NUCLEAR TRANSPORT FACTOR 2-LIKE improves drought tolerance by modulating leaf water loss in alfalfa (Medicago sativa L.).

Drought is a major environmental factor that limits the production of alfalfa (Medicago sativa). In the present study, M. sativa NUCLEAR TRANSPORT FACTOR 2-LIKE (MsNTF2L) was identified as a nucleus-, cytoplasm-, and plasma membrane-localized protein. Its transcriptional expression was highly induced by ABA and drought stress. Overexpression of MsNTF2L in Arabidopsis resulted in hypersensitivity to ABA during both the seed germination and seedling growth stages. However, transgenic Arabidopsis plants exhibited enhanced tolerance to drought stress by reducing the levels of reactive oxygen species (ROS) and increasing the expression of stress/ABA-inducible genes. Consistently, analysis of MsNTF2L overexpression (OE) and RNA interference (RNAi) alfalfa plants revealed that MsNTF2L confers drought tolerance through promoting ROS scavenging, a decrease in stomatal density, ABA-induced stomatal closure, and epicuticular wax crystal accumulation. MsNTF2L highly affected epicuticular wax deposition, as a large group of wax biosynthesis and transport genes were influenced in the alfalfa OE and RNAi lines. Furthermore, transcript profiling of drought-treated alfalfa WT, OE, and RNAi plants showed a differential drought response for genes related to stress/ABA signaling, antioxidant defense, and photosynthesis. Taken together, these results reveal that MsNTF2L confers drought tolerance in alfalfa via modulation of leaf water loss (by regulating both stomata and wax deposition), antioxidant defense, and photosynthesis.

Bidirectional lncRNA Transfer between Cuscuta Parasites and Their Host Plant.

Dodder species (Cuscuta spp.) are holoparasites that have extensive material exchange with their host plants through vascular connections. Recent studies on cross-species transfer have provided breakthrough insights, but little is known about the interaction mechanisms of the inter-plant mobile substances in parasitic systems. We sequenced the transcriptomes of dodder growing on soybean hosts to characterize the long non-coding RNA (lncRNA) transfer between the two species, and found that lncRNAs can move in high numbers (365 dodder lncRNAs and 14 soybean lncRNAs) in a bidirectional manner. Reverse transcription-polymerase chain reaction further confirmed that individual lncRNAs were trafficked in the dodder-soybean parasitic system. To reveal the potential functions of mobile transcripts, the Gene Ontology terms of mobile lncRNA target genes were predicted, and mobile dodder target genes were found to be mainly enriched in "metabolic process", "catalytic activity", "signaling", and "response to stimulus" categories, whereas mobile soybean target genes were enriched in organelle-related categories, indicating that specific mobile lncRNAs may be important in regulating dodder parasitism. Our findings reveal that lncRNAs are transferred between dodder and its host soybean plants, which may act as critical regulators to coordinate the host-dodder interaction at the whole parasitic level.

Full-length transcript sequencing and comparative transcriptomic analysis to evaluate the contribution of osmotic and ionic stress components towards salinity tolerance in the roots of cultivated alfalfa (Medicago sativa L.).

BACKGROUND: Alfalfa is the most extensively cultivated forage legume. Salinity is a major environmental factor that impacts on alfalfa's productivity. However, little is known about the molecular mechanisms underlying alfalfa responses to salinity, especially the relative contribution of the two important components of osmotic and ionic stress. RESULTS: In this study, we constructed the first full-length transcriptome database for alfalfa root tips under continuous NaCl and mannitol treatments for 1, 3, 6, 12, and 24 h (three biological replicates for each time points, including the control group) via PacBio Iso-Seq. This resulted in the identification of 52,787 full-length transcripts, with an average length of 2551 bp. Global transcriptional changes in the same 33 stressed samples were then analyzed via BGISEQ-500 RNA-Seq. Totals of 8861 NaCl-regulated and 8016 mannitol-regulated differentially expressed genes (DEGs) were identified. Metabolic analyses revealed that these DEGs overlapped or diverged in the cascades of molecular networks involved in signal perception, signal transduction, transcriptional regulation, and antioxidative defense. Notably, several well characterized signalling pathways, such as CDPK, MAPK, CIPK, and PYL-PP2C-SnRK2, were shown to be involved in osmotic stress, while the SOS core pathway was activated by ionic stress. Moreover, the physiological shifts of catalase and peroxidase activity, glutathione and proline content were in accordance with dynamic transcript profiles of the relevant genes, indicating that antioxidative defense system plays critical roles in response to salinity stress. CONCLUSIONS: Overall, our study provides evidence that the response to salinity stress in alfalfa includes both osmotic and ionic components. The key osmotic and ionic stress-related genes are candidates for future studies as potential targets to improve resistance to salinity stress via genetic engineering.

Comparative Transcriptomic and Physiological Analyses of Medicago sativa L. Indicates that Multiple Regulatory Networks Are Activated during Continuous ABA Treatment.

Alfalfa is the most extensively cultivated forage legume worldwide. However, the molecular mechanisms underlying alfalfa responses to exogenous abscisic acid (ABA) are still unknown. In this study, the first global transcriptome profiles of alfalfa roots under ABA treatments for 1, 3 and 12 h (three biological replicates for each time point, including the control group) were constructed using a BGISEQ-500 sequencing platform. A total of 50,742 isoforms with a mean length of 2541 bp were generated, and 4944 differentially expressed isoforms (DEIs) were identified after ABA deposition. Metabolic analyses revealed that these DEIs were involved in plant hormone signal transduction, transcriptional regulation, antioxidative defense and pathogen immunity. Notably, several well characterized hormone signaling pathways, for example, the core ABA signaling pathway, was activated, while salicylic acid, jasmonate and ethylene signaling pathways were mainly suppressed by exogenous ABA. Moreover, the physiological work showed that catalase and peroxidase activity and glutathione and proline content were increased after ABA deposition, which is in accordance with the dynamic transcript profiles of the relevant genes in antioxidative defense system. These results indicate that ABA has the potential to improve abiotic stress tolerance, but that it may negatively regulate pathogen resistance in alfalfa.

Multiple Regulatory Networks Are Activated during Cold Stress in Medicago sativa L.

Cultivated alfalfa (Medicago sativa L.) is one of the most important perennial legume forages in the world, and it has considerable potential as a valuable forage crop for livestock. However, the molecular mechanisms underlying alfalfa responses to cold stress are largely unknown. In this study, the transcriptome changes in alfalfa under cold stress at 4 °C for 2, 6, 24, and 48 h (three replicates for each time point) were analyzed using the high-throughput sequencing platform, BGISEQ-500, resulting in the identification of 50,809 annotated unigenes and 5283 differentially expressed genes (DEGs). Metabolic pathway enrichment analysis demonstrated that the DEGs were involved in carbohydrate metabolism, photosynthesis, plant hormone signal transduction, and the biosynthesis of amino acids. Moreover, the physiological changes of glutathione and proline content, catalase, and peroxidase activity were in accordance with dynamic transcript profiles of the relevant genes. Additionally, some transcription factors might play important roles in the alfalfa response to cold stress, as determined by the expression pattern of the related genes during 48 h of cold stress treatment. These findings provide valuable information for identifying and characterizing important components in the cold signaling network in alfalfa and enhancing the understanding of the molecular mechanisms underlying alfalfa responses to cold stress.

Novel preparation of Au nanoparticles loaded Laponite nanoparticles/ECM injectable hydrogel on cardiac differentiation of resident cardiac stem cells to cardiomyocytes.

Cardiac tissue engineering offers a facile biomedical technology to develop a cardiac tissue regeneration or tissue repair by involving combinations of effective biomaterials and nanomaterials with engineering strategies. The cardiac regenerative materials were fabricated by electrically active nanoparticles onto the biocompatible matrix to inspire low-resistance electrical signal in the native heart tissues. In the current report, we investigated on the improvement of cardiac functionally inspired conductive injectable hydrogel fabricated from the electroactive gold (Au) and laponite (Lap) nanoparticles loaded myocardial extracellular matrix (ECM) to enhance the functional and biological properties of cardiomyocytes. The incorporation of nanoformulations into the ECM was maintained the functionality behaviors and maintenance of electrical conductivity into cardiomyocytes. The effects of nanoparticles onto the ECM were provided decreasing porous structure and interconnected pores in the hydrogel structure for the favorable environment of cardiac tissues. The biological analysis of cell survival and immunostaining studies of cardiomyocytes established that Au loaded Lap/ECM hydrogel improve cell compatibility and phenotypes maturation of cardiac specific proteins. The combination of electrically active nanoformulations and biologically active ECM was enhanced the cell expression of cardiac specific markers (SAC, cTnl and Cx43), indicating the potential role of nanoparticles loaded ECM hydrogel as an appropriate cardiac regenerative material for the repair of infarcted myocardium.

[Freeze resistance analysis of different wheat cultivars based on the relationships between physiological indices and grain yield].

A pot experiment with twenty wheat cultivars was conducted to investigate the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities and the MDA, soluble protein and soluble sugar contents of functional leaves as well as the grain yield, 1000-grain weight, and grain morphological characters under low temperature stress. Low temperature (-4 degrees C) stress at stem elongation stage resulted in the changes of grain morphology and yield characters. For most of test cultivars, their grain length-width ratio, grain roundness, and sterile spikelets increased, and their grain equivalent diameter, grain area, 1000-grain weight, and grain yield decreased. Path analysis indicated that after treated with low temperature at stem elongation stage, the SOD activity and soluble sugar content of functional leaves, especially the SOD activity (direct path coefficient -0. 578) , were the dominant factors affecting grain yield. Taking the percentage of decreased grain yield due to low temperature stress as the assessment criterion, the test twenty winter wheat cultivars were divided into three groups. Cultivars Jimai 19, Jimai 20, Liangxing 99, Shannong 1135, Shannong 8355, Taishan 23, Taishan 9818, Wennong 6, and Yannong 21 belonged to high freeze resistance group, cultivars Linmai 2, Weimai 8, Yannong 19, and Zimai 12 were of low freeze resistance group, and the other seven cultivars belonged to medium freeze resistance group. The seedling stage comprehensive assessment index (D value) had a significant negative correlation with the percentage of decreased grain yield (r = -0. 512*), suggesting that the stronger freeze resistance of wheat at seedling stage was beneficial to the higher wheat grain yield, and seedling stage was the critical period to be selected to identify the freeze resistance of wheat.