Evaluation of novel promoters for vascular tissue-specific gene expression in Populus.

Due to the extended generation cycle of trees, the breeding process for forest trees tends to be time-consuming. Genetic engineering has emerged as a viable approach to expedite the genetic breeding of forest trees. However, current genetic engineering techniques employed in forest trees often utilize continuous expression promoters such as CaMV 35S, which may result in unintended consequences by introducing genes into non-target tissues. Therefore, it is imperative to develop specific promoters for forest trees to facilitate targeted and precise design and breeding. In this study, we utilized single-cell RNA-Seq data and co-expression network analysis during wood formation to identify three vascular tissue-specific genes in poplar, PP2-A10, PXY, and VNS07, which are expressed in the phloem, cambium/expanding xylem, and mature xylem, respectively. Subsequently, we cloned the promoters of these three genes from '84K' poplar and constructed them into a vector containing the eyGFPuv visual selection marker, along with the 35S mini enhancer to drive GUS gene expression. Transgenic poplars expressing the ProPagPP2-A10::GUS, ProPagPXY::GUS, and ProPagVNS07::GUS constructs were obtained. To further elucidate the tissue specificity of these promoters, we employed qPCR, histochemical staining, and GUS enzyme activity. Our findings not only establish a solid foundation for the future utilization of these promoters to precisely express of specific functional genes in stems but also provide a novel perspective for the modular breeding of forest trees.

PagPXYs improve drought tolerance by regulating reactive oxygen species homeostasis in the cambium of Populus alba × P. glandulosa.

PXY (Phloem intercalated with xylem) is a receptor kinase required for directional cell division during the development of plant vascular tissue. Drought stress usually affects plant stem cell division and differentiation thereby limiting plant growth. However, the role of PXY in cambial activities of woody plants under drought stress is unclear. In this study, we analyzed the biological functions of two PXY genes (PagPXYa and PagPXYb) in poplar growth and development and in response to drought stress in a hybrid poplar (Populus alba × P. glandulosa, '84K'). Expression analysis indicated that PagPXYs, similar to their orthologs PtrPXYs in Populus trichocarpa, are mainly expressed in the stem vascular system, and related to drought. Interestingly, overexpression of PagPXYa and PagPXYb in poplar did not have a significant impact on the growth status of transgenic plants under normal condition. However, when treated with 8 % PEG6000 or 100 mM H2O2, PagPXYa and PagPXYb overexpressing lines consistently exhibited more cambium cell layers, fewer xylem cell layers, and enhanced drought tolerance compared to the non-transgenic control '84K'. In addition, PagPXYs can alleviate the damage caused by H2O2 to the cambium under drought stress, thereby maintaining the cambial division activity of poplar under drought stress, indicating that PagPXYs play an important role in plant resistance to drought stress. This study provides a new insight for further research on the balance of growth and drought tolerance in forest trees.

Comparative analysis of PLATZ transcription factors in six poplar species and analysis of the role of PtrPLATZ14 in leaf development.

Plant AT-rich sequence and zinc-binding (PLATZ) proteins are a class of plant-specific transcription factor that play a crucial role in plant growth, development, and stress response. However, the evolutionary relationship of the PLATZ gene family across the Populus genus and the biological functions of the PLATZ protein require further investigation. In this study, we identified 133 PLATZ genes from six Populus species belonging to four Populus sections. Synteny analysis of the PLATZ gene family indicated that whole genome duplication events contributed to the expansion of the PLATZ family. Among the nine paralogous pairs, the protein structure of PtrPLATZ14/18 pair exhibited significant differences with others. Through gene expression patterns and co-expression networks, we discovered divergent expression patterns and sub-networks, and found that the members of pair PtrPLATZ14/18 might play different roles in the regulation of macromolecule biosynthesis and modification. Furthermore, we found that PtrPLATZ14 regulates poplar leaf development by affecting cell size control genes PtrGRF/GIF and PtrTCP. In conclusion, our study provides a theoretical foundation for exploring the evolution relationships and functions of the PLATZ gene family within Populus species and provides insights into the function and potential mechanism of PtrPLATZ14 in leaf morphology that were diverse across the Populus genus.

Magnetic resonance-guided focused ultrasound for essential tremor: a prospective, single center, single-arm study.

JOURNAL/nrgr/04.03/01300535-202409000-00041/figure1/v/2024-01-16T170235Z/r/image-tiff The safety and effectiveness of magnetic resonance-guided focused ultrasound thalamotomy has been broadly established and validated for the treatment of essential tremor. In 2018, the first magnetic resonance-guided focused ultrasound system in Chinese mainland was installed at the First Medical Center of the PLA General Hospital. This prospective, single center, open-label, single-arm study was part of a worldwide prospective multicenter clinical trial (ClinicalTrials.gov Identifier: NCT03253991) conducted to confirm the safety and efficacy of magnetic resonance-guided focused ultrasound for treating essential tremor in the local population. From 2019 to 2020, 10 patients with medication refractory essential tremor were recruited into this open-label, single arm study. The treatment efficacy was determined using the Clinical Rating Scale for Tremor. Safety was evaluated according to the incidence and severity of adverse events. All of the subjects underwent a unilateral thalamotomy targeting the ventral intermediate nucleus. At the baseline assessment, the estimated marginal mean of the Clinical Rating Scale for Tremor total score was 58.3 ± 3.6, and this improved after treatment to 23.1 ± 6.4 at a 12-month follow-up assessment. A total of 50 adverse events were recorded, and 2 were defined as serious. The most common intraoperative adverse events were nausea and headache. The most frequent postoperative adverse events were paresthesia and equilibrium disorder. Most of the adverse events were mild and usually disappeared within a few days. Our findings suggest that magnetic resonance-guided focused ultrasound for the treatment of essential tremor is effective, with a good safety profile, for patients in Chinese mainland.

Inequality Measure of Leaf Area Distribution for a Drought-Tolerant Landscape Plant.

Measuring the inequality of leaf area distribution per plant (ILAD) can provide a useful tool for quantifying the influences of intra- and interspecific competition, foraging behavior of herbivores, and environmental stress on plants' above-ground architectural structures and survival strategies. Despite its importance, there has been limited research on this issue. This paper aims to fill this gap by comparing four inequality indices to measure ILAD, using indices for quantifying household income that are commonly used in economics, including the Gini index (which is based on the Lorenz curve), the coefficient of variation, the Theil index, and the mean log deviation index. We measured the area of all leaves for 240 individual plants of the species Shibataea chinensis Nakai, a drought-tolerant landscape plant found in southern China. A three-parameter performance equation was fitted to observations of the cumulative proportion of leaf area vs. the cumulative proportion of leaves per plant to calculate the Gini index for each individual specimen of S. chinensis. The performance equation was demonstrated to be valid in describing the rotated and right shifted Lorenz curve, given that >96% of root-mean-square error values were smaller than 0.004 for 240 individual plants. By examining the correlation between any of the six possible pairs of indices among the Gini index, the coefficient of variation, the Theil index, and the mean log deviation index, the data show that these indices are closely related and can be used interchangeably to quantify ILAD.

CCNet: Criss-Cross Attention for Semantic Segmentation.

Contextual information is vital in visual understanding problems, such as semantic segmentation and object detection. We propose a criss-cross network (CCNet) for obtaining full-image contextual information in a very effective and efficient way. Concretely, for each pixel, a novel criss-cross attention module harvests the contextual information of all the pixels on its criss-cross path. By taking a further recurrent operation, each pixel can finally capture the full-image dependencies. Besides, a category consistent loss is proposed to enforce the criss-cross attention module to produce more discriminative features. Overall, CCNet is with the following merits: 1) GPU memory friendly. Compared with the non-local block, the proposed recurrent criss-cross attention module requires 11× less GPU memory usage. 2) High computational efficiency. The recurrent criss-cross attention significantly reduces FLOPs by about 85 percent of the non-local block. 3) The state-of-the-art performance. We conduct extensive experiments on semantic segmentation benchmarks including Cityscapes, ADE20K, human parsing benchmark LIP, instance segmentation benchmark COCO, video segmentation benchmark CamVid. In particular, our CCNet achieves the mIoU scores of 81.9, 45.76 and 55.47 percent on the Cityscapes test set, the ADE20K validation set and the LIP validation set respectively, which are the new state-of-the-art results. The source codes are available at https://github.com/speedinghzl/CCNethttps://github.com/speedinghzl/CCNet.

Peroxisome-Mediated Reactive Oxygen Species Signals Modulate Programmed Cell Death in Plants.

Peroxisomes are a class of simple organelles that play an important role in plant reactive oxygen species (ROS) metabolism. Experimental evidence reveals the involvement of ROS in programmed cell death (PCD) in plants. Plant PCD is crucial for the regulation of plant growth, development and environmental stress resistance. However, it is unclear whether the ROS originated from peroxisomes participated in cellular PCD. Enzymes involved in the peroxisomal ROS metabolic pathways are key mediators to figure out the relationship between peroxisome-derived ROS and PCD. Here, we summarize the peroxisomal ROS generation and scavenging pathways and explain how peroxisome-derived ROS participate in PCD based on recent progress in the functional study of enzymes related to peroxisomal ROS generation or scavenging. We aimed to elucidate the role of the peroxisomal ROS regulatory system in cellular PCD to show its potential in terms of accurate PCD regulation, which contribute to environmental stress resistance.

microRNAs: Key Players in Plant Response to Metal Toxicity.

Environmental metal pollution is a common problem threatening sustainable and safe crop production. Heavy metals (HMs) cause toxicity by targeting key molecules and life processes in plant cells. Plants counteract excess metals in the environment by enhancing defense responses, such as metal chelation, isolation to vacuoles, regulating metal intake through transporters, and strengthening antioxidant mechanisms. In recent years, microRNAs (miRNAs), as a small non-coding RNA, have become the central regulator of a variety of abiotic stresses, including HMs. With the introduction of the latest technologies such as next-generation sequencing (NGS), more and more miRNAs have been widely recognized in several plants due to their diverse roles. Metal-regulated miRNAs and their target genes are part of a complex regulatory network. Known miRNAs coordinate plant responses to metal stress through antioxidant functions, root growth, hormone signals, transcription factors (TF), and metal transporters. This article reviews the research progress of miRNAs in the stress response of plants to the accumulation of HMs, such as Cu, Cd, Hg, Cr, and Al, and the toxicity of heavy metal ions.

Integrating convolution and self-attention improves language model of human genome for interpreting non-coding regions at base-resolution.

Interpretation of non-coding genome remains an unsolved challenge in human genetics due to impracticality of exhaustively annotating biochemically active elements in all conditions. Deep learning based computational approaches emerge recently to help interpret non-coding regions. Here, we present LOGO (Language of Genome), a self-attention based contextualized pre-trained language model containing only two self-attention layers with 1 million parameters as a substantially light architecture that applies self-supervision techniques to learn bidirectional representations of the unlabelled human reference genome. LOGO is then fine-tuned for sequence labelling task, and further extended to variant prioritization task via a special input encoding scheme of alternative alleles followed by adding a convolutional module. Experiments show that LOGO achieves 15% absolute improvement for promoter identification and up to 4.5% absolute improvement for enhancer-promoter interaction prediction. LOGO exhibits state-of-the-art multi-task predictive power on thousands of chromatin features with only 3% parameterization benchmarking against the fully supervised model, DeepSEA and 1% parameterization against a recent BERT-based DNA language model. For allelic-effect prediction, locality introduced by one dimensional convolution shows improved sensitivity and specificity for prioritizing non-coding variants associated with human diseases. In addition, we apply LOGO to interpret type 2 diabetes (T2D) GWAS signals and infer underlying regulatory mechanisms. We make a conceptual analogy between natural language and human genome and demonstrate LOGO is an accurate, fast, scalable, and robust framework to interpret non-coding regions for global sequence labeling as well as for variant prioritization at base-resolution.

Treatment of Residual, Recurrent, or Metastatic Intracranial Hemangiopericytomas With Stereotactic Radiotherapy Using CyberKnife.

PURPOSE: Hemangiopericytomas are aggressive tumors known for their recurrence. The purpose of this study was to evaluate the management of residual, recurrent, and metastatic intracranial hemangiopericytomas using CyberKnife (CK) stereotactic radiotherapy (SRT). MATERIALS AND METHODS: Data were collected from 15 patients (28 tumors; eight men and seven women; 32-58 years) with residual, recurrent, or metastatic intracranial hemangiopericytomas, who were treated with stereotactic radiotherapy using CyberKnife between January 2014 and August 2019. All patients had previously been treated with surgical resection. Initial tumor volumes ranged from 0.84 to 67.2 cm3, with a mean volume of 13.06 cm3. The mean marginal and maximum radiosurgical doses to the tumors were 21.1 and 28.76 Gy, respectively. The mean follow-up time for tumors was 34.5 months, ranging from 13 to 77 months. RESULTS: 15 patients were alive after treatment; the mean post-diagnosis survival at censoring was 45.6 months (range 13-77 months). The volumes of the 28 tumors in the 15 followed patients were calculated after treatment. Postoperative magnetic resonance imaging revealed a mean tumor volume of 6.72 cm3 and a range of 0-67.2 cm3, with the volumes being significantly lower than pretreatment values. Follow-up imaging studies demonstrated tumor disappearance in seven (25%) of 28 tumors, reduction in 14 (50%), stability in one (3.57%), and recurrence in six (21.4%). Total tumor control was achieved in 22 (78.5%) of 28 tumors. The tumor grade and fraction time were not significantly associated with progression-free survival. Intracranial metastasis occurred in three patients, and extraneural metastasis in one patient. CONCLUSIONS: On the basis of the current results, stereotactic radiotherapy using CyberKnife is an effective and safe option for residual, recurrent, and metastatic intracranial hemangiopericytomas. Long-term close clinical and imaging follow-up is also necessary.

The Zap-X Radiosurgical System in the Treatment of Intracranial Tumors: A Technical Case Report.

BACKGROUND AND IMPORTANCE: The Zap-X system (Zap Surgical Systems Inc, San Carlos, California) is a radically new surgical robot designed for brain and head and neck radiosurgery. It represents the first new dedicated brain stereotactic radiosurgery platform in almost half a century optimizing the goals of safety, speed, and accuracy. The Zap-X system was used in a required Chinese National Medical Products Administration clinical study. In early January 2020, 2 patients were treated with the Zap-X robot prior to a national COVID-19 lockdown. Both were closely followed via clinical exam and magnetic resonance imaging (MRI) imaging. Prospectively collected data were used to generate this report. CLINICAL PRESENTATION: Two female patients, each harboring either a trigeminal schwannoma or petroclival meningioma, were treated with the Zap-X robot. Respective tumor volumes were 2.60 and 4.02 cm3. A radiation dose of 13 Gy was prescribed to the 50% isodose line. At 8 mo of follow-up, preoperative symptoms were either resolved or stable and MRI imaging demonstrated a 31% and 56% reduction in lesion volume, respectively. In both patients, symptoms improved, and tumor volumes decreased, whereas no major complication was observed. CONCLUSION: Given only 2 patients and short-term follow-up, any conclusions about the safety and efficacy of the Zap-X radiosurgery robot are preliminary. However, in the absence of any other published outcomes to date, this small case series may be of interest to many radiosurgical specialists.

Transcriptional programs of infectious spleen and kidney necrosis virus (ISKNV) in vitro and in vivo.

Infectious spleen and kidney necrosis virus (ISKNV), causing serious infectious diseases to marine and freshwater fishes, is the type species of the genus Megalocytivirus, family Iridoviridae. In this study, the transcriptional programs of ISKNV in vitro (MFF-1 cells) and in vivo (spleens from mandarin fish) were investigated using real-time PCR. Transcription of all the putative open reading frames (ORFs) of ISKNV was verified. The temporal expression patterns of ISKNV ORFs in vitro and in vivo, including peak expression times (PETs) and relative maximal expression levels, were determined and compared. The K-means clustering with Spearman rank correlation was generated in heat maps constructed based on ISKNV ORF expression profiles in vivo and in vitro. The current study may provide a global picture of ISKNV infection at the transcription level and help better understand the molecular pathogenic mechanism of megalocytiviruses.

A novel SOS1-ALK fusion variant in a patient with metastatic lung adenocarcinoma and a remarkable response to crizotinib.

OBJECTIVES: Transforming anaplastic lymphoma kinase (ALK) gene rearrangements are well known as a unique subset of non-small cell lung cancer (NSCLC) with mutations other than EGFR. Currently, crizotinib is the standard first-line treatment for ALK-positive NSCLC. MATERIALS AND METHODS: With advances in detection methods, more and more uncommon ALK fusion partners have been identified. Herein we present a novel SOS1-ALK fusion and the efficacy of crizotinib in an advanced NSCLC patient harboring this type of fusion. RESULTS: A 52-year-old Chinese man had left upper lobe primary NSCLC and synchronous multiple lung metastases (cT2N3M1, stage IV). The ultrasound-guided fine-needle aspiration cytology of palpable left supraclavicular lymph nodes and the results of immunohistochemistry staining supported the diagnosis of metastatic lung adenocarcinoma. Using a next-generation sequencing assay (NGS), we showed that the tumor had a SOS1-ALK fusion which the breakpoints was (S2, A20) rather than other actionable mutations. Therefore, the patient received first-line crizotinib and experienced a remarkable tumor response and has tolerated crizotinib well until this writing. CONCLUSION: Considering this rare SOS1-ALK fusion and remarkable response to an ALK-inhibitor, it is important to be aware of the presence of SOS1-ALK fusions in patients with advanced NSCLC to better guide targeted therapy. Precision methods, such as NGS for oncogenic alteration detection, should also be encouraged in clinical practice.

Using Heading date 1 preponderant alleles from indica cultivars to breed high-yield, high-quality japonica rice varieties for cultivation in south China.

Heading date 1 (Hd1) is an important gene for the regulation of flowering in rice, but its variation in major cultivated rice varieties, and the effect of this variation on yield and quality, remains unknown. In this study, we selected 123 major rice varieties cultivated in China from 1936 to 2009 to analyse the relationship between the Hd1 alleles and yield-related traits. Among these varieties, 19 haplotypes were detected in Hd1, including two major haplotypes (H8 and H13) in the japonica group and three major haplotypes (H14, H15 and H16) in the indica group. Analysis of allele frequencies showed that the secondary branch number was the major aimed for Chinese indica breeding. In the five major haplotypes, SNP316 (C-T) was the only difference between the two major japonica haplotypes, and SNP495 (C-G) and SNP614 (G-A) are the major SNPs in the three indica haplotypes. Association analysis showed that H16 is the most preponderant allele in modern cultivated Chinese indica varieties. Backcrossing this allele into the japonica variety Chunjiang06 improved yield without decreasing grain quality. Therefore, our analysis offers a new strategy for utilizing these preponderant alleles to improve yield and quality of japonica varieties for cultivation in the southern areas of China.

Therapeutic Effect of Hypofractionated Stereotactic Radiotherapy Using CyberKnife for High Volume Cavernous Sinus Cavernous Hemangiomas.

OBJECTIVE: To evaluate the efficacy and safety of hypofractionated stereotactic radiotherapy using CyberKnife for high volume cavernous sinus cavernous hemangiomas. MATERIALS AND METHODS: We collected data from 12 patients with high volume cavernous sinus cavernous hemangiomas treated with hypofractionated stereotactic radiotherapy using CyberKnife in our institute, including 2 men and 10 women/female child, aged 4 to 60 years. Initial tumor volumes ranged from 11.8 to 96.6 cm3 with a median of 24.3 cm3. Irradiation doses were 19.5 Gy with 3 fractions in 2 patients, 21 Gy with 3 fractions in 8 patients, 25 Gy with 5 fractions in 1 patient, and 30 Gy with 3 fractions in 1 patient. We used 109 to 155 beams during treatment, and target volumes reached over 95% of the prescribed dose. Follow-up ranged from 3 to 54 months. We evaluated the efficacy and safety of the CyberKnife system based on changes in the diagnostic images and involved cranial nerves or symptoms. RESULTS: Of the 12 patients, 11 were followed for 3 to 54 months with a mean follow-up of 16.3 months; 1 patient was lost to in-person follow-up. Lesion volumes in the followed 11 patients were calculated after fractionated radiotherapy. All tumor volumes decreased (28.6%-94.1%) and symptoms improved (including blurred vision, visual field defects, diplopia, headaches, and facial numbness) after therapy. Postoperative magnetic resonance images revealed a tumor volume range of 2.8 to 41.0 cm3 (median, 6.5 cm3), significantly lower compared with the pretreatment range of 11.8 to 70.1 cm3 (median, 24.3 cm3; T = 0.00, P = .003 < .05). A single patient experienced radiotherapy-related cerebral edema, which resolved after 5 days of mannitol and dexamethasone. CONCLUSIONS: Based on the current results, though preliminary, hypofractionated stereotactic radiotherapy using CyberKnife is an effective and safe alternative for high volume cavernous sinus cavernous hemangiomas and is the recommended primary treatment in high-risk patients with this condition.

A Nck-associated protein 1-like protein affects drought sensitivity by its involvement in leaf epidermal development and stomatal closure in rice.

Water deficit is a major environmental threat affecting crop yields worldwide. In this study, a drought stress-sensitive mutant drought sensitive 8 (ds8) was identified in rice (Oryza sativa L.). The DS8 gene was cloned using a map-based approach. Further analysis revealed that DS8 encoded a Nck-associated protein 1 (NAP1)-like protein, a component of the SCAR/WAVE complex, which played a vital role in actin filament nucleation activity. The mutant exhibited changes in leaf cuticle development. Functional analysis revealed that the mutation of DS8 increased stomatal density and impaired stomatal closure activity. The distorted actin filaments in the mutant led to a defect in abscisic acid (ABA)-mediated stomatal closure and increased ABA accumulation. All these resulted in excessive water loss in ds8 leaves. Notably, antisense transgenic lines also exhibited increased drought sensitivity, along with impaired stomatal closure and elevated ABA levels. These findings suggest that DS8 affects drought sensitivity by influencing actin filament activity.

PALE-GREEN LEAF12 Encodes a Novel Pentatricopeptide Repeat Protein Required for Chloroplast Development and 16S rRNA Processing in Rice.

Pentatricopeptide repeat (PPR) proteins regulate organellar gene expression in plants, through their involvement in organellar RNA metabolism. In rice (Oryza sativa), 477 genes are predicted to encode PPR proteins; however, the majority of their functions remain unknown. In this study, we identified and characterized a rice mutant, pale-green leaf12 (pgl12); at the seedling stage, pgl12 mutants had yellow-green leaves, which gradually turned pale green as the plants grew. The pgl12 mutant had significantly reduced Chl contents and increased sensitivity to changes in temperature. A genetic analysis revealed that the pgl12 mutation is recessive and located within a single nuclear gene. Map-based cloning of PGL12, including a transgenic complementation test, confirmed the presence of a base substitution (C to T), generating a stop codon, within LOC_Os12g10184 in the pgl12 mutant. LOC_Os12g10184 encodes a novel PLS-type PPR protein containing 17 PPR motifs and targeted to the chloroplasts. A quantitative real-time PCR analysis showed that PGL12 was expressed in various tissues, especially the leaves. We also showed that the transcript levels of several nuclear- and plastid-encoded genes associated with chloroplast development and photosynthesis were significantly altered in pgl12 mutants. The mutant exhibited defects in the 16S rRNA processing and splicing of the plastid transcript ndhA. Our results indicate that PGL12 is a new PLS-type PPR protein required for proper chloroplast development and 16S rRNA processing in rice.

Imaging of Sodium MRI for Therapy Evaluation of Brain Metastase with Cyberknife at 7T: A Case Report.

Herein we describe the case of an elderly patient who presented with a recent history of impaired vision of the right eye around three months due to brain lesions. He was diagnosed with liver cancer and underwent surgery three months prior. The pathological result is hepatocellular carcinoma. Magnetic resonance imaging (MRI) revealed the diagnosis of brain to be metastatic. The patient selected CyberKnife (Accuray Incorporated, Sunnyvale, USA) radiosurgery for the brain lesion since his physical conditions are not suitable for craniotomy. We adapt the imaging of sodium MRI and proton diffusion mapping at 7T MR system to evaluate the efficacy following CyberKnife early stage treatment. To date, we find the tissue sodium concentration (TSC) changes with the time whereas the proton MRI has no significant change within one month. The time course of sodium concentration in the tumor showed a dramatic increase in the treated brain tumor compared to the pretreatment sodium concentration and 48 hours after stereotactic radiosurgery (SRS), which is correlated to the period of the radiotherapy-induced cellular necrosis. This case demonstrates the possibility of sodium MRI as a biomarker for monitoring early radiotherapy for assessing tumor cellularity.

A Rice PECTATE LYASE-LIKE Gene Is Required for Plant Growth and Leaf Senescence.

To better understand the molecular mechanisms behind plant growth and leaf senescence in monocot plants, we identified a mutant exhibiting dwarfism and an early-senescence leaf phenotype, termed dwarf and early-senescence leaf1 (del1). Histological analysis showed that the abnormal growth was caused by a reduction in cell number. Further investigation revealed that the decline in cell number in del1 was affected by the cell cycle. Physiological analysis, transmission electron microscopy, and TUNEL assays showed that leaf senescence was triggered by the accumulation of reactive oxygen species. The DEL1 gene was cloned using a map-based approach. It was shown to encode a pectate lyase (PEL) precursor that contains a PelC domain. DEL1 contains all the conserved residues of PEL and has strong similarity with plant PelC. DEL1 is expressed in all tissues but predominantly in elongating tissues. Functional analysis revealed that mutation of DEL1 decreased the total PEL enzymatic activity, increased the degree of methylesterified homogalacturonan, and altered the cell wall composition and structure. In addition, transcriptome assay revealed that a set of cell wall function- and senescence-related gene expression was altered in del1 plants. Our research indicates that DEL1 is involved in both the maintenance of normal cell division and the induction of leaf senescence. These findings reveal a new molecular mechanism for plant growth and leaf senescence mediated by PECTATE LYASE-LIKE genes.

Rational design of high-yield and superior-quality rice.

Rice (Oryza sativa L.) is a staple food for more than half of the world's population. To meet the ever-increasing demand for food, because of population growth and improved living standards, world rice production needs to double by 20301. The development of new elite rice varieties with high yield and superior quality is challenging for traditional breeding approaches, and new strategies need to be developed. Here, we report the successful development of new elite varieties by pyramiding major genes that significantly contribute to grain quality and yield from three parents over five years. The new varieties exhibit higher yield potential and better grain quality than their parental varieties and the China's leading super-hybrid rice, Liang-you-pai-jiu (LYP9 or Pei-ai 64S/93-11). Our results demonstrate that rational design is a powerful strategy for meeting the challenges of future crop breeding, particularly in pyramiding multiple complex traits.