Cloning of the promoter of rice brown planthopper feeding-inducible gene OsTPS31 and identification of related cis-regulatory elements.

BACKGROUND: Brown planthopper (BPH; Nilaparvata lugens) is one of the most serious pests of rice in the world. Insect-resistant genetic engineering is a very effective technology to control BPH. The promoters and cis-regulatory elements inducible by plant-feeding insects are critical for genetic engineering of insect-resistant crops. RESULTS: In this study, we cloned a promoter Ptps31 and a 7 bp cis-regulatory sequence that up-regulated downstream genes induced by BPH feeding. The promoter of OsTPS31 (Ptps31) unresponsive to physical damage but responsive to BPH feeding was cloned and functionally verified. The results showed that expression of the OsBPH14 gene driven by the promoter region from -510 to -246 bp in rice could significantly improve the resistance to BPH. The promoter region from -376 to -370 bp (TAGTGTC) was identified as a cis-regulatory sequence related to BPH feeding induction of downstream gene expression. CONCLUSION: The findings provide a new promoter and a new cis-regulatory sequence tool for the research on and application of rice BPH resistance genes, as well as a new perspective for functional analysis of the OsTPS31 gene. © 2023 Society of Chemical Industry.

QTLs Related to Rice Callus Regeneration Ability: Localization and Effect Verification of qPRR3.

Mature and efficient tissue culture systems are already available for most japonica rice varieties (Oryza sativa ssp. geng). However, it remains challenging to regenerate the majority of indica rice varieties (Oryza sativa ssp. xian). In this study, quantitative trait loci (QTLs) associated with rice callus regeneration ability were identified based on the plant regeneration rate (PRR) and total green plant rate (TGPR) of the 93-11 × Nip recombinant inbred line population. Significant positive correlations were found between PRR and TGPR. A total of three QTLs (one for PRR and two for TGPR) were identified. qPRR3 (located on chromosome 3) was detected for both traits, which could explain 13.40% and 17.07% of the phenotypic variations of PRR and TGPR, respectively. Subsequently, the effect of qPRR3 on callus regeneration ability was validated by cryptographically tagged near-isogenic lines (NILs), and the QTL was narrowed to an interval of approximately 160 kb. The anatomical structure observation of the regenerated callus of the NILs revealed that qPRR3 can improve the callus regeneration ability by promoting the regeneration of shoots.

The Deterioration of Agronomical Traits of the Continuous Cropping of Stevia Is Associated With the Dynamics of Soil Bacterial Community.

Stevia rebaudiana Bertoni is grown worldwide as an important, natural sweetener resource plant. The yield of steviol glycosides (SVglys) is greatly influenced by continuous cropping. In this study, we collected the roots, rhizosphere soils, and bulk soils from 2 years of continuous cropping (Y2) and 8 years of continuous cropping (Y8). A high-throughput sequencing technology based on Illumina Hiseq 2500 platform was used to study the structure and diversity of bacterial communities in the roots and soils of stevia with different years of continuous cropping. The results demonstrated that although the content of a group of SVglys was significantly increased in stevia of long-term continuous cropping, it inhibited the growth of plants and lowered the leaf dry weight; as a result, the total amount of SVglys was significantly decreased. Meanwhile, continuous cropping changed the physicochemical properties and the bacterial composition communities of soil. The different sampling sources of the root, rhizosphere soil, and bulk soil had no impact on the richness of bacterial communities, while it exhibited obvious effects on the diversity of bacterial communities. Continuous cropping had a stronger effect on the bacterial community composition in rhizosphere soil than in root and bulk soil. Based on linear discriminant analysis effect size (LEfSe), in the rhizosphere soil of Y8, the relative abundance of some beneficial bacterial genera of Sphingomonas, Devosia, Streptomyces, and Flavobacterium decreased significantly, while the relative abundance of Polycyclovorans, Haliangium, and Nitrospira greatly increased. Moreover, the soil pH and nutrient content, especially the soil organic matter, were correlated with the relative abundance of predominant bacteria at the genus level. This study provides a theoretical basis for uncovering the mechanism of obstacles in continuous stevia cropping and provides guidance for the sustainable development of stevia.

Regulation of Phytohormones on the Growth and Development of Plant Root Hair.

The tubular-shaped unicellular extensions of plant epidermal cells known as root hairs are important components of plant roots and play crucial roles in absorbing nutrients and water and in responding to stress. The growth and development of root hair include, mainly, fate determination of root hair cells, root hair initiation, and root hair elongation. Phytohormones play important regulatory roles as signal molecules in the growth and development of root hair. In this review, we describe the regulatory roles of auxin, ethylene (ETH), jasmonate (JA), abscisic acid (ABA), gibberellin (GA), strigolactone (SL), cytokinin (CK), and brassinosteroid (BR) in the growth and development of plant root hairs. Auxin, ETH, and CK play positive regulation while BR plays negative regulation in the fate determination of root hair cells; Auxin, ETH, JA, CK, and ABA play positive regulation while BR plays negative regulation in the root hair initiation; Auxin, ETH, CK, and JA play positive regulation while BR, GA, and ABA play negative regulation in the root hair elongation. Phytohormones regulate root hair growth and development mainly by regulating transcription of root hair associated genes, including WEREWOLF (WER), GLABRA2 (GL2), CAPRICE (CPC), and HAIR DEFECTIVE 6 (RHD6). Auxin and ETH play vital roles in this regulation, with JA, ABA, SL, and BR interacting with auxin and ETH to regulate further the growth and development of root hairs.

Research Advances in Cadmium Uptake, Transport and Resistance in Rice (Oryza sativa L.).

Rice (Oryza sativa L.) is one of the most important food crops, feeding half of the world's population. However, rice production is affected by cadmium (Cd) toxicity. Due to an increase in Cd-contaminated soil and rice grains, and the serious harm to human health from Cd, research on Cd uptake, transport and resistance in rice has been widely conducted, and many important advances have been made. Rice plants absorb Cd mainly from soil through roots, which is mediated by Cd absorption-related transporters, including OsNramp5, OsNramp1, OsCd1, OsZIP3, OsHIR1,OsIRT1 and OsIRT2. Cd uptake is affected by soil's environmental factors, such as the concentrations of Cd and some other ions in soil, soil properties, and other factors can affect the bioavailability of Cd in soil. Then, Cd is transported within rice plants mediated by OsZIP6, OsZIP7, OsLCD, OsHMA2, CAL1, OsCCX2, OsLCT1 and OsMTP1, from roots to shoots and from shoots to grains. To resist Cd toxicity, rice has evolved many resistance strategies, including the deposition of Cd in cell walls, vacuolar Cd sequestration, Cd chelation, antioxidation and Cd efflux. In addition, some unresolved scientific questions surrounding Cd uptake, transport and resistance in rice are proposed for further study.

Salt-induced inhibition of rice seminal root growth is mediated by ethylene-jasmonate interaction.

The phytohormones ethylene and jasmonate play important roles in the adaptation of rice plants to salt stress. However, the molecular interactions between ethylene and jasmonate on rice seminal root growth under salt stress are unknown. In this study, the effects of NaCl on the homeostasis of ethylene and jasmonate, and on rice seminal root growth were investigated. Our results indicate that NaCl treatment promotes ethylene biosynthesis by up-regulating the expression of ethylene biosynthesis genes, whereas NaCl-induced ethylene does not inhibit rice seminal root growth directly, but rather indirectly, by promoting jasmonate biosynthesis. NaCl treatment also promotes jasmonate biosynthesis through an ethylene-independent pathway. Moreover, NaCl-induced jasmonate reduces meristem cell number and cell division activity via down-regulated expression of Oryza sativa PLETHORA (OsPLT) and cell division-related genes, respectively. Additionally, NaCl-induced jasmonate inhibits seminal root cell elongation by down-regulating the expression of cell elongation-related genes. Overall, salt stress promotes jasmonate biosynthesis through ethylene-dependent and -independent pathways in rice seminal roots, and jasmonate inhibits rice seminal root growth by inhibiting root meristem cell proliferation and root cell elongation.

Coexpression of I. variabilis-EPSPS* and WBceGO-B3S1 Genes Contributes to High Glyphosate Tolerance and Low Glyphosate Residues in Transgenic Rice.

Weeds are one of the main factors that affect the yield and quality of rice. The combination of glyphosate-resistant transgenic crops and glyphosate is regarded as an important strategy for weed management in modern agriculture. In this study, a codon-optimized glyphosate oxidase gene WBceGO-B3S1 from a variant BceGO-B3S1 and a glyphosate-tolerant gene I. variabilis-EPSPS* from the bacterium Isoptericola variabilis were transformed into an Oryza sativa subsp. geng rice variety Zhonghua11 by Agrobacterium-mediated genetic transformation. Molecular detection and field agronomic trait analysis contributed to the selection of three homozygous lines with stable expression of a single copy of the transferred genes integrated into the intergenic region. Under the treatment of glyphosate at a test amount in the field, transgenic lines exhibited no differences in agronomic traits. Under the treatment by 3600 g ha-1 glyphosate, the glyphosate residues in the aboveground tissues of the three candidate transgenic homozygous lines were significantly lower than those in the transgenic homozygous line with I. variabilis-EPSPS* alone at 1, 5, and 10 days. The transgenic line coexpressing I. variabilis-EPSPS* and WBceGO-B3S1 has great application value in breeding of transgenic rice varieties with high glyphosate resistance and low glyphosate residues. This study is a step forward in solving the problem of herbicide residues in food crops by taking advantage of genes that degrade glyphosate.

Repressed OsMESL expression triggers reactive oxygen species-mediated broad-spectrum disease resistance in rice.

A few reports have indicated that a single gene confers resistance to bacterial blight, sheath blight and rice blast. In this study, we identified a novel disease resistance mutant gene, methyl esterase-like (osmesl) in rice. Mutant rice with T-DNA insertion displayed significant resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo), sheath blight caused by Rhizoctonia solani and rice blast caused by Magnaporthe oryzae. Additionally, CRISPR-Cas9 knockout mutants and RNAi lines displayed resistance to these pathogens. Complementary T-DNA mutants demonstrated a phenotype similar to the wild type (WT), thereby indicating that osmesl confers resistance to pathogens. Protein interaction experiments revealed that OsMESL affects reactive oxygen species (ROS) accumulation by interacting with thioredoxin OsTrxm in rice. Moreover, qRT-PCR results showed significantly reduced mRNA levels of multiple ROS scavenging-related genes in osmesl mutants. Nitroblue tetrazolium staining showed that the pathogens cause ROS accumulation, and quantitative detection revealed significantly increased levels of H2 O2 in the leaves of osmesl mutants and RNAi lines after infection. The abundance of JA, a hormone associated with disease resistance, was significantly more in osmesl mutants than in WT plants. Overall, these results suggested that osmesl enhances disease resistance to Xoo, R. solani and M. oryzae by modulating the ROS balance.

Molecular and Genetic Aspects of Grain Number Determination in Rice (Oryza sativa L.).

Rice grain yield is a complex trait determined by three components: panicle number, grain number per panicle (GNPP) and grain weight. GNPP is the major contributor to grain yield and is crucial for its improvement. GNPP is determined by a series of physiological and biochemical steps, including inflorescence development, formation of rachis branches such as primary rachis branches and secondary rachis branches, and spikelet specialisation (lateral and terminal spikelets). The molecular genetic basis of GNPP determination is complex, and it is regulated by numerous interlinked genes. In this review, panicle development and the determination of GNPP is described briefly, and GNPP-related genes that influence its determination are categorised according to their regulatory mechanisms. We introduce genes related to rachis branch development and their regulation of GNPP, genes related to phase transition (from rachis branch meristem to spikelet meristem) and their regulation of GNPP, and genes related to spikelet specialisation and their regulation of GNPP. In addition, we describe other GNPP-related genes and their regulation of GNPP. Research on GNPP determination suggests that it is possible to cultivate rice varieties with higher grain yield by modifying GNPP-related genes.

Development of 'multiresistance rice' by an assembly of herbicide, insect and disease resistance genes with a transgene stacking system.

BACKGROUND: Weeds, diseases and pests pose serious threats to rice production and cause significant economic losses. Cultivation of rice varieties with resistance to herbicides, diseases and pests is believed to be the most economical and environmentally friendly method to deal with these problems. RESULTS: In this study, a highly efficient transgene stacking system was used to assembly the synthetic glyphosate-tolerance gene (I. variabilis-EPSPS*), lepidopteran pest resistance gene (Cry1C*), brown planthopper resistance genes (Bph14* and OsLecRK1*), bacterial blight resistance gene (Xa23*) and rice blast resistance gene (Pi9*) onto a transformable artificial chromosome vector. The construct was transferred into ZH11 (a widely used japonica rice cultivar Zhonghua 11) via Agrobacterium-mediated transformation and 'multiresistance rice' (MRR) with desirable agronomic traits was obtained. The results showed that MRR had significantly improved resistance to glyphosate, borers, brown planthopper, bacterial blight and rice blast relative to the recipient cultivar ZH11. Besides, under the natural occurrence of pests and diseases in the field, the yield of MRR was significantly higher than that of ZH11. CONCLUSION: A multigene transformation strategy was employed to successfully develop rice lines with multiresistance to glyphosate, borers, brown planthopper, bacterial blight and rice blast, and the obtained MRR is expected to have great application potential. © 2020 Society of Chemical Industry.

Nitrogen Deficiency-Induced Decrease in Cytokinins Content Promotes Rice Seminal Root Growth by Promoting Root Meristem Cell Proliferation and Cell Elongation.

Rice (Oryza sativa L.) seedlings grown under nitrogen (N) deficiency conditions show a foraging response characterized by increased root length. However, the mechanism underlying this developmental plasticity is still poorly understood. In this study, the mechanism by which N deficiency influences rice seminal root growth was investigated. The results demonstrated that compared with the control (1 mM N) treatment, N deficiency treatments strongly promoted seminal root growth. However, the N deficiency-induced growth was negated by the application of zeatin, which is a type of cytokinin (CK). Moreover, the promotion of rice seminal root growth was correlated with a decrease in CK content, which was due to the N deficiency-mediated inhibition of CK biosynthesis through the down-regulation of CK biosynthesis genes and an enhancement of CK degradation through the up-regulation of CK degradation genes. In addition, the N deficiency-induced decrease in CK content not only enhanced the root meristem cell proliferation rate by increasing the meristem cell number via the down-regulation of OsIAA3 and up-regulation of root-expressed OsPLTs, but also promoted root cell elongation by up-regulating cell elongation-related genes, including root-specific OsXTHs and OsEXPs. Taken together, our data suggest that an N deficiency-induced decrease in CK content promotes the seminal root growth of rice seedlings by promoting root meristem cell proliferation and cell elongation.

Strigolactones regulate shoot elongation by mediating gibberellin metabolism and signaling in rice (Oryza sativa L.).

Strigolactones (SLs) are plant hormones that regulate diverse physiological processes including shoot elongation. However, little is known about the regulatory mechanism of SLs in rice shoot elongation. Our results demonstrate that defects in SL biosynthesis or signaling led to dwarfism, and the dwarf statures of SL-deficient mutant (d17) and SL-insensitive mutant (d14) were restored to wild-type (WT) by gibberellin (GA) treatment, indicating that their dwarfism was associated with decreased GA content or weakened GA sensitivity. Our results indicate that the bioactive GA1 contents in d17 and d14 were lower than those in WT, due to the downregulated transcription of GA biosynthesis genes and upregulated transcription of GA inactivation genes. Moreover, d17 and d14 exhibited weakened GA-responsive sensitivity compared with WT. Although the transcription levels of cell division- and cell elongation-related genes were upregulated by GA3 treatment, the increase in transcription of d17 and d14 was lower than that in WT. These results suggest that SL is required for rice shoot elongation by mediating GA metabolism and signaling. Therefore, a deficiency in SL biosynthesis or signaling leads to decreased GA content and weakened GA response, which in turn reduces shoot length by downregulating transcription levels of cell division- and cell elongation-related genes.

Supraoptimal Cytokinin Content Inhibits Rice Seminal Root Growth by Reducing Root Meristem Size and Cell Length via Increased Ethylene Content.

Cytokinins (CKs), a class of phytohormone, regulate root growth in a dose-dependent manner. A certain threshold content of CK is required for rapid root growth, but supraoptimal CK content inhibits root growth, and the mechanism of this inhibition remains unclear in rice. In this study, treatments of lovastatin (an inhibitor of CK biosynthesis) and kinetin (KT; a synthetic CK) were found to inhibit rice seminal root growth in a dose-dependent manner, suggesting that endogenous CK content is optimal for rapid growth of the seminal root in rice. KT treatment strongly increased ethylene level by upregulating the transcription of ethylene biosynthesis genes. Ethylene produced in response to exogenous KT inhibited rice seminal root growth by reducing meristem size via upregulation of OsIAA3 transcription and reduced cell length by downregulating transcription of cell elongation-related genes. Moreover, the effects of KT treatment on rice seminal root growth, root meristem size and cell length were rescued by treatment with aminoethoxyvinylglycine (an inhibitor of ethylene biosynthesis), which restored ethylene level and transcription levels of OsIAA3 and cell elongation-related genes. Supraoptimal CK content increases ethylene level by promoting ethylene biosynthesis, which in turn inhibits rice seminal root growth by reducing root meristem size and cell length.

Salinity Inhibits Rice Seed Germination by Reducing α-Amylase Activity via Decreased Bioactive Gibberellin Content.

Seed germination plays important roles in the establishment of seedlings and their subsequent growth; however, seed germination is inhibited by salinity, and the inhibitory mechanism remains elusive. Our results indicate that NaCl treatment inhibits rice seed germination by decreasing the contents of bioactive gibberellins (GAs), such as GA1 and GA4, and that this inhibition can be rescued by exogenous bioactive GA application. To explore the mechanism of bioactive GA deficiency, the effect of NaCl on GA metabolic gene expression was investigated, revealing that expression of both GA biosynthetic genes and GA-inactivated genes was up-regulated by NaCl treatment. These results suggest that NaCl-induced bioactive GA deficiency is caused by up-regulated expression of GA-inactivated genes, and the up-regulated expression of GA biosynthetic genes might be a consequence of negative feedback regulation of the bioactive GA deficiency. Moreover, we provide evidence that NaCl-induced bioactive GA deficiency inhibits rice seed germination by decreasing α-amylase activity via down-regulation of α-amylase gene expression. Additionally, exogenous bioactive GA rescues NaCl-inhibited seed germination by enhancing α-amylase activity. Thus, NaCl treatment reduces bioactive GA content through promotion of bioactive GA inactivation, which in turn inhibits rice seed germination by decreasing α-amylase activity via down-regulation of α-amylase gene expression.

Jasmonic acid deficiency leads to scattered floret opening time in cytoplasmic male sterile rice Zhenshan 97A.

Cytoplasmic male sterile (CMS) rice has been widely used for hybrid rice seed production in China. However, CMS rice suffers from undesirable flowering habits including scattered floret opening time (FOT), which causes different FOTs among parental rice plants and greatly reduces hybrid rice seed production. Little is known about the mechanism of scattered FOT in CMS rice. Our results demonstrate that scattered FOT in CMS rice Zhenshan 97A (ZS97A) resulted from the lack of a driving force to open florets, which was directly caused by retarded lodicule expansion. Our results indicate that retarded lodicule expansion in ZS97A was caused by reduced water accumulation due to retarded accumulation of osmotic regulation substances (ORSs). Further, the retardation in accumulation of ORSs and water were caused by jasmonic acid (JA) deficiency, resulting from down-regulation of OsAOC expression. Applying JA restored scattered FOT in ZS97A by promoting ORS and water accumulation, and inducing the expansion of the lodicules. Taken together, JA deficiency inhibited lodicule expansion by retarding the accumulation of ORSs and water, leading to scattered FOT in CMS rice ZS97A.

Salicylic acid 3-hydroxylase regulates Arabidopsis leaf longevity by mediating salicylic acid catabolism.

The plant hormone salicylic acid (SA) plays critical roles in plant defense, stress responses, and senescence. Although SA biosynthesis is well understood, the pathways by which SA is catabolized remain elusive. Here we report the identification and characterization of an SA 3-hydroxylase (S3H) involved in SA catabolism during leaf senescence. S3H is associated with senescence and is inducible by SA and is thus a key part of a negative feedback regulation system of SA levels during senescence. The enzyme converts SA (with a Km of 58.29 µM) to both 2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-DHBA in vitro but only 2,3-DHBA in vivo. The s3h knockout mutants fail to produce 2,3-DHBA sugar conjugates, accumulate very high levels of SA and its sugar conjugates, and exhibit a precocious senescence phenotype. Conversely, the gain-of-function lines contain high levels of 2,3-DHBA sugar conjugates and extremely low levels of SA and its sugar conjugates and display a significantly extended leaf longevity. This research reveals an elegant SA catabolic mechanism by which plants regulate SA levels by converting it to 2,3-DHBA to prevent SA overaccumulation. The research also provides strong molecular genetic evidence for an important role of SA in regulating the onset and rate of leaf senescence.

Different effects of night versus day high temperature on rice quality and accumulation profiling of rice grain proteins during grain filling.

High temperature has adverse effects on rice yield and quality. The different influences of night high temperature (NHT) and day high temperature (DHT) on rice quality and seed protein accumulation profiles during grain filling in indica rice '9311' were studied in this research. The treatment temperatures of the control, NHT, and DHT were 28°C/20°C, 27°C/35°C, and 35°C/27°C, respectively, and all the treatments were maintained for 20 days. The result of rice quality analysis indicated that compared with DHT, NHT exerted less effect on head rice rate and chalkiness, whereas greater effect on grain weight. Moreover, the dynamic accumulation change profiles of 61 protein spots, differentially accumulated and successfully identified under NHT and DHT conditions, were performed by proteomic approach. The results also showed that the different suppressed extent of accumulation amount of cyPPDKB might result in different grain chalkiness between NHT and DHT. Most identified isoforms of proteins, such as PPDK and pullulanase, displayed different accumulation change patterns between NHT and DHT. In addition, compared with DHT, NHT resulted in the unique accumulation patterns of stress and defense proteins. Taken together, the mechanisms of seed protein accumulation profiles induced by NHT and DHT during grain filling should be different in rice, and the potential molecular basis is discussed in this study.

Decreased panicle-derived indole-3-acetic acid reduces gibberellin A1 level in the uppermost internode, causing panicle enclosure in male sterile rice Zhenshan 97A.

Cytoplasmic male sterile (CMS) rice Zhenshan 97A (ZS97A) has been widely used in hybrid rice production in China. However, ZS97A suffers from serious panicle enclosure, which blocks normal pollination and greatly reduces seed production of hybrid rice. Little is known about the cause of panicle closure in ZS97A. In this study, it was found that the occurrence of cytoplasmic male sterility caused a deficiency of indole-3-acetic acid (IAA) in ZS97A panicles, and less IAA was provided to the uppermost internode (UI). Further, it was found that the decreased panicle-derived IAA caused a gibberellin A(1) (GA(1)) deficiency in the UI by the down-regulation of OsGA3ox2 transcript level. Reduced GA(1) level in the UI led to decreases of both cell number and cell elongation, resulting in a shortened UI. The shortened UI was unable to push the panicle out of the flag leaf sheath that remained normal, which resulted in panicle enclosure in ZS97A. These findings suggest that decreased panicle-derived IAA reduces the GA(1) level in the UI, causing panicle enclosure in CMS rice ZS97A.

EUI1, encoding a putative cytochrome P450 monooxygenase, regulates internode elongation by modulating gibberellin responses in rice.

Elongation of rice internodes is one of the most important agronomic traits, which determines the plant height and underlies the grain yield. It has been shown that the elongation of internodes is under genetic control, and various factors are implicated in the process. Here, we report a detailed characterization of an elongated uppermost internode1 (eui1) mutant, which has been used in hybrid rice breeding. In the eui1-2 mutant, the cell lengths in the uppermost internodes are significantly longer than that of wild type and thus give rise to the elongated uppermost internode. It was found that the level of active gibberellin was elevated in the mutant, whereas its growth in response to gibberellin is similar to that of the wild type, suggesting that the higher level accumulation of gibberellin in the eui1 mutant causes the abnormal elongation of the uppermost internode. Consistently, the expression levels of several genes which encode gibberellin biosynthesis enzymes were altered. We cloned the EUI1 gene, which encodes a putative cytochrome P450 monooxygenase, by map-based cloning and found that EUI1 was weakly expressed in most tissues, but preferentially in young panicles. To confirm its function, transgenic experiments with different constructs of EUI1 were conducted. Overexpression of EUI1 gave rise to the gibberellin-deficient-like phenotypes, which could be partially reversed by supplementation with gibberellin. Furthermore, apart from the alteration of expression levels of the gibberellin biosynthesis genes, accumulation of SLR1 protein was found in the overexpressing transgenic plants, indicating that the expression level of EUI1 is implicated in both gibberellin-mediated SLR1 destruction and a feedback regulation in gibberellin biosynthesis. Therefore, we proposed that EUI1 plays a negative role in gibberellin-mediated regulation of cell elongation in the uppermost internode of rice.