LINC00624 affects hepatocellular carcinoma proliferation and apoptosis through the miR-342-3p/DNAJC5 axis.

LINC00624 is a long noncoding RNA (lncRNA) which was seldom investigated before. The goal of our study is to clarify the expression and underlying network of LINC00624 in hepatocellular carcinoma (HCC). Here, both HCC and normal living cell lines were employed. Real-time quantitative PCR and western blot were used to determine the pattern of genes and proteins. Colony formation, flow cytometry and western blot tests were used to determine cell proliferation and apoptosis, respectively. Dual luciferase was used to verify molecule-molecule interactions. LINC00624 expression was increased in HCC cell lines and miR-342-3p was decreased. Elimination of LINC00624 increased proliferation while decreasing cell apoptosis. LINC00624 acted as a molecular sponge for miR-342-3p, hence facilitating DNAJC5 expression. Functional tests demonstrated that miR-342-3p suppression could reverse the effect of LINC00624 silence and overexpression of DNAJC5 significantly mitigated the biological consequences of miR-342-3p. These finding demonstrated that LINC00624 aggravated HCC progression by modulating proliferation and apoptosis via targeting miR-342-3p/DNAJC5 axis. These data support that inhibition of LINC00624 may a potential treatment strategies of HCC.

The clinical characteristics of focal acute pancreatitis based on imaging diagnosis: comparison with non-localized acute pancreatitis- a preliminary result.

BACKGROUND: Focal acute pancreatitis is a special type of acute pancreatitis, which diagnosis is based on image showing a focal mass formation in the pancreas. For acute pancreatitis with or without focal inflammatory enlargement, little is known on differences between them. Our purpose was to find differences between focal acute pancreatitis and non-localized acute pancreatitis. METHODS: We reviewed the medical records of a total of 24 patients diagnosed with focal acute pancreatitis by imaging and clinical diagnosis, and 27 cases of acute pancreatitis which manifest non-localized pancreas inflammation were selected as the control group. The differences of the two groups were compared to describe their clinical characteristics. RESULTS: Differences in bloating (4.2% VS 29.6%,P = 0.026), abdominal tenderness (58.3% VS 85.2%,P = 0.032), peripheral blood neutrophil ratio (60.1 ± 23.3VS 75.9 ± 12.6,P = 0.004), serum D-Dimer (0.40(0.25,0.98) VS 1.59(0.49,4.63),P = 0.008), serum GGT (40(25,91) VS120(22,383),P = 0.046), serum amylase(435(241,718) VS 591(394,1333),P = 0.044) and lipase(988(648,1067) VS 1686(525,2675),P = 0.027) between focal acute pancreatitis and non-localized acute pancreatitis groups were statistically significant. However, difference of the severity of two groups was not statistically significant (P = 1.000). CONCLUSION: Compared with non-localized acute pancreatitis, changes in symptoms, signs and laboratory indicators of focal acute pancreatitis are non-obvious, however, there was no significant difference in the severity of two groups, indicating that we should pay more attention to diagnosis of focal acute pancreatitis in clinical practice.

Pathogen manipulation of chloroplast function triggers a light-dependent immune recognition.

In plants and animals, nucleotide-binding leucine-rich repeat (NLR) proteins are intracellular immune sensors that recognize and eliminate a wide range of invading pathogens. NLR-mediated immunity is known to be modulated by environmental factors. However, how pathogen recognition by NLRs is influenced by environmental factors such as light remains unclear. Here, we show that the agronomically important NLR Rpi-vnt1.1 requires light to confer disease resistance against races of the Irish potato famine pathogen Phytophthora infestans that secrete the effector protein AVRvnt1. The activation of Rpi-vnt1.1 requires a nuclear-encoded chloroplast protein, glycerate 3-kinase (GLYK), implicated in energy production. The pathogen effector AVRvnt1 binds the full-length chloroplast-targeted GLYK isoform leading to activation of Rpi-vnt1.1. In the dark, Rpi-vnt1.1-mediated resistance is compromised because plants produce a shorter GLYK-lacking the intact chloroplast transit peptide-that is not bound by AVRvnt1. The transition between full-length and shorter plant GLYK transcripts is controlled by a light-dependent alternative promoter selection mechanism. In plants that lack Rpi-vnt1.1, the presence of AVRvnt1 reduces GLYK accumulation in chloroplasts counteracting GLYK contribution to basal immunity. Our findings revealed that pathogen manipulation of chloroplast functions has resulted in a light-dependent immune response.

Genome-wide analysis and functional characterization of CHYR gene family associated with abiotic stress tolerance in bread wheat (Triticum aestivum L.).

BACKGROUND: CHY zinc-finger and RING finger (CHYR) proteins have been functionally characterized in plant growth, development and various stress responses. However, the genome-wide analysis was not performed in wheat. RESULTS: In this study, a total of 18 TaCHYR genes were identified in wheat and classified into three groups. All TaCHYR genes contained CHY-zinc finger, C3H2C3-type RING finger and zinc ribbon domains, and group III members included 1-3 hemerythrin domains in the N-terminus regions. TaCHYR genes in each group shared similar conserved domains distribution. Chromosomal location, synteny and cis-elements analysis of TaCHYRs were also analyzed. Real-time PCR results indicated that most of selected 9 TaCHYR genes exhibited higher expression levels in leaves during wheat seedling stage. All these TaCHYR genes were up-regulated after PEG treatment, and these TaCHYRs exhibited differential expression patterns in response to salt, cold and heat stress in seedling leaves. The growth of yeast cells expressing TaCHYR2.1, TaCHYR9.2 and TaCHYR11.1 were inhibited under salt and dehydration stress. Moreover, gene ontology (GO) annotation, protein interaction and miRNA regulatory network of TaCHYR genes were analyzed. CONCLUSIONS: These results increase our understanding of CHYR genes and provide robust candidate genes for further functional investigations aimed at crop improvement.

Stress memory gene FaHSP17.8-CII controls thermotolerance via remodeling PSII and ROS signaling in tall fescue.

High temperature is the most limiting factor in the growth of cool-season turfgrass. To cope with high-temperature stress, grass often adopt a memory response by remembering one past recurring stress and preparing a quicker and more robust reaction to the next stress exposure. However, little is known about how stress memory genes regulate the thermomemory response in cool-season turfgrass. Here, we characterized a transcriptional memory gene, Fa-heat shock protein 17.8 Class II (FaHSP17.8-CII) in a cool-season turfgrass species, tall fescue (Festuca arundinacea Schreb.). The thermomemory of FaHSP17.8-CII continued for more than 4 d and was associated with a high H3K4me3 level in tall fescue under heat stress (HS). Furthermore, heat acclimation or priming (ACC)-induced reactive oxygen species (ROS) accumulation and photosystem II (PSII) electron transport were memorable, and this memory response was controlled by FaHSP17.8-CII. In the fahsp17.8-CII mutant generated using CRISPR/Cas9, ACC+HS did not substantially block the ROS accumulation, the degeneration of chloroplast ultra-structure, and the inhibition of PSII activity compared with HS alone. However, overexpression of FaHSP17.8-CII in tall fescue reduced ROS accumulation and chloroplast ultra-structure damage, and improved chlorophyll content and PSII activity under ACC+HS compared with that HS alone. These findings unveil a FaHSP17.8-CII-PSII-ROS module regulating transcriptional memory to enhance thermotolerance in cool-season turfgrass.

Mutation of OsPIN1b by CRISPR/Cas9 Reveals a Role for Auxin Transport in Modulating Rice Architecture and Root Gravitropism.

The distribution and content of auxin within plant tissues affect a variety of important growth and developmental processes. Polar auxin transport (PAT), mainly mediated by auxin influx and efflux transporters, plays a vital role in determining auxin maxima and gradients in plants. The auxin efflux carrier PIN-FORMED (PIN) family is one of the major protein families involved in PAT. Rice (Oryza sativa L.) genome possesses 12 OsPIN genes. However, the detailed functions of OsPIN genes involved in regulating the rice architecture and gravity response are less well understood. In the present study, OsPIN1b was disrupted by CRISPR/Cas9 technology, and its roles in modulating rice architecture and root gravitropism were investigated. Tissue-specific analysis showed that OsPIN1b was mainly expressed in roots, stems and sheaths at the seedling stage, and the transcript abundance was progressively decreased during the seedling stages. Expression of OsPIN1b could be quickly and greatly induced by NAA, indicating that OsPIN1b played a vital role in PAT. IAA homeostasis was disturbed in ospin1b mutants, as evidenced by the changed sensitivity of shoot and root to NAA and NPA treatment, respectively. Mutation of OsPIN1b resulted in pleiotropic phenotypes, including decreased growth of shoots and primary roots, reduced adventitious root number in rice seedlings, as well as shorter and narrower leaves, increased leaf angle, more tiller number and decreased plant height and panicle length at the late developmental stage. Moreover, ospin1b mutants displayed a curly root phenotype cultured with tap water regardless of lighting conditions, while nutrient solution culture could partially rescue the curly root phenotype in light and almost completely abolish this phenotype in darkness, indicating the involvement of the integration of light and nutrient signals in root gravitropism regulation. Additionally, amyloplast sedimentation was impaired in the peripheral tiers of the ospin1b root cap columella cell, while it was not the main contributor to the abnormal root gravitropism. These data suggest that OsPIN1b not only plays a vital role in regulating rice architecture but also functions in regulating root gravitropism by the integration of light and nutrient signals.

The Phytophthora effector Avh94 manipulates host jasmonic acid signaling to promote infection.

The oomycete pathogen Phytophthora sojae is a causal agent of soybean root rot. Upon colonization of soybeans, P. sojae secretes various RXLR effectors to suppress host immune responses, supporting successful infection. Previous research has demonstrated that the RXLR effector Avh94 functions as a virulence effector, but the molecular mechanism underlying its role in virulence remains unknown. Here, we demonstrate that Avh94 overexpression in plants and pathogens promotes Phytophthora infection. Avh94 interacts with soybean JAZ1/2, which is a repressor of jasmonic acid (JA) signaling. Avh94 stabilizes JAZ1/2 to inhibit JA signaling and silencing of JAZ1/2 enhances soybean resistance against P. sojae. Moreover, P. sojae lines overexpressing Avh94 inhibit JA signaling. Furthermore, exogenous application of methyl jasmonate improves plant resistance to Phytophthora. Taken together, these findings suggest that P. sojae employs an RXLR effector to hijack JA signaling and thereby promote infection.

Intragenic heterochromatin-mediated alternative polyadenylation modulates miRNA and pollen development in rice.

Despite a much higher proportion of intragenic heterochromatin-containing genes in crop genomes, the importance of intragenic heterochromatin in crop development remains unclear. Intragenic heterochromatin can be recognised by a protein complex, ASI1-AIPP1-EDM2 (AAE) complex, to regulate alternative polyadenylation. Here, we investigated the impact of rice ASI1 on global poly(A) site usage through poly(A) sequencing and ASI1-dependent regulation on rice development. We found that OsASI1 is essential for rice pollen development and flowering. OsASI1 dysfunction has an important impact on global poly(A) site usage, which is closely related to heterochromatin marks. Intriguingly, OsASI1 interacts with the intronic heterochromatin of OsXRNL, a nuclear XRN family exonuclease gene involved in the processing of an miRNA precursor, to promote the processing of full-length OsXRNL and regulate miRNA abundance. We found that OsASI1-mediated regulation of pollen development partially depends on OsXRNL. Finally, we characterised the rice AAE complex and its involvement in alternative polyadenylation and pollen development. Our findings help to elucidate an epigenetic mechanism governing miRNA abundance and rice development, and provide a valuable resource for studying the epigenetic mechanisms of many important processes in crops.

FaHSP17.8-CII orchestrates lead tolerance and accumulation in shoots via enhancing antioxidant enzymatic response and PSII activity in tall fescue.

Tall fescue (Festuca arundinacea Schreb.) shows huge potential for lead (Pb) phytoremediation, while little is known on the molecular mechanisms involved in Pb tolerance and accumulation. Here, genetic engineering strategy was firstly used to investigate Pb tolerance and accumulation in tall fescue. The transgenic tall fescue overexpressing a class II (CII) sHSP gene FaHSP17.8-CII was generated. After exposure to 1000 mg/L Pb(NO3)2, two FaHSP17.8-CII overexpressing lines, OE#3 and OE#7, showed higher tolerance to Pb as illustrated by the reduced levels of electrolyte leakage (EL) and malondialdehyde (MDA) as compared to the wild-type (WT) plants under Pb stress. Moreover, the FaHSP17.8-CII overexpression lines, OE#3 and OE#7, exhibited 36.3% and 46.6% higher shoot Pb accumulation relative to the WT grasses. When the grasses were exposed to Pb stress, the two OE lines had higher CAT, POD and SOD activities as compared to WT. Additionally, overexpression of FaHSP17.8-CII improved the synthesis of chlorophyll and transcript abundance of FapsbC, FapsbD and FapsbE, and alleviated the photoinhibition of PSII in tall fescue under Pb stress. This study provides an initial genetic engineering strategy to improve Pb phytoremediation efficiency in tall fescue by FaHSP17.8-CII overexpression.

Simultaneous gene editing of three homoeoalleles in self-incompatible allohexaploid grasses.

Clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system has been widely used for precise gene editing in plants. However, simultaneous gene editing of multiple homoeoalleles remains challenging, especially in self-incompatible polyploid plants. Here, we simultaneously introduced targeted mutations in all three homoeoalleles of two genes in the self-incompatible allohexaploid tall fescue, using both CRISPR/Cas9 and LbCas12a (LbCpf1) systems. Loss-of-function mutants of FaPDS exhibited albino leaves, while knockout of FaHSP17.9 resulted in impaired heat resistance in T0 generation of tall fescue. Moreover, these mutations were inheritable. Our findings demonstrate the feasibility of generating loss-of-function mutants in T0 generation polyploid perennial grasses using CRISPR/Cas systems.

Genome-wide small RNA profiling reveals tiller development in tall fescue (Festuca arundinacea Schreb).

BACKGROUND: Tall fescue (Festuca arundinacea Schreb.) is a major cool-season forage and turfgrass species. The low tiller density and size dramatically limits its turf performance and forage yield. MicroRNAs (miRNA)-genes modules play critical roles in tiller development in plants. In this study, a genome-wide small RNA profiling was carried out in two tall fescue genotypes contrasting for tillering production ('Ch-3', high tiller production rate and 'Ch-5', low tiller production rate) and two types of tissue samples at different tillering development stage (Pre-tillering, grass before tillering; Tillering, grass after tillering). 'Ch-3', 'Ch-5', Pre-tillering, and Tillering samples were analyzed using high-throughput RNA sequencing. RESULTS: A total of 222 million high-quality clean reads were generated and 208 miRNAs were discovered, including 148 known miRNAs belonging to 70 families and 60 novel ones. Furthermore, 18 miRNAs were involved in tall fescue tiller development process. Among them, 14 miRNAs displayed increased abundance in both Ch-3 and Tillering plants compared with that in Ch-5 and Pre-tillering plants and were positive with tillering, while another four miRNAs were negative with tiller development. Out of the three miRNAs osa-miR156a, zma-miR528a-3p and osa-miR444b.2, the rest of 15 miRNAs were newfound and associated with tiller development in plants. Based on our previous full-length transcriptome analysis in tall fescue, 28,927 potential target genes were discovered for all identified miRNAs. Most of the 212 target genes of the 18 miRNAs were dominantly enriched into "ubiquitin-mediated proteolysis", "phagosome", "fatty acid biosynthesis", "oxidative phosphorylation", and "biosynthesis of unsaturated fatty acids" KEGG pathways. In addition, bdi-miR167e-3p targets two kinase proteins EIF2AK4 and IRAK4, and osa-miR397a targets auxin response factor 5, which may be the significant miRNA-genes controllers in tillering development. CONCLUSIONS: This is the first genome-wide miRNA profiles analysis to identify regulators involved in tiller development in cool-season turfgrass. Tillering related 18 miRNAs and their 212 target genes provide novel information for the understanding of the molecular mechanisms of miRNA-genes mediated tiller development in cool-season turfgrass.

A protein complex regulates RNA processing of intronic heterochromatin-containing genes in Arabidopsis.

In several eukaryotic organisms, heterochromatin (HC) in the introns of genes can regulate RNA processing, including polyadenylation, but the mechanism underlying this regulation is poorly understood. By promoting distal polyadenylation, the bromo-adjacent homology (BAH) domain-containing and RNA recognition motif-containing protein ASI1 and the H3K9me2-binding protein EDM2 are required for the expression of functional full-length transcripts of intronic HC-containing genes in Arabidopsis Here we report that ASI1 and EDM2 form a protein complex in vivo via a bridge protein, ASI1-Immunoprecipitated Protein 1 (AIPP1), which is another RNA recognition motif-containing protein. The complex also may contain the Pol II CTD phosphatase CPL2, the plant homeodomain-containing protein AIPP2, and another BAH domain protein, AIPP3. As is the case with dysfunction of ASI1 and EDM2, dysfunction of AIPP1 impedes the use of distal polyadenylation sites at tested intronic HC-containing genes, such as the histone demethylase gene IBM1, resulting in a lack of functional full-length transcripts. A mutation in AIPP1 causes silencing of the 35S-SUC2 transgene and genome-wide CHG hypermethylation at gene body regions, consistent with the lack of full-length functional IBM1 transcripts in the mutant. Interestingly, compared with asi1, edm2, and aipp1 mutations, mutations in CPL2, AIPP2, and AIPP3 cause the opposite effects on the expression of intronic HC-containing genes and other genes, suggesting that CPL2, AIPP2, and AIPP3 may form a distinct subcomplex. These results advance our understanding of the interplay between heterochromatic epigenetic modifications and RNA processing in higher eukaryotes.

Crystal structure and luminescence properties of the blue-green-emitting Ba9 (Lu, Y)2 Si6 O24 :Ce3+ phosphor.

Samples of the Ba9 (Lu2-x Yx )Si6 O24 :Ce3+ (x = 0-2) blue-green phosphors were synthesized by solid-state reactions. All the samples exhibited a rhombohedral crystal structure. As the Y3+ concentration increased, the diffraction peaks shifted to the small angle region and the lattice parameters increased due to the larger ionic radius of Y3+ (r = 0.900 Å) compared with that of Lu3+ (r = 0.861 Å). Under 400 nm excitation, samples exhibited strong blue-green emissions around 490 nm. The emission bands had a slight blue shift that resulted from weak crystal-field splitting with increasing Y3+ concentration. Luminescence intensity and quantum efficiency (QE) decreased with increasing Y3+ concentration. The internal QE decreased from 74 to 50% and the external QE decreased from 50 to 34% as x increased from 0 to 2. The thermal stability of the Lu series was better than that of the Y-series. The excitation band peak around 400 nm matched well with the emission light from the efficient near-ultraviolet (NUV) chip. These results indicate promising applications for these NUV-based white light-emitting diodes.

H2O2 Is Involved in the Metallothionein-Mediated Rice Tolerance to Copper and Cadmium Toxicity.

Cadmium (Cd) and excess copper (Cu) are toxic to plants, causing a wide range of deleterious effects including the formation of reactive oxygen species. Metallothioneins (MTs) may protect plant cells from heavy metal toxicity by chelating heavy metals via cysteine thiol groups. They may also function as antioxidants. The study investigated the relationship of H2O2 production and ricMT expression in rice radicles and rice suspension cells under Cu or Cd stress. The results showed that H2O2 production in the rice radicles increased before Cu-induced ricMT expression, and after Cd-induced ricMT expression. Rice suspension cells of sense- and antisense-ricMT transgenic lines were obtained by an Agrobacterium-mediated transformation. Overexpression of ricMT significantly decreased the death rate of rice cells, which was accompanied by blocked H2O2 accumulation in rice suspension cells subject to Cu and Cd stress. Our findings confirm that H2O2 is involved in the MT-mediated tolerance of Cu and Cd toxicity in rice.

Prevalence and risk factors for cirrhotic cardiomyopathy: a prospective cross-sectional study.

BACKGROUND: This study aimed to assess cardiac structure and function in patients with cirrhosis, to investigate the prevalence of cirrhotic cardiomyopathy (CCM) in patients with cirrhosis of different etiologies and to analyze the risk factors for the development of CCM. METHODS: This study selected cirrhotic patients aged 18-75 years who were hospitalized in Qilu Hospital of Shandong University. Patients with known heart disease, chronic lung disease, severe renal insufficiency, malignancy, thyroid disease, hypertension, diabetes or pregnancy were excluded. A total of 131 patients with cirrhosis were finally included. Based on the results of echocardiography, patients who met the diagnostic definition of CCM were included in the CCM group, otherwise, they were classified as the non-CCM group. The demographic and clinical data of the two groups were compared, and the clinical characteristics and risk factors of CCM were evaluated. RESULTS: The overall prevalence of CCM was 24.4%, and the occurrence of CCM was not related to the etiology of liver cirrhosis. The prevalence of CCM was significantly higher among cirrhotic patients complicated with ascites (31.4% vs. 16.4%; P  = 0.046) or with portal vein thrombosis (PVT) (42.9% vs. 17.1%; P  = 0.003). Older age [odds ratio (OR) = 1.058; 95% confidence interval (CI), 1.005-1.113; P  = 0.032] and PVT (OR = 2.999; 95% CI, 1.194-7.533; P  = 0.019) were independent risk factors for the development of CCM. CONCLUSION: The prevalence of CCM in cirrhotic patients was 24.4%, and the occurrence of CCM was not related to the etiology of cirrhosis. The prevalence of CCM was higher in cirrhotic patients with ascites or PVT. Older age and PVT are independent risk factors for CCM, but validation in larger sample studies is still needed.

Associations of cholecystectomy with the risk of gastroesophageal reflux disease: a mendelian randomization study.

BACKGROUND: Cholecystectomy is the standard surgery for patients with gallbladder disease, but the impact of cholecystectomy on gastroesophageal reflux disease (GERD) is not clear. METHODS: We obtained genetic variants associated with cholecystectomy at a genome-wide significant level (P value<5 × 10-8) as instrumental variables (IVs) and performed Mendelian randomization (MR) to explore the relationship with GERD. RESULTS: The Inverse Variance Weighted analysis (IVW) showed that the risk of GERD in patients after cholecystectomy increased (OR=2.19; 95% CI: 1.18 - 4.09). At the same time, the analysis results of weighted median (OR=2.30; 95% CI: 1.51 - 3.48) and weighted mode (OR=2.21; 95% CI: 1.42 - 3.45) were also consistent with the direction of the IVW analysis and were statistically significant (P<0.05). CONCLUSIONS: This study shows that patients who have undergone cholecystectomy are a susceptible population of GERD.

Cloning and Expression Analysis of Key Enzyme Gene CoGPPS Involved in Iridoid Glycoside Synthesis in Cornus officinalis.

Cornus iridoid glycosides (CIGs), including loganin and morroniside, are the main active components of Cornus officinalis. As one of the key enzymes in the biosynthesis of CIGs, geranyl pyrophosphate synthase (GPPS) catalyzes the formation of geranyl pyrophosphate, which is the direct precursor of CIGs. In this study, the C. officinalis geranyl pyrophosphate synthase (CoGPPS) sequence was cloned from C. officinalis and analyzed. The cDNA sequence of the CoGPPS gene was 915 bp (GenBank No. OR725699). Phylogenetic analysis showed that CoGPPS was closely related to the GPPS sequence of Actinidia chinensis and Camellia sinensis, but relatively distantly related to Paeonia lactiflora and Tripterygium wilfordii. Results from the quantitative real-time PCR showed the spatiotemporal expression pattern of CoGPPS; that is, CoGPPS was specifically expressed in the fruits. Subcellular localization assay proved that CoGPPS was specifically found in chloroplasts. Loganin and morroniside contents in the tissues were detected by high-performance liquid chromatography, and both compounds were found to be at higher levels in the fruits than in leaves. Thus, this study laid the foundation for further studies on the synthetic pathway of CIGs.

Overexpression of OsPIN9 Impairs Chilling Tolerance via Disturbing ROS Homeostasis in Rice.

The auxin efflux transporter PIN-FORMED (PIN) family is one of the major protein families that facilitates polar auxin transport in plants. Here, we report that overexpression of OsPIN9 leads to altered plant architecture and chilling tolerance in rice. The expression profile analysis indicated that OsPIN9 was gradually suppressed by chilling stress. The shoot height and adventitious root number of OsPIN9-overexpressing (OE) plants were significantly reduced at the seedling stage. The roots of OE plants were more tolerant to N-1-naphthylphthalamic acid (NPA) treatment than WT plants, indicating the disturbance of auxin homeostasis in OE lines. The chilling tolerance assay showed that the survival rate of OE plants was markedly lower than that of wild-type (WT) plants. Consistently, more dead cells, increased electrolyte leakage, and increased malondialdehyde (MDA) content were observed in OE plants compared to those in WT plants under chilling conditions. Notably, OE plants accumulated more hydrogen peroxide (H2O2) and less superoxide anion radicals (O2-) than WT plants under chilling conditions. In contrast, catalase (CAT) and superoxide dismutase (SOD) activities in OE lines decreased significantly compared to those in WT plants at the early chilling stage, implying that the impaired chilling tolerance of transgenic plants is probably attributed to the sharp induction of H2O2 and the delayed induction of antioxidant enzyme activities at this stage. In addition, several OsRboh genes, which play a crucial role in ROS production under abiotic stress, showed an obvious increase after chilling stress in OE plants compared to that in WT plants, which probably at least in part contributes to the production of ROS under chilling stress in OE plants. Together, our results reveal that OsPIN9 plays a vital role in regulating plant architecture and, more importantly, is involved in regulating rice chilling tolerance by influencing auxin and ROS homeostasis.

Deficiency of Auxin Efflux Carrier OsPIN1b Impairs Chilling and Drought Tolerance in Rice.

Significant progress has been made in the functions of auxin efflux transporter PIN-FORMED (PIN) genes for the regulation of growth and development in rice. However, knowledge on the roles of OsPIN genes in abiotic stresses is limited. We previously reported that the mutation of OsPIN1b alters rice architecture and root gravitropism, while the role of OsPIN1b in the regulation of rice abiotic stress adaptations is still largely elusive. In the present study, two homozygous ospin1b mutants (C1b-1 and C1b-2) were employed to investigate the roles of OsPIN1b in regulating abiotic stress adaptations. Low temperature gradually suppressed OsPIN1b expression, while osmotic stress treatment firstly induced and then inhibited OsPIN1b expression. Most OsPIN genes and auxin biosynthesis key genes OsYUC were up-regulated in ospin1b leaves, implying that auxin homeostasis is probably disturbed in ospin1b mutants. The loss of function of OsPIN1b significantly decreased rice chilling tolerance, which was evidenced by decreased survival rate, increased death cells and ion leakage under chilling conditions. Compared with the wild-type (WT), ospin1b mutants accumulated more hydrogen peroxide (H2O2) and less superoxide anion radicals (O2-) after chilling treatment, indicating that reactive oxygen species (ROS) homeostasis is disrupted in ospin1b mutants. Consistently, C-repeat binding factor (CBF)/dehydration-responsive element binding factor (DREB) genes were downregulated in ospin1b mutants, implying that OsDREB genes are implicated in OsPIN1b-mediated chilling impairment. Additionally, the mutation of OsPIN1b led to decreased sensitivity to abscisic acid (ABA) treatment in seed germination, impaired drought tolerance in the seedlings and changed expression of ABA-associated genes in rice roots. Taken together, our investigations revealed that OsPIN1b is implicated in chilling and drought tolerance in rice and provide new insight for improving abiotic stress tolerance in rice.