Transgenic Rice Research Articles

Isolation and Bioinformatics Analysis of SK2-type of Dehydrin1 (DHN1) Gene from Egyptian Sorghum for Enhancing Salinity Stress Tolerance in Transgenic Rice

Isolation and Bioinformatics Analysis of SK2-type of Dehydrin1 (DHN1) Gene from Egyptian Sorghum for Enhancing Salinity Stress Tolerance in Transgenic Rice

OsbHLH5 Synergically Regulates Phenolamide and Diterpenoid Phytoalexins Involved in the Defense of Rice Against Pathogens

Rice (Oryza sativa) produces phenolamides and diterpenoids as major phytoalexins. Although the biosynthetic pathways of phenolamides and diterpenoids in plants have been revealed, knowledge of their accumulation regulatory mechanisms remains limited, and, in particular, no co-regulatory factor has been identified to date. Here, using a combined co-expression and evolutionary analysis, we identified the basic helix–loop–helix (bHLH) transcription factor OsbHLH5 as a positive bifunctional regulator of phenolamide and diterpenoid biosynthesis in rice. Metabolomic analysis revealed that OsbHLH5 significantly increased the content of phenolamides (such as feruloyl tryptamine (Fer-Trm) and p-coumaroyl tyramine (Cou-Tyr)) and diterpenoid phytoalexins (such as momilactones A, momilactones B) in the overexpression lines, while their content was reduced in the OsbHLH5 knockout lines. Gene expression and dual-luciferase assays revealed that OsbHLH5 activates phenolamide biosynthetic genes (including putrescine hydroxycinnamoyltransferase 3 (OsPHT3), tyramine hydroxycinnamoyltransferases 1/2 (OsTHT1/2), and tryptamine benzoyltransferase 2 (OsTBT2)) as well as diterpenoid biosynthetic genes (including copalyl diphosphate synthase 4 (OsCPS4) and kaurene synthase-like 4/7/10/11 (OsKSL4/7/10/11)). Furthermore, we have demonstrated that OsbHLH5 is induced by jasmonic acid (JA), while pathogen inoculation assays indicated that the overexpression of OsbHLH5 in transgenic rice plants leads to enhanced resistance to Xanthomonas oryzae pv. oryzae (Xoo). Overall, we have identified a positive regulator of phenolamide and diterpenoid biosynthesis and have demonstrated that biotic stress induces phytoalexin accumulation partly in an OsbHLH5-dependent manner, providing new insights into the metabolic interactions involved in pathogen response and offering valuable gene resources for the development, through genetic improvement, of new rice varieties that are resistant to diseases.

OsbHLH6, a basic helix-loop-helix transcription factor, confers arsenic tolerance and root-to-shoot translocation in rice.

Arsenic (As) is extremely toxic to plants, posing a serious concern for food safety. Identification of genes responsive to As is significative for figuring out this issue. Here, we identified a bHLH transcription factor OsbHLH6 that was involved in mediating the processes of As tolerance, uptake, and root-to-shoot translocation in rice. The expression of OsbHLH6 gene was strongly induced after 3 and 48 h of arsenite [As(III)] treatment. The OsbHLH6-overexpressed transgenic rice (OE-OsbHLH6) was sensitive to, while the knockout mutant of OsbHLH6 gene (Osbhlh6) was tolerant to As(III) stress by affecting the contents of reactive oxygen species (ROS) and non-protein thiols (NPT), etc. Knockout of OsbHLH6 gene increased significantly the As concentration in roots, but decreased extensively As accumulation in shoots, compared to that in OE-OsbHLH6 and WT plants. The transcripts of phytochelatins (PCs) synthetase encoding genes OsPCS1 and OsPCS2, as well as As(III) transporter encoding genes OsLsi1 and OsABCC1 were greatly abundant in Osbhlh6 mutants than in OE-OsbHLH6 and WT plants under As(III) stress. In contrast, the expression of OsLsi2 gene was extensively suppressed by As(III) in Osbhlh6 mutants. OsbHLH6 acted as a transcriptional activator to bind directly to the promoter and regulate the expression of OsPrx2 gene that encodes a peroxidase precursor. Moreover, overexpression of OsbHLH6 gene resulted in significant change of expression ofamounts of abiotic stress-related genes, which might partially contribute to the As sensitivity of OE-OsbHLH6 plants. These findings may broaden our understanding of the molecular mechanism of OsbHLH6-mediated As response in rice and provide novel useful genes for rice As stress-resistant breeding.

Genome-wide selection of potential target candidates for RNAi against Nilaparvata lugens

BackgroundNilaparvata lugens is one of the most destructive pests of rice. RNAi-based N. lugens control offers one alternative strategy to traditional chemical insecticides. However, selection of potential target for RNAi against N. lugens remains a major challenge. Only two target genes for nuclear transgenic N. lugens-resistant plants have been screened. Importantly, only one or few potential target genes against N. lugens were screened every time by knowledge of essential genes from model organisms in previous study.ResultsHere, in silico genome-wide selection of potential target genes against N. lugens through homology comparison was performed. Through genome synteny comparisons, about 3.5% of Drosophila melanogaster genome was found to have conserved genomic synteny with N. lugens genome. By using N. lugens proteins to search D. melanogaster homologs defining lethal or sterile phenotype, 358 N. lugens genes were first screened as putative target genes. Transgenic rice lines expressing dsRNA of randomly selected gene (NlRan or NlSRP54) from 358 putative target genes enhanced resistance to N. lugens. After expression check and safety check, 115 N. lugens genes were screened as potential target candidates.ConclusionThe combined efforts in this study firstly provide one in silico genome-wide homology-based screening approach for RNAi-based target genes against N. lugens, which not only offer one new opportunity to batch select potential target candidates in pests of interest, but also will facilitate the selection of RNAi target in many pest species by providing more than one hundred potential target candidates.

A Novel Single Base Mutation in OsSPL42 Leads to the Formation of Leaf Lesions in Rice

Rice spotted-leaf mutants serve as valuable resources for studying plant programmed cell death (PCD) and disease resistance mechanisms, making them crucial for research on disease resistance in rice. Map-based cloning was used to identify and clone the spotted-leaf gene OsSPL42. Then, functional complementation and CRISPR/Cas9 techniques were also employed to further validate the function of this gene. By applying leaf clippings for bacterial blight (BB) inoculation, the BB resistance of different rice lines was assessed. The results in this study were as follows: The OsSPL42 behaved as a recessive nuclear gene and was narrowed down to a 111 kb region on chromosome 8. All T0 transgenic rice plants in the complementation experiments exhibited a wild-type phenotype, without any lesion spots on the rice leaves. This suggests that the LOC_Os08g06100 encoding O-methyltransferase is the candidate gene for the mutant spl42. The OsSpl42 is widely expressed and the OsSPL42-GFP protein is mainly localized in the cytoplasm. OsSPL42 overexpression lines are more susceptible to BBs, which indicates that OsSPL42 may act as a negative regulator of rice resistance to BB. In summary, we speculate that OsSPL42 plays an important role in the regulation of pathogen response, providing new insights into plant defense mechanisms.

Transgenic rice with microbial high-temperature-resistant β-glucosidase gene significantly improved 2-acetyl-1-pyrroline content and edible quality.

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.

Transgenic rice (Oryza sativa L.) varieties exhibit superior salt stress resilience: a comparative study of physiological and biochemical responses in transgenic and non-transgenic genotypes

Transgenic rice (Oryza sativa L.) varieties exhibit superior salt stress resilience: a comparative study of physiological and biochemical responses in transgenic and non-transgenic genotypes

The codon optimised gene produces an active human basic fibroblastic growth factor in rice cell suspension culture

The coding sequence of human basic fibroblast growth factor (hbFGF) was optimised for expression in rice. An expression cassette was constructed by fusing the PCR-amplified RAmy3D promoter, along with its 5’UTR, 3’UTR, and terminator sequences, to the codon-optimised hbFGF sequence. This cassette was inserted into the pCAMBIA1304 shuttle vector, which also contained the RAmy3D signal peptide. Agrobacterium tumefaciens strain LBA 4404 was used to transform rice callus. Among the transformed lines, the callus expressing the highest level of bFGF (38.1 mg/kg fresh weight) was identified via ELISA and selected for establishing a cell suspension culture. Expression and secretion of the recombinant bFGF into the culture medium were observed three days after incubating the transgenic rice cells in sucrose-free medium. The presence of recombinant bFGF was confirmed through Western blot and SDS-PAGE analyses. Furthermore, the rice-derived bFGF effectively stimulated the proliferation of NIH/3T3 cells, demonstrating a comparable biological activity to that of commercial bFGF.

Conserved features and diversity attributes of chimeric RNAs across accessions in four plants.

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.

Ecophysiological Trade-Off Strategies of Three Gramineous Crops in Response to Root Extracts of Phytolacca americana.

The invasive Phytolacca americana L. poses a significant threat to local agroforestry ecosystems due to its allelopathic toxicity. However, the ecophysiological response mechanisms of crops to allelochemicals remain unclear. This study investigated the seedling growth, physiological, and biochemical responses of three gramineous crops to the root extracts of P. americana and identified potential allelochemicals of the invader. The germination and seedling growth of three crops were inhibited by extracts differently, with high-concentration extracts causing more severe inhibition on seedling roots in hydroponic (>57%) than soil culture experiments (>18%). This inhibition may be related to representative secondary metabolites such as fatty acyls, alkaloids, and phenols. Despite the significant inhibition of high-concentration extracts on seedling growth, the levels of soluble sugar, soluble protein, and antioxidant enzymes increased synergistically. Under allelopathic stress, three species enhanced antioxidant enzyme activities and metabolite contents at the cost of reducing their shoot, root biomass, and root/shoot ratio. This may be an ecophysiological growth-defense strategy to bolster their resistance to allelopathy. Interestingly, transgenic rice exhibited greater sensitivity to allelochemicals than wild-type rice, resulting in more pronounced growth inhibition and increased levels of most metabolites and antioxidant enzymes. This study highlights the adaptive strategies of three gramineous crops to the allelopathy of invasive P. americana.

PfGSTF2 endows resistance to quizalofop-p-ethyl in Polypogon fugax by GSH conjugation.

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.

Wheat TaTIFY3B and TaTIFY10A play roles in seed germination and abiotic stress responses in transgenic Arabidopsis and rice

BackgroundSeed 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.ResultsWe 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.ConclusionsThis study offers a novel perspective for understanding the molecular basis of pre-harvest sprouting and provides potential candidate genes for controlling wheat seed germination.

Overexpressing Carbonic Anhydrase Transgenic Rice Plants Maintain the Regular Soil Functions and Microbial Activities of Soil

Background: Genetically modified (GM) crops are focused on establishing desirable traits to support the food demand of increasing populations. The effect of transgenic plants on soil diversity has been highlighted by a lot of researchers. Some of them showed the negative effect of transgenic crop on soil microbes and the food chain. So there is an urgent need to develop transgenic plants with no harmful effects on environmental health. Methods: We have examined the effects salt tolerant carbonic anhydrase overexpressing transgenic rice plants on the physiology of rhizospheric microbes and their enzymatic activities. In the present study, we have used pot experiments in the greenhouse of Centurion University of Technology and management, Bhubaneswar, Odisha, India. Result: No significant variation in the soil properties viz., pH, Eh, organic C, P, K, N, Ca, Mg, S, Na and Fe+2 were observed. The population of bacteria, fungi and nematodes were remained same in the soil. The enzymatic activities like soil dehydrogenase, nitrate reductase, urease and alkaline phosphatase were not significantly affected. Further, plant growth promotion (PGP) functions such as HCN, siderophore, salicylic acid, GA, IAA, zeatin, were, not influenced considerably. The present study ecologically pertinent of salt tolerant CA transgenic rice to usual functions of the rhizospheric organisms.

Tetraspanin 5 orchestrates resilience to salt stress through the regulation of ion and reactive oxygen species homeostasis in rice.

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.

Biofortifying multiple micronutrients and decreasing arsenic accumulation in rice grain simultaneously by expressing a mutant allele of OAS-TL gene.

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.

Functional Characterization of the Ciliate Stylonychia lemnae Serotonin N-Acetyltransferase, a Pivotal Enzyme in Melatonin Biosynthesis and Its Overexpression Leads to Peroxidizing Herbicide Tolerance in Rice.

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.

Regulation of photosystems II and I depending on N partitioning to Rubisco in rice leaves: a study using Rubisco-antisense transgenic plants.

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.

Multisite Mutagenesis of 4-Hydroxyphenylpyruvate Dioxygenase (HPPD) Enhances Rice Resistance to HPPD Inhibitors and Its Carotenoid Contents.

While frequently used herbicides display limited efficacy against herbicide-resistant weeds, it becomes imperative to explore novel herbicides that ensure both effective weed management and environmental safety. Though 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitory herbicides like mesotrione are prevalent in maize weed management, their integration into rice production is hindered due to the inherent sensitivity of rice HPPD (OsHPPD). In this study, a mutant allele of OsHPPD featuring six amino acid substitutions, termed OsHPPD-6M, maintains enzymatic activity in 200 μm mesotrione while the wild type can only withstand 1 μm. Enzymatic assays in vitro indicated that the HPPD activity of OsHPPD-6M surpassed that of the WT by 2-fold through enhanced substrate-binding. Its overexpression in transgenic rice conferred greater tolerance to mesotrione, topramezone, and isoxaflutole by 36.7-, 41.6-, and 37.1-fold relative to that in the WT rice. Interestingly, these 6M-OE plants demonstrated substantially elevated contents of carotenoids compared to WT plants without a significant impact on agronomic traits.

Phenotypic characterization and evaluation of transgenic indica rice overexpressing SoSPS1 gene in greenhouse trials

Phenotypic characterization and evaluation of transgenic indica rice overexpressing SoSPS1 gene in greenhouse trials

Small DNA elements that act as both insulators and silencers in plants.

Insulators are cis -regulatory elements that separate transcriptional units, whereas silencers are elements that repress transcription regardless of their position. In plants, these elements remain largely uncharacterized. Here, we use the massively parallel reporter assay Plant STARR-seq with short fragments of eight large insulators to identify more than 100 fragments that block enhancer activity. The short fragments can be combined to generate more powerful insulators that abolish the capacity of the strong viral 35S enhancer to activate the 35S minimal promoter. Unexpectedly, when tested upstream of weak enhancers, these fragments act as silencers and repress transcription. Thus, these elements are capable of both insulating or repressing transcription dependent upon regulatory context. We validate our findings in stable transgenic Arabidopsis , maize, and rice plants. The short elements identified here should be useful building blocks for plant biotechnology efforts.