclear. Here, full‐length transcriptome indicated cell wall‐related genes were comprehensively regulated under salinity. The morphology and cell wall components in S. europaea shoot were largely modified under salinity. Through the weighted gene co‐expression network analysis, SeXTH2 encoding xyloglucan endotransglucosylase/hydrolases, and two SeLACs encoding laccases were focused. Meanwhile, SeEXPB was focused according to expansin activity and the expression profiling. Function analysis in Arabidopsis validated the functions of these genes in enhancing salt tolerance. SeXTH2 and SeEXPB overexpression led to larger cells and leaves with hemicellulose and pectin content alteration. SeLAC1 and SeLAC2 overexpression led to more xylem vessels, increased secondary cell wall thickness and lignin content. Notably, SeXTH2 transgenic rice exhibited enhanced salt tolerance and higher grain yield. Altogether, these genes may function in the succulence and lignification process in S. europaea. This work throws light on the regulatory mechanism of cell wall remodelling in S. europaea under salinity and provides potential strategies for improving crop salt tolerance and yields. Summary Statement: SeXTH2 and SeEXPB enhance cell size, two SeLACs promote xylem differentiation and increase the secondary cell wall thickness, which contribute to plant salt tolerance. [ABSTRACT FROM AUTHOR]

The latest CRISPR-Cas9-mediated genome editing technology is expected to bring about revolution in rice yield and quality improvement, and thus validation of rice transformation protocols using CRISPR-Cas9-gRNA constructs is the need of the hour. Moreover, regeneration of more number of transgenic rice plants is prerequisite for developing genome-edited rice lines, as recalcitrant rice varieties were shown to have lower editing efficiencies which necessities screening of large number of transgenic plants to find the suitable edits. In the present study, we have simplified the Agrobacterium-mediated rice transformation protocol for both Indica and Japonica rice cultivars using CRISPR/Cas9 empty vector construct, and the protocols have been suitably optimized for getting large numbers of the regenerated plantlets within the shortest possible time. The Japonica transgenic lines were obtained within 65 days and for the Indica cultivars, it took about 76–78 days. We also obtained about 90% regeneration efficiency for both Japonica and Indica cultivars. The transformation efficiency was about 97% in the case of Japonica and 69–83% in the case of Indica rice cultivars. Furthermore, we screened the OsWRKY24 gene editing efficiency by transforming rice cultivars with CRISPR/Cas9 construct harbouring sgRNA against OsWRKY24 gene and found about 90% editing efficiency in Japonica rice cultivars, while 30% of the transformed Indica cultivars were found to be edited. This implicated the presence of a robust repair mechanism in the Indica rice cultivars. [ABSTRACT FROM AUTHOR]

Cytosine base editors (CBEs) and adenine base editors (ABEs) enable precise C-to-T and A-to-G edits. Recently, ABE8e, derived from TadA-8e, enhances A-to-G edits in mammalian cells and plants. Interestingly, TadA-8e can also be evolved to confer C-to-T editing. This study compares engineered CBEs derived from TadA-8e in rice and tomato cells, identifying TadCBEa, TadCBEd, and TadCBEd_V106W as efficient CBEs with high purity and a narrow editing window. A dual base editor, TadDE, promotes simultaneous C-to-T and A-to-G editing. Multiplexed base editing with TadCBEa and TadDE is demonstrated in transgenic rice, with no off-target effects detected by whole genome and transcriptome sequencing, indicating high specificity. Finally, two crop engineering applications using TadDE are shown: introducing herbicide resistance alleles in OsALS and creating synonymous mutations in OsSPL14 to resist OsMIR156-mediated degradation. Together, this study presents TadA-8e derived CBEs and a dual base editor as valuable additions to the plant editing toolbox. Base editors are a powerful but underexplored tool for genetic engineering and directed evolution of plants. Here, the authors investigate the editing efficiency and specificity of TadA-8e-derived cytosine base editors and dual base editor TadDE in rice and tomato. [ABSTRACT FROM AUTHOR]

The study of the mechanisms by which melatonin protects against cadmium (Cd) toxicity in plants is still in its infancy, particularly at the molecular level. In this study, the gene encoding a novel serotonin N-acetyltransferase 3 (SNAT3) in rice, a pivotal enzyme in the melatonin biosynthetic pathway, was cloned. Rice (Oryza sativa) OsSNAT3 is the first identified plant ortholog of archaeon Thermoplasma volcanium SNAT. The purified recombinant OsSNAT3 catalyzed the conversion of serotonin and 5-methoxytryptamine to N-acetylserotonin and melatonin, respectively. The suppression of OsSNAT3 by RNAi led to a decline in endogenous melatonin levels followed by a reduction in Cd tolerance in transgenic RNAi rice lines. In addition, the expression levels of genes encoding the endoplasmic reticulum (ER) chaperones BiP3, BiP4, and BiP5 were much lower in RNAi lines than in the wild type. In transgenic rice plants overexpressing OsSNAT3 (SNAT3-OE), however, melatonin levels were higher than in wild-type plants. SNAT3-OE plants also tolerated Cd stress, as indicated by seedling growth, malondialdehyde, and chlorophyll levels. BiP4 expression was much higher in the SNAT3-OE lines than in the wild type. These results indicate that melatonin engineering could help crops withstand Cd stress, resulting in high yields in Cd-contaminated fields. [ABSTRACT FROM AUTHOR]

The main objectives were to evaluate the substantial equivalence of metabolite composition in transgenic rice and its parents, and assess the risk factors in rice from two aspects of metabolomic variation and mycotoxin content. High performance liquid chromatography-mass spectrometry (HPLC-MS) was used to analyze Japonica rice varieties Nip-ponbare (FP1) and PJ574(FP2) and their corresponding transgenic lines (FT16 and FT23). The results were as follows: multivariate statistical methods such as principal component analysis and partial least squares discriminant analysis were used to detect 448 metabolites from rice samples. Different metabolites were screened and it was found that the concentration variations of zearalenone, L-lactate, 10@, 12Z-octadecanodienoic acid and spermine were significantly affected by gene modification or variety differences. There were 9, 23 and 13 unique differential metabolites in group FP1-FP2, FP1-FT16 and FP2-FT23, respectively, with the highest variation in FP1-FT16. The unique differential metabolites of group FP1-FT16 mainly included deoxyguanolate, coffee salt and gluconic acid. The distinct metabolites of FP2-FT23 were mainly prostaglandin B2, L-cystine, 16-hydroxypalmitic acid. The unique differential metabolites of FP1-FP2 consisted of inositol and stearate amides. The effects of transgenic breeding and variety differences were similar, both of which affect arginine biosynthesis and multiple amino acid metabolic pathways to a certain extent, but the variation of metabolic pathways in different varieties of transgenic rice was different. Enzyme-linked immunoassay (ELISA) showed that the zearalenone content in rice samples ranged from 4.2 to 6 !g/kg, with a significant difference between the two parent varieties (A<0.01), but the content of zearalenone in transgenic rices was substantial equivalence to that in the parents. Fusarium was found to be a common endophytic fungus in rice by high-throughput sequencing. Conclusions: Although the variation of metabolic components and metabolic pathways induced by transgenic breeding may affect the nutritional quality of rice, the extent of variation is not greater than that of rice varieties, and it is within the safe range. A low dose (less than 6 g/kg) of Fusarium toxin zearalenone was detected in rice samples from four rice samples by untargeted metabolomic analysis technique. Although lower than the national standard (60 g/kg), Fusarium toxin may be synthesized by endophytic Fusarium fungi in rice, and there is a risk of fungal outbreaks under certain conditions with significant accumulation of toxicity. [ABSTRACT FROM AUTHOR]

Amylose content (AC) stands as a pivotal determinant of rice grain quality, primarily governed by the Waxy gene (Wx). The allelic variation within this gene, particularly the presence of the Wxmp allele derived from the ancestral Wxmq allele, significantly influences AC and is prevalent among soft japonica rice varieties in southern China. Although both alleles are associated with lower AC, there remains a paucity of detailed understanding regarding the interplay between specific functional single nucleotide polymorphisms (SNPs) within these alleles and the overarching rice grain quality. To investigate this, we engineered three distinct transgenic rice lines, each harboring the Wxmp, Wxmq, or Wxb−5c alleles in the background of the glutinous rice cultivar Nip(wx). This suite of transgenic rice lines showcased varying degrees of grain transparency inversely correlated to AC, which in turn influenced other physicochemical properties of the rice grains, such as taste value of cooked rice, gel consistency, and starch pasting properties. Additionally, analyses of gene expression and enzyme activity revealed that the functional SNPs, Ex4-53G to A and Ex5-53T to C, lead to a decline in the activity of granule-bound starch synthase I (GBSSI) without altering expression levels. [ABSTRACT FROM AUTHOR]

The excessive production of melanin can cause skin diseases and hyperpigmentation. In this study, resveratrol contained in Dongjin rice seed (DJ526) was increased through callus induction. The antioxidant capacity of resveratrol-enriched rice callus was evaluated using the ABTS radical scavenging method and was equivalent to that of vitamin C. DJ526 rice callus extract significantly increased antioxidant activities in a concentration-dependent manner. The anti-melanogenesis effects of DJ526 rice callus extract were also evaluated in melan-a cells. Resveratrol-enriched rice callus extract significantly (i) decreased the size and number of melanin-containing cells, (ii) suppressed the activity of cellular tyrosinase and melanin content, (iii) downregulated the expression of microphthalmia-associated transcription factor, tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2, (iv) increased the expression of phosphorylated extracellular signal-regulated kinase 1/2 and protein kinase B, and (v) inhibited the activation of phosphorylated p38 in melan-a cells. From the above observations, DJ526 rice callus extract showed strong antioxidant and anti-melanogenesis activity at the concentration test. These findings indicate the potential of resveratrol-enriched rice callus as a novel agent for controlling hyperpigmentation. [ABSTRACT FROM AUTHOR]

This article discusses the development of new monomeric TALE-linked base editors for editing the plastid genome in rice. The researchers explored different cytidine deaminases to generate these base editors, including a human APOBEC3A variant and an improved cytidine deaminase based on TadA. They evaluated the editing efficiency of these base editors in rice calli and transgenic rice plants, finding that the monomeric TALE-linked base editors induced high-efficiency C-to-T conversions. The researchers also examined the off-target activity of these base editors and discussed the advantages they offer over other base editors. Overall, this study demonstrates the potential of these monomeric TALE-linked base editors for efficient plastid genome editing in rice. [Extracted from the article]

Plants significantly shape root-associated microbiota, making rhizosphere microbes useful environmental indicator organisms for safety assessment. Here, we report the pyrosequencing of the bacterial 16S ribosomal RNA in rhizosphere soil samples collected from transgenic cry1Ab/cry1Ac Bt rice Huahui No. 1 (GM crop) and its parental counterpart, Minghui63. We identified a total of 2579 quantifiable bacterial operational taxonomic units (OTUs). Many treatment-enriched microbial OTUs were identified, including 14 NonGM-enriched OTUs and 10 GM-enriched OTUs. OTUs belonging to the phyla Proteobacteria, Actinobacteria, Acidobacteria, Firmicutes, Nitrospirae, Chlorobi and GN04 were identified as statistically different in abundance between GM and the other two treatments. Compared with the different impacts of different rice varieties on microbiota, the impact of rice planting on microbiota is more obvious. Furthermore, Huahui No. 1 transgenic Bt rice had a greater impact on the rhizosphere bacterial communities than Minghui63. Early developmental stages of the transgenic Bt rice had a significant impact on many Bacillaceae communities. Soil chemical properties were not significantly altered by the presence of transgenic Bt rice. The peak concentration level of Bt protein products was detected during the seedling stage of transgenic Bt rice, which may be an intriguing factor for bacterial diversity variations. Based on these findings, we conclude that transgenic Bt rice has a significant impact on root-associated bacteria. This information may be leveraged in future environmental safety assessments of transgenic Bt rice varieties. [ABSTRACT FROM AUTHOR]

Abiotic stimuli severely restrict the growth and development of plants, resulting in massive losses in the quality and yield of crops. Exploring genes that can improve crop tolerance to abiotic stress is important. In a previous study, we found that overexpression of the Arabidopsis nucleotide-binding domain leucine-rich repeat (NB-LRR) gene AtRPM1(D505V) increased disease resistance in rice. In this research, we found that AtRPM1(D505V) transgenic plants were more sensitive to abscisic acid (ABA) than wild type (WT) plants. Abiotic-stress resistance in AtRPM1(D505V) transgenic plants was investigated. We found that AtRPM1(D505V) transgenic plants exhibited improved resistance to drought and salt stress; the phonotype and survival rates of transgenic rice were better than WT plants. The expression of stress responsive genes including OsDREB2A, OsDREB2B, OsRD22, and OsRD29A were significantly upregulated in AtRPM1(D505V) overexpressed plants than in WT plants. Moreover, the activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) were significantly increased in AtRPM1(D505V) overexpressed plants than in WT plants under drought and salt stress. Under cold stress, the expression of stress responsive genes and the activities of antioxidant enzymes in AtRPM1(D505V) transgenic plants were significantly lower than in WT plants. Our research demonstrated that AtRPM1(D505V) confers drought and salt resistance to transgenic rice. Therefore, AtRPM1(D505V) could act as a potential candidate gene to cultivate drought- and salt-tolerant plants. [ABSTRACT FROM AUTHOR]

The rice receptor kinase XA21 confers broad-spectrum resistance to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of rice bacterial blight disease. To investigate the relationship between the expression level of XA21 and resulting resistance, we generated independent HA-XA21 transgenic rice lines accumulating the XA21 immune receptor fused with an HA epitope tag. Whole-genome sequence analysis identified the T-DNA insertion sites in sixteen independent T0 events. Through quantification of the HA-XA21 protein and assessment of the resistance to Xoo strain PXO99 in six independent transgenic lines, we observed that XA21-mediated resistance is dose dependent. In contrast, based on the four agronomic traits quantified in these experiments, yield is unlikely to be affected by the expression level of HA-XA21. These findings extend our knowledge of XA21-mediated defense and contribute to the growing number of well-defined genomic landing pads in the rice genome that can be targeted for gene insertion without compromising yield. [ABSTRACT FROM AUTHOR]

Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is a widespread and destructive disease in rice production. Previously, we cloned an executor R gene, Xa7, which confers durable and broad-spectrum resistance to BB. Here, we further confirmed that the transcription activator-like effector (TALE) AvrXa7 in Xoo strains could directly bind to the effector-binding element (EBE) in the promoter of the Xa7 gene. Other executor R genes (Xa7, Xa10, Xa23, and Xa27) driven by the promoter of the Xa7 gene could be activated by AvrXa7 and trigger the hypersensitive response (HR) in tobacco leaves. When the expression of the Xa23 gene was driven by the Xa7 promoter, the transgenic rice plants displayed a similar resistance spectrum as the Xa7 gene, demonstrating that the disease resistance characteristics of executor R genes are mainly determined by their induction patterns. Xa7 gene is induced locally by Xoo in the infected leaves, and its induction not only inhibited the growth of incompatible strains but also enhanced the resistance of rice plants to compatible strains, which overcame the shortcomings of its race-specific resistance. Transcriptome analysis of the Xa7 gene constitutive expression in rice plants displayed that Xa7-mediated disease resistance was related to the biosynthesis of lignin and thus enhanced resistance to Xoo. Overall, our results provided novel insights and important resources for further clarifying the molecular mechanisms of the executor R genes. [ABSTRACT FROM AUTHOR]

Background: Development of transgenic rice overexpressing transcription factors involved in drought response has been previously reported to confer drought tolerance and therefore represents a means of crop improvement. We transformed lowland rice IR64 with OsTZF5, encoding a CCCH-tandem zinc finger protein, under the control of the rice LIP9 stress-inducible promoter and compared the drought response of transgenic lines and nulls to IR64 in successive screenhouse paddy and field trials up to the T6 generation. Results: Compared to the well-watered conditions, the level of drought stress across experiments varied from a minimum of − 25 to − 75 kPa at a soil depth of 30 cm which reduced biomass by 30–55% and grain yield by 1–92%, presenting a range of drought severities. OsTZF5 transgenic lines showed high yield advantage under drought over IR64 in early generations, which was related to shorter time to flowering, lower shoot biomass and higher harvest index. However, the increases in values for yield and related traits in the transgenics became smaller over successive generations despite continued detection of drought-induced transgene expression as conferred by the LIP9 promoter. The decreased advantage of the transgenics over generations tended to coincide with increased levels of homozygosity. Background cleaning of the transgenic lines as well as introgression of the transgene into an IR64 line containing major-effect drought yield QTLs, which were evaluated starting at the BC3F1 and BC2F3 generation, respectively, did not result in consistently increased yield under drought as compared to the respective checks. Conclusions: Although we cannot conclusively explain the genetic factors behind the loss of yield advantage of the transgenics under drought across generations, our results help in distinguishing among potential drought tolerance mechanisms related to effectiveness of the transgenics, since early flowering and harvest index most closely reflected the levels of yield advantage in the transgenics across generations while reduced biomass did not. [ABSTRACT FROM AUTHOR]

Sakuranetin plays a key role as a phytoalexin in plant resistance to biotic and abiotic stresses, and possesses diverse health-promoting benefits. However, mature rice seeds do not contain detectable levels of sakuranetin. In the present study, a transgenic rice plant was developed in which the promoter of an endosperm-specific glutelin gene OsGluD-1 drives the expression of a specific enzyme naringenin 7-O-methyltransferase (NOMT) for sakuranetin biosynthesis. The presence of naringenin, which serves as the biosynthetic precursor of sakuranetin made this modification feasible in theory. Liquid chromatography tandem mass spectrometry (LC–MS/MS) validated that the seeds of transgenic rice accumulated remarkable sakuranetin at the mature stage, and higher at the filling stage. In addition, the panicle blast resistance of transgenic rice was significantly higher than that of the wild type. Specially, the matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) imaging was performed to detect the content and spatial distribution of sakuranetin and other nutritional metabolites in transgenic rice seeds. Notably, this genetic modification also did not change the nutritional and quality indicators such as soluble sugars, total amino acids, total flavonoids, amylose, total protein, and free amino acid content in rice. Meanwhile, the phenotypes of the transgenic plant during the whole growth and developmental periods and agricultural traits such as grain width, grain length, and 1000-grain weight exhibited no significant differences from the wild type. Collectively, the study provides a conceptual advance on cultivating sakuranetin-rich biofortified rice by metabolic engineering. This new breeding idea may not only enhance the disease resistance of cereal crop seeds but also improve the nutritional value of grains for human health benefits. [ABSTRACT FROM AUTHOR]

The plant hormone jasmonic acid (JA) is a signalling compound involved in the regulation of cellular defence and development in plants. In this study, we investigated the roles of a JA-responsive MYB transcription factor, JMTF1, in the JA-regulated defence response against rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo). JMTF1 did not interact with any JASMONATE ZIM-domain (JAZ) proteins. Transgenic rice plants overexpressing JMTF1 showed a JA-hypersensitive phenotype and enhanced resistance against Xoo. JMTF1 upregulated the expression of a peroxidase, OsPrx26, and monoterpene synthase, OsTPS24, which are involved in the biosynthesis of lignin and antibacterial monoterpene, γ-terpinene, respectively. OsPrx26 was mainly expressed in the vascular bundle. Transgenic rice plants overexpressing OsPrx26 showed enhanced resistance against Xoo. In addition to the JA-hypersensitive phenotype, the JMTF1-overexpressing rice plants showed a typical auxin-related phenotype. The leaf divergence and shoot gravitropic responses were defective, and the number of lateral roots decreased significantly in the JMTF1-overexpressing rice plants. JMTF1 downregulated the expression of auxinresponsive genes but upregulated the expression of OsIAA13, a suppressor of auxin signalling. The rice gain-of-function mutant Osiaa13 showed high resistance against Xoo. Transgenic rice plants overexpressing OsEXPA4, a JMTF1-downregulated auxinresponsive gene, showed increased susceptibility to Xoo. JMTF1 is selectively bound to the promoter of OsPrx26 in vivo. These results suggest that JMTF1 positively regulates disease resistance against Xoo by coordinating crosstalk between JA- and auxin-signalling in rice. [ABSTRACT FROM AUTHOR]

Mitophagy is a selective autophagy for the degradation of damaged or excessive mitochondria to maintain intracellular homeostasis. In Magnaporthe oryzae, a filamentous ascomycetous fungus that causes rice blast, the most devastating disease of rice, mitophagy occurs in the invasive hyphae to promote infection. To date, only a few proteins are known to participate in mitophagy and the mechanisms of mitophagy are largely unknown in pathogenic fungi. Here, by a yeast two‐hybrid screen with the core autophagy‐related protein MoAtg8 as a bait, we obtained a MoAtg8 interactor MoAti1 (MoAtg8‐interacting protein 1). Fluorescent observations and protease digestion analyses revealed that MoAti1 is primarily localized to the peripheral mitochondrial outer membrane and is responsible for recruiting MoAtg8 to mitochondria under mitophagy induction conditions. MoAti1 is specifically required for mitophagy, but not for macroautophagy and pexophagy. Infection assays suggested that MoAti1 is required for mitophagy in invasive hyphae during pathogenesis. Notably, no homologues of MoAti1 were found in rice and human protein databases, indicating that MoAti1 may be used as a potential target to control rice blast. By the host‐induced gene silencing (HIGS) strategy, transgenic rice plants targeted to silencing MoATI1 showed enhanced resistance against M. oryzae with unchanged agronomic traits. Our results suggest that MoATI1 is required for mitophagy and pathogenicity in M. oryzae and can be used as a target for reducing rice blast. [ABSTRACT FROM AUTHOR]

SUMMARY: 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 ThiL to phosphorylate TMP to TDP directly. The Arabidopsis THIAMIN REQUIRING2 (TH2)‐encoded phosphatase is involved in TDP biosynthesis. The chlorotic th2 mutants have high TMP and low thiamin and TDP. Ectopic expression of Escherichia coli ThiL and ThiL‐GFP rescued the th2‐3 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 th2‐3 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 E. coli ThiL driven by the UBIQUITIN (UBI) promoter or an endosperm‐specific GLUTELIN1 (GT1) promoter also enhanced TDP biosynthesis in rice. The pUBI:ThiL transgenic rice accumulated more TDP and total vitamin B1 in the leaves, and the pGT1:ThiL 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 pGT1:ThiL 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. Significance Statement: Introducing a bacterial gene encoding thiamin monophosphate kinase into Arabidopsis and rice creates an additional route for thiamin diphosphate biosynthesis and increases vitamin B1 contents. [ABSTRACT FROM AUTHOR]

Inorganic phosphate (Pi) homeostasis plays an important role in plant growth and abiotic stress tolerance. Several MYB-CC transcription factors involved in Pi homeostasis have been identified in rice (Oryza sativa). PHOSPHATE STARVATION RESPONSE-LIKE 7 (PHL7) is a class II MYC-CC protein, in which the MYC-CC domain is located at the N terminus. In this study, we established that OsPHL7 is localized to the nucleus and that the encoding gene is induced by Pi deficiency. The Pi-responsive genes and Pi transporter genes are positively regulated by OsPHL7. The overexpression of OsPHL7 enhanced the tolerance of rice plants to Pi starvation, whereas the RNA interference-based knockdown of this gene resulted in increased sensitivity to Pi deficiency. Transgenic rice plants overexpressing OsPHL7 produced more roots than wild-type plants under both Pi-sufficient and Pi-deficient conditions and accumulated more Pi in the shoots and roots. In addition, the overexpression of OsPHL7 enhanced rice tolerance to salt stress. Together, these results demonstrate that OsPHL7 is involved in the maintenance of Pi homeostasis and enhances tolerance to Pi deficiency and salt stress in rice. [ABSTRACT FROM AUTHOR]

This article discusses the development of marker-free transgenic rice that exhibits stable and enhanced resistance to Rice ragged stunt virus (RRSV) and Rice grassy stunt virus (RGSV) through RNA interference (RNAi) technology. Rice virus diseases pose a serious threat to rice production, and the development of resistant varieties is crucial. The researchers used a double T-DNA vector transformation method combined with RNAi technology to construct a dual-action RNAi vector without selectable markers. The marker-free transgenic rice showed strong and stable resistance to the viruses without affecting yield, offering higher biosafety. These findings provide valuable material support for future research on rice virus resistance and germplasm innovation. [Extracted from the article]

This article discusses the development of a transgenic rice line that is resistant to four devastating rice viruses. Traditional breeding for viral resistance in rice is challenging due to the lack of natural resistance sources. The researchers used RNA interference (RNAi) technology to generate transgenic rice plants that express a hairpin RNA construct targeting the viral genomes. The transgenic rice plants showed strong and broad resistance against all four viruses. This study provides a promising approach for engineering viral resistance in rice and potentially other crops. [Extracted from the article]

Genetic transformation is a critical tool for gene manipulation and functional analyses in plants, enabling the exploration of key phenotypes and agronomic traits at the genetic level. While dicotyledonous plants offer various tissues for in vitro culture and transformation, monocotyledonous plants, such as rice, have limited options. This study presents an efficient method for genetically transforming rice (Oryza sativa L.) using seed-derived embryogenic calli as explants. Two target genes were utilized to assess regeneration efficiency: green fluorescent protein (eGFP) and the apple FLOWERING LOCUS T (FT)-like gene (MdFT1). Antisense MdFT1 was cloned into a vector controlled by the rice α-amylase 3D (Ramy3D) promoter, while eGFP was fused to Cas9 under the Ubi promoter. These vectors were introduced separately into rice embryogenic calli from two Korean cultivars using Agrobacterium-mediated transformation. Transgenic seedlings were successfully regenerated via hygromycin selection using an in vitro cultivation system. PCR confirmed stable transgene integration in the transgenic calli and their progeny. Fluorescence microscopy revealed eGFP expression, and antisense MdFT1-expressing lines exhibited notable phenotypic changes, including variations in plant height and grain quality. High transformation efficiency and regeneration frequency were achieved for both tested cultivars. This study demonstrated the effective use of seed-derived embryogenic calli for rice transformation, offering a promising approach for developing transgenic plants in monocot species.

A class I PCF type protein, TCP4, was identified as a transcription factor associated with both grain size and tillering through a DNA pull-down-MS assay combined with a genome-wide association study. This transcription factor was found to have a significant role in the variations among the 533 rice accessions, dividing them into two main subspecies. A Tourist -like miniature inverted-repeat transposable element (MITE) was discovered in the promoter of TCP4 in japonica/geng accessions (TCP4 M+), which was found to suppress the expression of TCP4 at the transcriptional level. The MITE-deleted haplotype (TCP4 M-) was mainly found in indica/xian accessions. ChIP-qPCR and EMSA demonstrated the binding of TCP4 to promoters of grain reservoir genes such as SSIIa and Amy3D in vivo and in vitro , respectively. The introduction of the genomic sequence of TCP4 M+ into different TCP4 M- cultivars was found to affect the expression of TCP4 in the transgenic rice, resulting in decreased expression of its downstream target gene SSIIa , increased tiller number, and decreased seed length. This study revealed that a Tourist -like MITE contributes to subspecies divergence by regulating the expression of TCP4 in response to environmental pressure, thus influencing source-sink balance by regulating starch biosynthesis in rice. [ABSTRACT FROM AUTHOR]