Analysis for variable manifestations and molecular characteristics of pyridox(am)ine-5'-phosphate oxidase (PNPO) deficiency.

BACKGROUND: To summarize the clinical and genetic characteristics of patients with pyridox(am)ine-5'-phosphate oxidase (PNPO) deficiency. METHODS: Clinical and genetic data of the patients were collected and analyzed. RESULTS: Eighteen patients from 17 families with variants in PNPO were collected, and 15 cases survived to date. The age of onset ranged from 1 day to 5 months (median age 6.5 days) and seven of them presented with seizures <24 h. About 7/18 (39%) of patients showed seizure-free with pyridoxine (PN) or pyridoxal-5'-phosphate treatment. Two patients showed surprised therapeutic responses to antiseizure medications therapy: one could be controlled for up to 1 year and 5 months, and the other showed seizure-free for >8 years. The neurodevelopment was normal in one patient, mild delay in four, in whom responded well to PN. Severe delay could be seen in the remaining 10 surviving patients. Genetic analysis revealed 14 variants of PNPO, seven of which were novel. Five pairs of unrelated patients were observed to carry the same variants, respectively, and had similar developmental status and onset age of seizures in some degree in each pair, whereas also had differences. CONCLUSIONS: The clinical characteristics, including age of onset, treatment response and prognosis, were variable and difficult to classify into different types clearly. Patients with PNPO deficiency who used PN as their main treatment and being able to control seizures seemed to be associated with better outcomes. Patients with the same genotype tended to show the correlation of phenotype-genotype.

Knockout of the sugar transporter OsSTP15 enhances grain yield by improving tiller number due to increased sugar content in the shoot base of rice (Oryza sativa L.).

Sugar transporter proteins (STPs) play critical roles in regulating plant stress tolerance, growth, and development. However, the role of STPs in regulating crop yield is poorly understood. This study elucidates the mechanism by which knockout of the sugar transporter OsSTP15 enhances grain yield via increasing the tiller number in rice. We found that OsSTP15 is specifically expressed in the shoot base and vascular bundle sheath of seedlings and encodes a plasma membrane-localized high-affinity glucose efflux transporter. OsSTP15 knockout enhanced sucrose and trehalose-6-phosphate (Tre6P) synthesis in leaves and improved sucrose transport to the shoot base by inducing the expression of sucrose transporters. Higher glucose, sucrose, and Tre6P contents were observed at the shoot base of stp15 plants. Transcriptome and metabolome analyses of the shoot base demonstrated that OsSTP15 knockout upregulated the expression of cytokinin (CK) synthesis- and signaling pathway-related genes and increased CK levels. These findings suggest that OsSTP15 knockout represses glucose export from the cytoplasm and simultaneously enhances sugar transport from source leaves to the shoot base by promoting the synthesis of sucrose and Tre6P in leaves. Subsequent accumulation of glucose, sucrose, and Tre6P in the shoot base promotes tillering by stimulating the CK signaling pathway.

CHLORIDE CHANNEL-b mediates vacuolar nitrate efflux to improve low nitrogen adaptation in Arabidopsis.

The vacuole is an important organelle for nitrate storage, and the reuse of vacuolar nitrate under nitrate starvation helps plants adapt to low-nitrate environments. CHLORIDE CHANNEL-b (CLC-b) in the vacuolar membrane is a nitrate transporter; however, its regulation and effects on nitrate efflux have not been established. Here, we evaluated CLC-b expression and its effects on physiological parameters under low nitrate conditions. CLC-b expression increased significantly in the roots of wild-type Arabidopsis (Arabidopsis thaliana) Col-0 under nitrate starvation. Under low nitrate, clcb mutants showed reductions in chlorophyll content and xylem sap nitrate concentration, shoot/root nitrate ratios, shoot/root total N ratios, and biomass. CLC-b-overexpression yielded opposite phenotypes and increased nitrogen use efficiency. CLC-b mutants showed elevated chlorate tolerance and an increased proportion of vacuolar nitrate relative to the total protoplast nitrate content as compared to the wild type. Yeast 1-hybrid, EMSA, and chromatin immunoprecipitation (ChIP) experiments showed that HRS1 HOMOLOG2 (HHO2), the expression of which is downregulated under low nitrate, binds directly to the promoter of CLC-b. clcb/hho2 double mutants and HHO2-overexpressing clcb plants had similar phenotypes under low nitrate to those of clcb single mutants. Thus, CLC-b mediates vacuolar nitrate efflux and is negatively regulated by HHO2, providing a theoretical basis for improving plant adaptability to low nitrate.

Geminivirus C5 proteins mediate formation of virus complexes at plasmodesmata for viral intercellular movement.

Movement proteins (MPs) encoded by plant viruses deliver viral genomes to plasmodesmata (PD) to ensure intracellular and intercellular transport. However, how the MPs encoded by monopartite geminiviruses are targeted to PD is obscure. Here, we demonstrate that the C5 protein of tomato yellow leaf curl virus (TYLCV) anchors to PD during the viral infection following trafficking from the nucleus along microfilaments in Nicotiana benthamiana. C5 could move between cells and partially complement the traffic of a movement-deficient turnip mosaic virus (TuMV) mutant (TuMV-GFP-P3N-PIPO-m1) into adjacent cells. The TYLCV-C5 null mutant (TYLCV-mC5) attenuates viral pathogenicity and decreases viral DNA and protein accumulation, and ectopic overexpression of C5 enhances viral DNA accumulation. Interaction assays between TYLCV-C5 and the other eight viral proteins described in TYLCV reveal that C5 associates with C2 in the nucleus and with V2 in the cytoplasm and at PD. The V2 protein is mainly localized in the nucleus and cytoplasmic granules when expressed alone; in contrast, V2 forms small punctate granules at PD when co-expressed with C5 or in TYLCV-infected cells. The interaction of V2 and C5 also facilitates their nuclear export. Furthermore, C5-mediated PD localization of V2 is conserved in two other geminiviruses. Therefore, this study solves a long-sought-after functional connection between PD and the geminivirus movement and improves our understanding of geminivirus-encoded MPs and their potential cellular and molecular mechanisms.

Selective autophagic receptor NbNBR1 prevents NbRFP1-mediated UPS-dependent degradation of ßC1 to promote geminivirus infection.

Autophagy is an evolutionarily conserved, lysosomal/vacuolar degradation mechanism that targets cell organelles and macromolecules. Autophagy and autophagy-related genes have been studied for their antiviral and pro-viral roles in virus-infected plants. Here, we demonstrate the pro-viral role of a selective autophagic receptor NbNBR1 in geminivirus-infected Nicotiana benthamiana plants. The ßC1 protein encoded by tomato yellow leaf curl China betasatellite (TYLCCNB) that is associated with tomato yellow leaf curl China virus (TYLCCNV) enhanced the expression level of NbNBR1. Then NbNBR1 interacted with ßC1 to form cytoplasmic granules. Interaction of NbNBR1 with ßC1 could prevent degradation of ßC1 by the NbRFP1, an E3 ligase. Overexpression of NbNBR1 in N. benthamiana plants increased ßC1 accumulation and promoted virus infection. In contrast, silencing or knocking out NbNBR1 expression in N. benthamiana suppressed ßC1 accumulation and inhibited virus infection. A single amino acid substitution in ßC1 (ßC1K4A) abolished its interaction with NbNBR1, leading to a reduced level of ßC1K4A. The TYLCCNV/TYLCCNBK4A mutant virus caused milder disease symptoms and accumulated much less viral genomic DNAs in the infected plants. Collectively, the results presented here show how a viral satellite-encoded protein hijacks host autophagic receptor NbNBR1 to form cytoplasmic granules to protect itself from NbRFP1-mediated degradation and facilitate viral infection.

SAMBA controls cell division rate during maize development.

SAMBA has been identified as a plant-specific regulator of the anaphase-promoting complex/cyclosome (APC/C) that controls unidirectional cell cycle progression in Arabidopsis (Arabidopsis thaliana), but so far its role has not been studied in monocots. Here, we show the association of SAMBA with the APC/C is conserved in maize (Zea mays). Two samba genome edited mutants showed growth defects, such as reduced internode length, shortened upper leaves with erect leaf architecture, and reduced leaf size due to an altered cell division rate and cell expansion, which aggravated with plant age. The two mutants differed in the severity and developmental onset of the phenotypes, because samba-1 represented a knockout allele, while translation re-initiation in samba-3 resulted in a truncated protein that was still able to interact with the APC/C and regulate its function, albeit with altered APC/C activity and efficiency. Our data are consistent with a dosage-dependent role for SAMBA to control developmental processes for which a change in growth rate is pivotal.

Compilation and evaluation of gastrointestinal endoscopy satisfaction scale. / æ¶ˆåŒ–å† é•œè¯Šç–—æ»¡æ„åº¦é‡è¡¨çš„ç¼–åˆ¶åŠè¯„ä»·.

OBJECTIVES: Gastrointestinal endoscopy plays an important role in the diagnosis and treatment of gastrointestinal diseases. The satisfaction degree of gastrointestinal endoscopy can directly affect the patient's compliance and further impact the treating effect. At present, there is no scale to evaluate the satisfaction degree of gastrointestinal endoscopy in China. This study aims to develop a satisfaction scale of gastrointestinal endoscopy suitable for national conditions and to evaluate its reliability and validity, which provides a tool for clinic to evaluate patients' satisfaction with gastrointestinal endoscopy. METHODS: The original gastrointestinal endoscopy satisfaction scale was compiled by literature review, consulting senior endoscopists and experts. Through the first round of survey about 120 patients, the original scale was analyzed and modified according to the results to get the gastrointestinal endoscopy satisfaction scale (formal scale). The formal scale was used to conduct the second round of survey about 200 patients. The reliability and validity of the scale were analyzed and evaluated according to the survey results. RESULTS: The reliability of the original scale was good but the validity was poor. The formal scale had 2 dimensions and 10 items, the Cronbach's alpha and split-half reliability were 0.889 and 0.823. The structure validity index χ2/df was 2.513, root mean square error of approximation (RMSEA) was 0.094, goodness of fit index (GFI) was 0.914, adjusted goodness of fit index (AGFI) was 0.861, comparative fit index (CFI) was 0.946, normed fit index (NFI) was 0.915. The aggregate validity was general, the discriminative validity was good, and the direct score of patients was strongly correlated with the total score of the scale. CONCLUSIONS: The gastrointestinal endoscopy satisfaction scale has good reliability and validity, which can be used as a tool to evaluate patients' satisfaction with gastrointestinal endoscopy in China.

Development and evaluation of acceptance scale for artificial intelligence in digestive endoscopy by subjects. / å—æ£€è€ å¯¹æ¶ˆåŒ–å† é•œäººå·¥æ™ºèƒ½æŽ¥å—åº¦é‡è¡¨çš„ç¼–åˆ¶åŠè¯„ä»·.

OBJECTIVES: Digestive endoscopy is an important diagnostic and therapeutic tool for digestive system diseases. The artificial intelligence (AI)-assisted system in endoscopy (hereinafter referred to as AI in digestive endoscopy) has broad application prospects in the field of digestive endoscopy. The trust and acceptance of endoscopic subjects are the cornerstone of the research, application, and promotion of AI in digestive endoscopy. Currently, the tools for measuring the acceptance of AI in digestive endoscopy by subjects are limited at home and abroad. This study aims to develop a scale for measuring the acceptance of AI in digestive endoscopy by subjects, then to evaluate its reliability and validity. METHODS: By conducting literature research, an item pool and dimensions were constructed, and a preliminary scale was constructed using Delphi method. Through the first stage of the survey on the subjects, the reliability and validity of the scale were tested, and the revised scale was used for the second stage of survey on the subjects to further verify the structural validity of the scale. RESULTS: The acceptance scale for AI in digestive endoscopy included 11 items in 3 dimensions: accuracy, ethics, benefit and willingness. In the first stage of the survey, 351 valid questionnaires were collected, and the Cronbach's α was 0.864. The correlation coefficient between the total score of the scale and the score of the test item was 0.636, and the Kaiser-Meyer-Olkin (KMO) value in exploratory factor analysis was 0.788. In the second stage of the survey, 335 valid questionnaires were collected, and in confirmatory factor analysis, the χ2/df was 3.774, while the root mean squared error of approximation (RMSEA) was 0.091. CONCLUSIONS: Acceptance scale for AI in digestive endoscopy by subjects developed in this study has good reliability and validity.

Novel biallelic loss of EEF1B2 function links to autosomal recessive intellectual disability.

Biallelic variants in EEF1B2 have recently been shown to cause a novel form of non-syndromic intellectual disability (ID) in two unrelated families. More patients are needed to delineate the genotypic and phenotypic spectrum of this gene. In this study, two patients in a family harboring pathogenic compound heterozygous variants in EEF1B2 were identified. They were characterized by non-syndromic ID and fever-sensitive seizures in childhood. Quantitative real-time polymerase chain reaction (QPCR) analysis showed significantly reduced levels of mRNA expression in two patients compared with unaffected controls. The level of EEF1B2 protein was hardly detected in both patients and their unaffected parents. The eef1b2 F0 knockout (crispant) zebrafish presented with abnormal development and light-induced hyperactivity. We identified novel pathogenic EEF1B2 variants within two siblings in a new family. The findings of the expression experiment and first crispant eef1b2 zebrafish model provided further clues to the role of EEF1B2 variants in the pathogenesis of autosomal-recessive ID.

De novo variants in AGO1 recapitulate a heterogeneous neurodevelopmental disorder phenotype.

AGO1, as one of the rare genes in neurodevelopmental disorders, is involved in the microRNA-induced silencing complex. Here, we describe the clinical and genetic features of 18 individuals with de novo AGO1 variants: four new and 14 previously reported. Three variants are identified: two in-frame deletion variants and one missense variant. The spectrum of AGO1-related disorders included global development delay (GDD), intellectual disability (ID) with or without epilepsy, autism spectrum disorder, hypotonia and dysmorphisms. Focal seizures are the most common type of seizure, occasionally with atypical absence. Mild deafness may be a new phenotype of AGO1-releated disease. Gly199Ser may be a hot-spot variant of AGO1 with the same phenotype: GDD/ID, intractable epilepsy, remarkably with Rolandic discharges, and even reaching electrical status epilepticus during sleep.

Can visceral adipose tissue and skeletal muscle predict recurrence of newly diagnosed Crohn's disease in different treatments.

BACKGROUND AND AIMS: It is crucial to manage the recurrence of Crohn's disease (CD). This study is aimed to explore whether visceral adipose tissue (VAT) and skeletal muscle (SM) are associated with the recurrence of CD upon different treatments. METHODS: All patients with a definite diagnosis of CD were retrospectively divided into three groups according to distinct treatment regimens: 5-amino salicylic acid group (Group A), steroids + azathioprine (Group B) and biologics (Group C). The pretreatment computerized tomography (CT) images and clinical data were collected. The VAT area, mesenteric fat index (MFI), the ratio of VAT area to fat mass (VAT area/FM) were assessed. The primary end point was the recurrence of CD within 1 year of follow-up. RESULTS: A total of 171 CD patients were enrolled, including 57 (33.33%) patients in Group A, 70 (40.94%) patients in Group B and 44 (25.73%) patients in Group C. Patients with 1-year recurrence had higher MFI (P = 0.011) and VAT area/FM (P = 0.000). ROC curve demonstrated that patients with the ratio of VAT area/FM and MFI higher than 0.578 and 1.394 tended to have recurrence with the AUC of 0.707 and 0.709. Similar results could be observed in Group A & B but not in Group C. CONCLUSIONS: High VAT area/FM and MFI are related to recurrence within 1 year for newly diagnosed CD patients treated by 5-amino salicylic or azathioprine + steroids rather than biologics. We could not observe any radiological data associated with the recurrence of CD patients under biological treatment.

Phenotype of heterozygous variants of dehydrodolichol diphosphate synthase.

AIM: To further identify and broaden the phenotypic characteristics and genotype spectrum of the dehydrodolichol diphosphate synthase (DHDDS) gene. METHOD: Pathogenic variants of DHDDS were identified by whole-exome sequencing; clinical data of 10 patients (six males, four females; age range 2-14y; mean age 5y 9mo, SD 3y 3mo) were collected and analysed. RESULTS: All patients had seizures, and myoclonic seizures could be seen in eight patients, with myoclonic status epilepticus in three. The interictal electroencephalogram (EEG) in four patients at seizure onset showed generalized slow waves, slow wave mixed spikes, and spike and waves. Tremor, ataxia, and hypertonia was observed in six, five, and three patients respectively. The results of short-latency somatosensory evoked potential in two patients were normal, and the symptom of tremor was captured on EEG without time-locked discharges in one patient, suggesting that the tremor in both patients was a motor impairment rather than myoclonic seizures. Global developmental delay occurred in all patients, among whom nine showed severe intellectual disability and one moderate. Five DHDDS variants were identified, three of which have not been reported previously. INTERPRETATION: Myoclonic seizure is the most common seizure type in heterozygous DHDDS variants, while myoclonic status epilepticus can also occur. The pattern of interictal EEG discharges is characterized by slow waves rather than spike and waves, and generalized discharges was prominent.

Knockdown of hsa_circ_0043691 restrains the progression of gastric cancer by decoying miR-1294 to target pre-leukemia transcription factor 3.

BACKGROUND: Circular RNAs (circRNAs) have been found to render pivotal effects in gastric cancer (GC). However, the effect of hsa_circ_0043691 in GC still needs to be further unveiled. METHODS: The contents of hsa_circ_0043691, miR-1294, and pre-leukemia transcription factor 3 (PBX3) were examined using qRT-PCR or Western blot assay. In vitro colony formation, transwell, wound healing, flow cytometry, tube formation assays, glutaminolysis corresponding kit and in vivo Xenograft mice model were utilized to evaluate cell functions. The relationship between miR-1294 and hsa_circ_0043691 or PBX3 was further verified. RESULTS: The levels of hsa_circ_0043691 and PBX3 were upregulated, whereas miR-1294 expression was diminished in GC tissues and cells. Hsa_circ_0043691 deficiency significantly inhibited GC cell progression and glutaminolysis metabolism. Mechanistically, hsa_circ_0043691 was directly bound to miR-1294 to modulate PBX3 expression. Besides, silencing of hsa_circ_0043691 impeded tumor growth in vivo. CONCLUSION: Hsa_circ_0043691 knockdown repressed GC malignant phenotypes by miR-1294/PBX3 axis, which exhibited a novel therapeutic target for GC treatment.

Nuclear exportin 1 facilitates turnip mosaic virus infection by exporting the sumoylated viral replicase and by repressing plant immunity.

Exportin 1/XPO1 is an important nuclear export receptor that binds directly to cargo proteins and translocates the cargo proteins to the cytoplasm. To understand XPO1 protein functions during potyvirus infections, we investigated the nuclear export of the NIb protein encoding the RNA-dependent RNA polymerase (RdRp) of turnip mosaic virus (TuMV). Previously, we found that NIb is transported to the nucleus after translation and sumoylated by the sumoylation (small ubiquitin-like modifier) pathway to support viral infection. Here, we report that XPO1 interacts with NIb to facilitate translocation from the nucleus to the viral replication complexes (VRCs) that accumulate in the perinuclear regions of TuMV-infected cells. XPO1 contains two NIb-binding domains that recognize and interact with NIb in the nucleus and in the perinuclear regions, respectively, which facilitates TuMV replication. Moreover, XPO1 is involved in nuclear export of the sumoylated NIb and host factors tagged with SUMO3 that is essential for suppression of plant immunity in the nucleus. Deficiencies of XPO1 in Arabidopsis and Nicotiana benthamiana plants inhibit TuMV replication and infection. These data demonstrate that XPO1 functions as a host factor in TuMV infection by regulating NIb nucleocytoplasmic transport and plant immunity.

Computationally Efficient Direction-of-Arrival Estimation Algorithms for a Cubic Coprime Array.

In this paper, we investigate the problem of direction-of-arrival (DOA) estimation for massive multi-input multi-output (MIMO) radar, and propose a total array-based multiple signals classification (TA-MUSIC) algorithm for two-dimensional direction-of-arrival (DOA) estimation with a coprime cubic array (CCA). Unlike the conventional multiple signal classification (MUSIC) algorithm, the TA-MUSIC algorithm employs not only the auto-covariance matrix but also the mutual covariance matrix by stacking the received signals of two sub cubic arrays so that full degrees of freedom (DOFs) can be utilized. We verified that the phase ambiguity problem can be eliminated by employing the coprime property. Moreover, to achieve lower complexity, we explored the estimation of signal parameters via the rotational invariance technique (ESPRIT)-based multiple signal classification (E-MUSIC) algorithm, which uses a successive scheme to be computationally efficient. The Cramer-Rao bound (CRB) was taken as a theoretical benchmark for the lower boundary of the unbiased estimate. Finally, numerical simulations were conducted in order to demonstrate the effectiveness and superiority of the proposed algorithms.

Unveiling the Complexity of Red Clover (Trifolium pratense L.) Transcriptome and Transcriptional Regulation of Isoflavonoid Biosynthesis Using Integrated Long- and Short-Read RNAseq.

Red clover (Trifolium pratense L.) is used as forage and contains a high level of isoflavonoids. Although isoflavonoids in red clover were discovered a long time ago, the transcriptional regulation of isoflavonoid biosynthesis is virtually unknown because of the lack of accurate and comprehensive characterization of the transcriptome. Here, we used a combination of long-read (PacBio Iso-Seq) and short-read (Illumina) RNAseq sequencing to develop a more comprehensive full-length transcriptome in four tissues (root, stem, leaf, and flower) and to identify transcription factors possibly involved in isoflavonoid biosynthesis in red clover. Overall, we obtained 50,922 isoforms, including 19,860 known genes and 2817 novel isoforms based on the annotation of RefGen Tp_v2.0. We also found 1843 long non-coding RNAs, 1625 fusion genes, and 34,612 alternatively spliced events, with some transcript isoforms validated experimentally. A total of 16,734 differentially expressed genes were identified in the four tissues, including 43 isoflavonoid-biosynthesis-related genes, such as stem-specific expressed TpPAL, TpC4H, and Tp4CL and root-specific expressed TpCHS, TpCHI1, and TpIFS. Further, weighted gene co-expression network analysis and a targeted compound assay were combined to investigate the association between the isoflavonoid content and the transcription factors expression in the four tissues. Twelve transcription factors were identified as key genes for isoflavonoid biosynthesis. Among these transcription factors, the overexpression of TpMYB30 or TpRSM1-2 significantly increased the isoflavonoid content in tobacco. In particular, the glycitin was increased by 50-100 times in the plants overexpressing TpRSM1-2, in comparison to that in the WT plants. Our study provides a comprehensive and accurate annotation of the red clover transcriptome and candidate genes to improve isoflavonoid biosynthesis and accelerate research into molecular breeding in red clover or other crops.

Clinical and genetic features in pyridoxine-dependent epilepsy: a Chinese cohort study.

AIM: To characterize the clinical and genetic characteristics of a large cohort of patients with pyridoxine-dependent epilepsy (PDE). METHOD: We retrospectively collected clinical and genetic information of 33 (15 males, 18 females; mean [SD] age 4y 11mo [2y 5mo]; 1y 3mo-10y 4mo) patients with PDE from 31 unrelated families at a single centre. RESULTS: There were many types of seizures, with focal seizures in 32 cases. Dravet syndrome was suspected clinically in two patients. Electroencephalogram (EEG) was normal in seven patients at the initial stage and then in 17 patients during pyridoxine maintenance therapy. Genetic studies revealed 26 kinds of variants in ALDH7A1 and four in PLPBP with 18 variants unreported previously, and 48 ALDH7A1 variants were located in exon 11, 12, 14, and 17 or intron 9 and 11. In addition, three patients carried different exons deletion. Among these, seizures could be controlled for several years in one patient by levetiracetam monotherapy. Another patient remained seizure free for up to 7 months without therapy. All patients received oral pyridoxine treatment, with only one case (with exon 8-13 deletion) showing poor control. INTERPRETATION: This study illustrates the range of clinical presentations and genetic causes in PDE, as well as responsiveness to antiepileptic drugs. A relationship between EEG and pyridoxine therapy could be seen in many cases. Seizure control was seen in all with pyridoxine monotherapy except for one patient. WHAT THIS PAPER ADDS: There is a parallel relationship between electroencephalogram and pyridoxine therapy in many patients. Patients with pyridoxine-dependent epilepsy may respond well to low-dose pyridoxine.

Disruption of a Upf1-like helicase-encoding gene OsPLS2 triggers light-dependent premature leaf senescence in rice.

KEY MESSAGE: The OsPLS2 locus was isolated and cloned by map-based cloning that encodes a Upf1-like helicase. Disruption of OsPLS2 accelerated light-dependent leaf senescence in the rice mutant of ospls2. Leaf senescence is a very complex physiological process controlled by both genetic and environmental factors, however its underlying molecular mechanisms remain elusive. In this study, we report a novel Oryza sativa premature leaf senescence mutant (ospls2). Through map-based cloning, a G-to-A substitution was determined at the 1st nucleotide of the 13th intron in the OsPLS2 gene that encodes a Upf1-like helicase. This mutation prompts aberrant splicing of OsPLS2 messenger and consequent disruption of its full-length protein translation, suggesting a negative role of OsPLS2 in regulating leaf senescence. Wild-type rice accordingly displayed a progressive drop of OsPSL2 protein levels with age-dependent leaf senescence. Shading and light filtration studies showed that the ospls2 phenotype, which was characteristic of photo-oxidative stress and reactive oxygen species (ROS) accumulation, was an effect of irritation by light. When continuously exposed to far-red light, exogenous H2O2 and/or abscisic acid (ABA), the ospls2 mutant sustained hypersensitive leaf senescence. In consistence, light and ROS signal pathways in ospls2 were activated by down-regulation of phytochrome genes, and up-regulation of PHYTOCHROME-INTERACTING FACTORS (PIFs) and WRKY genes, all promoting leaf senescence. Together, these data indicated that OsPLS2 played an essential role in leaf senescence and its disruption triggered light-dependent leaf senescence in rice.

Development and application of EST-SSRs markers for analysis of genetic diversity in erect milkvetch (Astragalus adsurgens Pall.).

Erect milkvetch (Astragalus adsurgens Pall.) is a major legume forage plant widely grown in Northern China. However, the lack of molecular markers has limited its research into its genetic diversity and work on germplasm improvement. In this study, a total of 39,163 EST-SSR loci were identified from 30,262 unigene sequences in the erect milkvetch transcriptome using Illumina sequencing. Moreover, 22,367 EST-SSR primer pairs (PPs) were successfully designed. In addition, 100 PPs were synthesized and preliminarily screened in two accessions; of these, 90 were determined to be clear and stable EST-SSR markers. Fifty-one PPs were randomly selected in order to assess the genetic diversity of 27 erect milkvetch accessions. The average polymorphism information content of the 51 PPs was 0.682. Greater genetic diversity was detected in accessions from Inner Mongolia and in the group of landrace and wild erect milkvetch accessions. This study provides an important resource for germplasm improvement and genetic diversity analysis in erect milkvetch.