Lower Water Loss Rates Research Articles

The transcription factor TabZIP156 acts as a positive regulator in response to drought tolerance in Arabidopsis and wheat (Triticum aestivum L.)

Drought stress strongly restricts the growth, development, and yield of wheat worldwide. Among the various transcription factors (TFs) involved in the wheat drought response, the specific functions of many basic leucine zipper (bZIP) TFs related to drought tolerance are still not well understood. In this study, we focused on the bZIP TF TabZIP156 in wheat. Our analysis showed that TabZIP156 was highly expressed in both roots and leaves, and it responded to drought and abscisic acid (ABA) stress. Through subcellular localization and transactivation assays, we confirmed that TabZIP156 was located to the nucleus and functioned as a transcriptional activator. Overexpression of TabZIP156 in Arabidopsis enhanced drought tolerance, as evidenced by higher germination rate, longer root length, lower water loss rate, reduced ion leakage, increased proline accumulation, decreased levels of H2O2, O2− and MDA, and improved activities of POD, SOD, and CAT enzymes. Additionally, the expression of drought- and antioxidant-related genes were significantly upregulated in TabZIP156 transgenic Arabidopsis under drought stress. However, silencing TabZIP156 in wheat led to decreased proline content, increased accumulation of H2O2, O2− and MDA, reduced activities of antioxidant enzymes, and downregulation of many drought- and antioxidant-related genes under drought stress. Furthermore, the dual-luciferase assay demonstrated that TabZIP156 could activate the expression of TaP5CS, TaDREB1A, and TaPOD by binding to their promoters. Taken together, this study highlights the significant role of TabZIP156 in drought stress and provides valuable insights for its potential application in breeding drought-resistant wheat.

Overexpression of SlALC Increases Drought and Salt Tolerance and Affects Fruit Dehiscence in Tomatoes.

The bHLH transcription factors are important plant regulators against abiotic stress and involved in plant growth and development. In this study, SlALC, a gene coding for a prototypical DNA-binding protein in the bHLH family, was isolated, and SlALC-overexpression tomato (SlALC-OE) plants were generated by Agrobacterium-mediated genetic transformation. SlALC transgenic lines manifested higher osmotic stress tolerance than the wild-type plants, estimated by higher relative water content and lower water loss rate, higher chlorophyll, reducing sugar, starch, proline, soluble protein contents, antioxidant enzyme activities, and lower MDA and reactive oxygen species contents in the leaves. In SlALC-OE lines, there were more significant alterations in the expression of genes associated with stress. Furthermore, SlALC-OE fruits were more vulnerable to dehiscence, with higher water content, reduced lignin content, SOD/POD/PAL enzyme activity, and lower phenolic compound concentrations, all of which corresponded to decreased expression of lignin biosynthetic genes. Moreover, the dual luciferase reporter test revealed that SlTAGL1 inhibits SlALC expression. This study revealed that SlALC may play a role in controlling plant tolerance to drought and salt stress, as well as fruit lignification, which influences fruit dehiscence. The findings of this study have established a foundation for tomato tolerance breeding and fruit quality improvement.

The U1 small nuclear RNA enhances drought tolerance in Arabidopsis.

Alternative splicing (AS) is an important post-transcriptional regulatory mechanism that improves plant tolerance to drought stress by modulating gene expression and generating proteome diversity. The interaction between the 5' end of U1 small nuclear RNA (U1 snRNA) and the conserved 5' splice site of precursor messenger RNA (pre-mRNA) is pivotal for U1 snRNP involvement in AS. However, the roles of U1 snRNA in drought stress responses remain unclear. This study provides a comprehensive analysis of AtU1 snRNA in Arabidopsis (Arabidopsis thaliana), revealing its high conservation at the 5' end and a distinctive four-leaf clover structure. AtU1 snRNA is localized in the nucleus and expressed in various tissues, with prominent expression in young floral buds, flowers, and siliques. Overexpression of AtU1 snRNA confers enhanced abiotic stress tolerance, as evidenced in seedlings by longer seedling primary root length, increased fresh weight, and a higher greening rate compared to the wild type. Mature AtU1 snRNA overexpressor plants exhibit higher survival rates and lower water loss rates under drought stress, accompanied by a significant decrease in H2O2 and increase in proline. This study also provides evidence of altered expression levels of drought-related genes in AtU1 snRNA overexpressor or genome-edited lines, reinforcing the crucial role of AtU1 snRNA in drought stress responses. Furthermore, the overexpression of AtU1 snRNA influences the splicing of downstream target genes, with a notable impact on SPEECHLESS (SPCH), a gene associated with stomatal development, potentially explaining the observed decrease in stomatal aperture and density. These findings elucidate the critical role of U1 snRNA as an AS regulator in enhancing drought stress tolerance in plants, contributing to a deeper understanding of the AS pathway in drought tolerance and increasing awareness of the molecular network governing drought tolerance in plants.

Maize auxin response factor ZmARF1 confers multiple abiotic stresses resistances in transgenic Arabidopsis.

Prolonged exposure to abiotic stresses causes oxidative stress, which affects plant development and survival. In this research, the overexpression of ZmARF1 improved tolerance to low Pi, drought and salinity stresses. The transgenic plants manifested tolerance to low Pi by their superior root phenotypic traits: root length, root tips, root surface area, and root volume, compared to wide-type (WT) plants. Moreover, the transgenic plants exhibited higher root and leaf Pi content and upregulated the high affinity Pi transporters PHT1;2 and phosphorus starvation inducing (PSI) genes PHO2 and PHR1 under low Pi conditions. Transgenic Arabidopsis displayed tolerance to drought and salt stress by maintaining higher chlorophyll content and chlorophyll fluorescence, lower water loss rates, and ion leakage, which contributed to the survival of overexpression lines compared to the WT. Transcriptome profiling identified a peroxidase gene, POX, whose transcript was upregulated by these abiotic stresses. Furthermore, we confirmed that ZmARF1 bound to the auxin response element (AuxRE) in the promoter of POX and enhanced its transcription to mediate tolerance to oxidative stress imposed by low Pi, drought and salt stress in the transgenic seedlings. These results demonstrate that ZmARF1 has significant potential for improving the tolerance of crops to multiple abiotic stresses.

Accelerated self-assembly of filipin proteins and formation of hydrogels

This study delineates the novel revelation that traditional Chinese medicine polysaccharides facilitate and expedite the intramolecular conformational alterations within filipin proteins, culminating in amplified β-fold content and self-assembly proclivity to generate hydrogels. Augmentation of assembly kinetics was achieved by pH or ethanol supplementation. The resultant self-assembled hydrogels exhibited homogenous pore size distribution, registering porosities consistently surpassing 95 ± 2.3%, effectively accommodating pharmaceutical payloads. Noteworthy characteristics included low water loss rates spanning between 15% and 25%, exceptional swelling behavior, a storage modulus (G') ranging from 68 to 283 Pa, and discernible mechanical robustness. Insights into the self-assembly mechanism were preliminarily explained via Fourier infrared, Raman spectroscopy and X-ray diffraction spectroscopy analyses. In-depth examinations, encompassing in-vitro release, degradation and biocompatibility, corroborated the hydrogel’s capacity for smooth drug release, sustained stability, absence of cytotoxicity and favorable biocompatibility. In conclusion, the self-assembled filipin protein hydrogels preserved polysaccharide activity to a heightened extent and enhanced drug adaptability by reducing the overall formulation volume. This innovation, we suggest, holds significant promise for applications in sustained drug release and in the realm of tissue engineering materials.

Effects of fermented herbal tea residue on meat quality, rumen fermentation parameters and microbes of black goats

Herbal tea residue (HTR) is generally considered to be a reusable resource which has still retains considerable proportion of nutrients and active substances. This study aimed to investigate the effects of substitution of whole corn silage with fermented herbal tea residue (FHTR) on meat quality, serum indices, rumen fermentation, and microbes in Chuanzhong black goats. Twenty-two female Chuanzhong black goats (4 months old) with similar weight (9.55 ± 0.95 kg) were selected and randomly divided into two groups. FHTR was used to replace 0% (CON group) and 30% (FHTR group) of whole corn silage in the diets and fed as a total mixed ration (TMR) for Chuanzhong black goats. The adaptation feeding period was 7 days, and the experimental period was 35 days. Results illustrated that the FHTR group had higher value of a* and concentrations of DM and CP and lower rate of water loss (P < 0.05) than the CON group. For the serum indices, goats fed with 30% FHTR had higher (P < 0.05) concentration of CR on day 35. For rumen fermentation, the pH and ratio of acetic acid/propionic acid (AA/PA) in the FHTR group were significantly lower than those in the CON group (P < 0.05). In addition, we studied the goats’s rumen microbial community composition and found that the dominant phyla were Firmicutes, Bacteroidetes,and Tenericutes; and the dominant genera were Quinella, Candidatus_Saccharimonas, and Saccharofermentans. There was a significant difference in the beta diversity of the rumen microbiota between groups (P < 0.05). To sum up, the addition of FHTR can affect the meat quality, serum indices, improved rumen fermentation by adjusted the diversity and function of the rumen microbiota.

Year-round growth potential and moisture stress tolerance of buckwheat (Fagopyrum esculentum L.) under fragile hill ecosystems of the Eastern Himalayas (India)

IntroductionUnder a changing climate, the fragile ecosystems of the Eastern Himalayas (EH) are persistently challenged by prolonged dry spells and erratic rainfall. Identification of suitable high-yielding crops with higher moisture stress tolerance and adaptability is paramount for the region. Although the region received a good amount of rainfall in the rainy season, the winter months, viz., November to March, rarely received any rain. Even within the rainy season, there are several intermittent drought spells that hinder crop productivity.MethodsThe present study has used field and microcosm experiments to assess the year-round cultivation potential and extent of moisture stress tolerance in the lesser-known buckwheat crop of the region.Results and discussionSowing of buckwheat from mid-September to mid-December produced better grain yield, the highest being when sowing in October (9.83 q ha−1) and the crop was found suitable to grow all through the year for higher green biomass (12.6–38.4 q ha−1). The moisture stress tolerance of buckwheat was significantly enhanced by increased total root length and root surface area by 12.4 and 34.7%, respectively. Increased photo-protective carotenoids, chlorophyll b, and favorable stomatal attributes with substantial epicuticular wax have significantly improved the moisture stress tolerance of Buckwheat. In addition, leaf proline was found 25.4% higher and total soluble protein, reducing sugar, and cell membrane stability were found 29.2, 38.1, and 36.5% lower compared to the control, respectively. A significantly lower rate of water loss (25.6%) with its stomatal and non-stomatal adaptations and versatile pollen structural traits under moisture stress over control, make the buckwheat crop potentially more stress tolerant and economical crop for EH of India.

Overexpression of a WRKY transcription factor McWRKY57-like from Mentha canadensis L. enhances drought tolerance in transgenic Arabidopsis

BackgroundDrought has become a major environmental problem affecting crop production. Members of the WRKY family play important roles in plant development and stress responses. However, their roles in mint have been barely explored.ResultsIn this study, we isolated a drought-inducible gene McWRKY57-like from mint and investigated its function. The gene encodes a group IIc WRKY transcription factor, McWRKY57-like, which is a nuclear protein with a highly conserved WRKY domain and a C2H2 zinc-finger structure, and has transcription factor activity. Its expression levels were examined in different tissues of mint and under the treatment of mannitol, NaCl, abscisic acid, and methyl jasmonate. We found that McWRKY57-like overexpression in Arabidopsis significantly increased drought tolerance. Further studies showed that under drought stress, McWRKY57-like-overexpressing plants had higher chlorophyll, soluble sugar, soluble protein, and proline contents but lower water loss rate and malondialdehyde content than wild-type plants. Moreover, the activities of antioxidant enzymes catalase, superoxide dismutase, and peroxidase were enhanced in McWRKY57-like transgenic plants. Furthermore, qRT-PCR analysis revealed that the drought-related genes AtRD29A, AtRD29B, AtRD20, AtRAB18, AtCOR15A, AtCOR15B, AtKIN2, and AtDREB1A were upregulated in McWRKY57-like transgenic plants than in wild-type Arabidopsis under simulated drought conditions.ConclusionThese data demonstrated that McWRKY57-like conferred drought tolerance in transgenic Arabidopsis by regulating plant growth, osmolyte accumulation and antioxidant enzyme activities, and the expression of stress-related genes. The study indicates that McWRKY57-like plays a positive role in drought response in plants.

Evaluation of Meat Quality of Local Pigeon Varieties in China.

To evaluate the germplasm characteristics and nutritional value of Chinese native pigeon varieties, this study analyzed the nutrient composition of the meat of four Chinese native pigeon varieties and then compared them with those of the White King pigeon, which is the most commonly used in China. A total of 150 pigeons aged 28 d (squabs) of 5 breeds including Taihu pigeon, Shiqi pigeon, Ta-rim pigeon, Boot pigeon, and White King pigeon were selected for slaughter. The basic meat quality parameters and contents of conventional nutritional compositions, inosine acid, amino acids, and fatty acids were measured. The results showed that there were significant differences in flesh color (L*, b*), pH, and water loss rate of different breeds of suckling pigeons (p < 0.05). Compared with White King pigeons, four local breeds had dark breast meat and a low water loss rate. The protein contents of Taihu, Tarim, and Shiqi suckling pigeons were significantly higher than those of White King pigeons (p < 0.05). Taihu pigeons had the highest protein content, reaching 22.72%. The inosinic acid content of Tarim pigeons was the highest (1.31 mg/g) and was significantly higher than that of Shiqi pigeons, Boot pigeons, and White King pigeons (p < 0.05). There was no significant difference in the content of amino acids, the ratio of essential amino acids, and the ratio of umami amino acids in the meat of different breeds of pigeons (p > 0.05). The percentage of saturated fatty acids (SFAs) in the breast muscle of local breeding pigeons was significantly lower than that of White King pigeons (p < 0.05), and the percentages of lauric acid, palmitic acid, eicosanoic acid, and behenic acid in SFAs reached significant levels (p < 0.05). The content of eicosapentaenoic acid (EPA) in the meat of Taihu pigeons was significantly higher than that in other breeds. In conclusion, compared with the White King pigeon, the meat of local breed pigeons (Taihu pigeon, Shiqi pigeon, Tarim pigeon, and Boot pigeon) had dark flesh, good water retention, high protein and inosine contents, a high proportion of essential amino acids, and a low saturated fatty acid ratio. In addition, Taihu pigeons had the highest protein content (22.72%), monounsaturated fatty acids (44.58%), and EPA (0.47%) compared to other breeds.

Overexpression of Myrothamnus flabellifolia MfWRKY41 confers drought and salinity tolerance by enhancing root system and antioxidation ability in Arabidopsis.

Myrothamnus flabellifolia is the only woody resurrection plant discovered so far and could recover from extreme desiccation condition. However, few genes related to its strong drought tolerance have been characterized, and the underlying molecular mechanisms remains mysterious. Members of WRKY transcription factor family are effective in regulating abiotic stress responses or tolerance in various plants. An early dehydration-induced gene encoding a WRKY transcription factor namely MfWRKY41 was isolated from M. flabellifolia, which is homologous to AtWRKY41 of Arabidopsis. It contains a typical WRKY domain and zinc finger motif, and is located in the nucleus. Comparing to wild type, the four transgenic lines overexpressing MfWRKY41 showed better growth performance under drought and salt treatments, and exhibited higher chlorophyll content, lower water loss rate and stomatal aperture and better osmotic adjustment capacity. These results indicated that MfWRKY41 of M. flabellifolia positively regulates drought as well as salinity responses. Interestingly, the root system architecture, including lateral root number and primary root length, of the transgenic lines was enhanced by MfWRKY41 under both normal and stressful conditions, and the antioxidation ability was also significantly improved. Therefore, MfWRKY41 may have potential application values in genetic improvement of plant tolerance to drought and salinity stresses. The molecular mechanism involving in the regulatory roles of MfWRKY41 is worthy being explored in the future.

Heterologous Expression of MfWRKY7 of Resurrection Plant Myrothamnus flabellifolia Enhances Salt and Drought Tolerance in Arabidopsis.

Drought and salinity have become major environmental problems that affect the production of agriculture, forestry and horticulture. The identification of stress-tolerant genes from plants adaptive to harsh environments might be a feasible strategy for plant genetic improvement to address the challenges brought by global climate changes. In this study, a dehydration-upregulated gene MfWRKY7 of resurrection Plant Myrothamnus flabellifolia, encoding a group IId WRKY transcription factor, was cloned and characterized. The overexpression of MfWRKY7 in Arabidopsis increased root length and tolerance to drought and NaCl at both seedling and adult stages. Further investigation indicated that MfWRKY7 transgenic plants had higher contents of chlorophyll, proline, soluble protein, and soluble sugar but a lower water loss rate and malondialdehyde content compared with wild-type plants under both drought and salinity stresses. Moreover, the higher activities of antioxidant enzymes and lower accumulation of O2− and H2O2 in MfWRKY7 transgenic plants were also found, indicating enhanced antioxidation capacity by MfWRKY7. These findings showed that MfWRKY7 may function in positive regulation of responses to drought and salinity stresses, and therefore, it has potential application value in genetic improvement of plant tolerance to abiotic stress.

Do moss sporophytes maintain water balance? New insights from sporophyte water relations and the wild maturation cycle in Funaria hygrometrica Hedw.

ABSTRACT Introduction The water relations of Funaria hygrometrica Hedw. sporophytes have never been investigated, although unchanged morphology through periods of drought suggests that they may be homoiohydric. Knowledge of the sporophyte maturation cycle is also incomplete and based on glasshouse plants. Methods We followed sporophyte development in wild populations of Funaria, recording fresh weights of every phenophase. Rates of water loss under laboratory conditions from sporophytes of different ages were recorded, and the ontogeny of the intercellular spaces and the maturational deposition of extra wall materials and waxes were investigated by cryo-SEM. Key results The sporophyte maturation cycle in wild Funaria lasted from December until July (> 200 days), nearly three times that recorded in glasshouses. Fresh weights of green capsules increased until after sporogenesis. Mature brown capsules were highly dehydrated. Prevailing weather conditions or addition of water had no effect on weights. Low rates of water loss, comparable with those from vascular plant leaves, decreased throughout sporophyte maturation under laboratory conditions. These data indicate that Funaria sporophytes mirror homoiohydric vascular plants. Deposition of additional wall materials around the stomatal apertures prevents closure soon after their opening towards the end of post-meiosis capsule expansion. Conclusions With phenophases similar to those of perennial species, Funaria may not be as much a fugitive species as previously assumed. The very brief window in nascent stomata ontogeny when reversible aperture changes might be possible indicates that the likely principal role of Funaria stomata is facilitation of capsule dehydration and not active regulation of gaseous exchange.

THERMAL BIOLOGY OF A POPULATION OF Xenosaurus newmanorum (SQUAMATA: XENOSAURIDAE) FROM XILITLA, SAN LUIS POTOSÍ, MEXICO: DO THEY ACTIVELY THERMOREGULATE?

The knob-scaled lizards (family Xenosauridae) comprise a clade of crevice-dwelling North American lizards with a trend towards low body temperature and high rates of water loss, and are often regarded as thermoconformers. However, there are few studies on their thermal ecology, most of them limited to documenting the body temperatures and their relation with environmental temperatures. Here, we documented the field body temperatures (Tb), selected temperatures (Tset), operative temperatures (Te), thermoregulatory effectiveness, and thermal tolerances of 10 individuals of the Newman’s Knob-scaled Lizard, Xenosaurus newmanorum, collected in the fall of 2017 in La Huasteca region of Mexico. Mean Tb was 22.75 °C and mean Tset 25.08 °C (1.64 °C and 3.97 °C above mean Te, respectively). The species had a relatively narrow thermal tolerance range (25.89 °C). Furthermore, based on two different thermoregulatory indexes, we found direct evidence of active thermoregulation in X. newmanorum. This constitutes the first record of active thermoregulation in a xenosaurid from a low-elevation environment and the second record of thermal tolerances. We discuss on the thermal strategies of other species of the genus and pose that active thermoregulation might be more widespread in Xenosaurus than previously thought.

Trait Selection for Yield Improvement in Foxtail Millet (Setaria italica Beauv.) under Climate Change in the North China Plain

Weather factors and drought could impact the yield of foxtail millet, and varieties with traits that could alleviate the negative effects of deteriorating weather factors in the future should be developed. A total of 25 foxtail millet varieties were evaluated in experiments from 2016 to 2020 under well-watered (WW) and water-stressed (WS) treatments. Future climate change might favor an increased temperature that impedes grain yield, so varieties with characters that are less sensitive to temperature change are preferred. Varieties with a high panicle dry-weight per plant, thousand grain weight, leaf area and water productivity in deep soil layer usually gave better grain production under both water treatments. Under the WW treatment, low grain abortion rate, optimal chlorophyll and canopy temperature and more roots in the upper soil layer could favor a high yield and drought resistance. Under the WS treatment, varieties with a high harvest index, low rate of water loss and more roots in the upper soil layer usually produced a high yield.

Preparation and characterization of natamycin-incorporated agar film and its application on preservation of strawberries

This study investigated the preparation and characterization of Natamycin-incorporated agar film and its antimicrobial effect on preserve quality of fresh strawberries. Natamycin-incorporated agar films were prepared by solvent casting method and characterized in mechanical, optical, water swelling, and barrier properties. Antimicrobial activity of the films and their preservative effects on strawberries stored at 4 °C and 20 °C were also assessed. As natamycin amount increased (0%, 0.33%, 0.66%, 0.99%, 1.33%, w/w of dry film), the antimicrobial activity of the film increased with inhibition zone of Aspergillus niger and Saccharomyces cerevisiae from 0 cm to approximate 28 cm, while there was no significant effect on water vapor permeability and swelling degree. On the other hand, with the increase of natamycin, tensile strength of the film declined (from 17.61 to 14.94 MPa), while oxygen permeability enhanced from 0.161 to 0.585 × 10−15 cm3 cm/cm2 s Pa. Furthermore, the natamycin can be released quickly from antimicrobial films within 2 days under aqueous solution in accordance with fick’s law. Along with the addition of natamycin, light transmittance of antimicrobial films trends to decrease whereas the haze and total color difference of film increase significantly. Compared to control group, fungal colony number of strawberry packaged in antimicrobial film was reduced by 0.51 and 1.05 log cfu g−1 at 4 °C and 20 °C, respectively. The strawberries packaged by antimicrobial film retained high total soluble solid content with higher hardness of 61.89% and 54.47% at 4 °C and 20 °C, respectively at the end of storage. Moreover, strawberries packaged with the natamycin-incorporated film showed lower rate of water loss during storage (1.43% and 7.66% at 4 °C and 20 °C, respectively). The obtained results indicate that natamycin-incorporated agar film could be used as environment-friendly packaging alternative to preserve perishable fresh produce and extend their shelf lives by means of antimicrobial activity and other merits.

GmSAP5, a soybean A20/AN1 domain-containing stress-associated protein gene activated by GmAREB3, increases drought stress resistance in soybean by mediating ABA signaling

Drought stress impairs crop growth and productivity. Stress-associated proteins (SAPs), a class of zinc finger proteins containing the A20/AN1 domain, function in various stress responses in plants. However, little is known about the function of SAPs in drought-stress responses in soybean, an oil and protein crop. We report that a GmSAP5 protein confers drought tolerance by increasing sensitivity to abscisic acid (ABA) and reducing stomatal aperture. Overexpression and RNA interference of GmSAP5 in soybean hairy roots resulted in elevated resistance and sensitivity to drought stress, respectively. ABA and proline contents increased in GmSAP5-overexpressing plants under water-deficit conditions. Lower water loss rates and higher relative water contents were observed in GmSAP5-overexpressing plants, resulting in increased drought-stress resistance. A yeast one-hybrid assay and luciferase transient transcriptional activity assay showed that GmAREB3, an AREB/ABF transcription factor, could bind to the promoter of GmSAP5 and activate its expression. These results suggest that GmSAP5 acts downstream of GmAREB3 and improves drought-stress resistance by mediating ABA signaling.

MiR2105 and the kinase OsSAPK10 co-regulate OsbZIP86 to mediate drought-induced ABA biosynthesis in rice.

Mediating induced abscisic acid (ABA) biosynthesis is important for enhancing plant stress tolerance. Here, we found that rice (Oryza sativa L.) osa-miR2105 (miR2105) and the Stress/ABA-activated protein kinase (OsSAPK10) coordinately regulate the rice basic region-leucine zipper transcription factor (bZIP TF; OsbZIP86) at the posttranscriptional and posttranslational levels to control drought-induced ABA biosynthesis via modulation of rice 9-cis-epoxycarotenoid dioxygenase (OsNCED3) expression. OsbZIP86 expression is regulated by miR2105-directed cleavage of the OsbZIP86 mRNA. OsbZIP86 encodes a nuclear TF that binds to the promoter of the ABA biosynthetic gene OsNCED3. OsSAPK10 can phosphorylate and activate OsbZIP86 to enhance the expression of OsNCED3. Under normal growth conditions, altered expression of miR2105 and OsbZIP86 displayed no substantial effect on rice growth. However, under drought conditions, miR2105 knockdown or OsbZIP86 overexpression transgenic rice plants showed higher ABA content, enhanced tolerance to drought, lower rates of water loss, and more stomatal closure of seedlings, compared with wild-type rice Zhonghua 11; in contrast, miR2105 overexpression, OsbZIP86 downregulation, and OsbZIP86 knockout plants displayed opposite phenotypes. Collectively, our results show that the "miR2105-(OsSAPK10)-OsbZIP86-OsNCED3" module regulates the drought-induced ABA biosynthesis without penalty on rice growth under normal conditions, suggesting candidates for improving drought tolerance in rice.

Laccase-catalyzed surface oxidation of poly(2-hydroxyethyl methacrylate) contact lens hydrogel using polyvinylamine-graft-TEMPO as mediator

Surface oxidation is a commonly used surface modification method for macromolecular biomaterials, which can increase the surface hydrophilicity and biocompatibility, and provide active sites for subsequent functional modifications. The nitroxyl radical, as represented by TEMPO, could act as an electron transfer mediator in the catalytic oxidation reaction in aqueous phase. By immobilizing TEMPO on a water-soluble polymer carrier polyvinylamine (PVAm) and using laccase as a catalyst, the surface of poly(2-hydroxyethyl methacrylate) (pHEMA) contact lens hydrogel can be selectively oxidized. Herein, polyvinylamine-graft-TEMPO was used as a polymeric electron transfer mediator to confine the oxidation reaction within the surface of the pHEMA hydrogel. The oxidized hydrogel with surface aldehydes was subsequently coated with hyaluronic acid, which gained low rate of water loss and low protein adsorption. This surface oxidation method can provide new ways for the activation, modification, and function expansion for the surface of polymeric biomaterials especially contact lens hydrogels.

Transcriptional activation of rice CINNAMOYL-CoA REDUCTASE 10 by OsNAC5, contributes to drought tolerance by modulating lignin accumulation in roots.

SummaryDrought is a common abiotic stress for terrestrial plants and often affects crop development and yield. Recent studies have suggested that lignin plays a crucial role in plant drought tolerance; however, the underlying molecular mechanisms are still largely unknown. Here, we report that the rice (Oryza sativa) gene CINNAMOYL‐CoA REDUCTASE 10 (OsCCR10) is directly activated by the OsNAC5 transcription factor, which mediates drought tolerance through regulating lignin accumulation. CCR is the first committed enzyme in the monolignol synthesis pathway, and the expression of 26 CCR genes was observed to be induced in rice roots under drought. Subcellular localisation assays revealed that OsCCR10 is a catalytically active enzyme that is localised in the cytoplasm. The OsCCR10 transcript levels were found to increase in response to abiotic stresses, such as drought, high salinity, and abscisic acid (ABA), and transcripts were detected in roots at all developmental stages. In vitro enzyme activity and in vivo lignin composition assay suggested that OsCCR10 is involved in H‐ and G‐lignin biosynthesis. Transgenic rice plants overexpressing OsCCR10 showed improved drought tolerance at the vegetative stages of growth, as well as higher photosynthetic efficiency, lower water loss rates, and higher lignin content in roots compared to non‐transgenic (NT) controls. In contrast, CRISPR/Cas9‐mediated OsCCR10 knock‐out mutants exhibited reduced lignin accumulation in roots and less drought tolerance. Notably, transgenic rice plants with root‐preferential overexpression of OsCCR10 exhibited higher grain yield than NT controls plants under field drought conditions, indicating that lignin biosynthesis mediated by OsCCR10 contributes to drought tolerance.

SlNAC6, A NAC transcription factor, is involved in drought stress response and reproductive process in tomato

Tomato plants are susceptible to drought stress, but the mechanism involved in this process still remains poorly understood. In the present study, we demonstrated that SlNAC6, a nuclear-localized protein induced by exogenous abscisic acid (ABA) or polyethylene glycol (PEG) stress treatment, plays a positive role in tomato plant response to PEG stress. Down-regulation of SlNAC6 (SlNAC6-RNAi) resulted in a semidwarf phenotype, and the SlNAC6-RNAi lines showed reduced tolerance to PEG stress, exhibiting a higher water loss rate and degree of oxidative damage, as well as lower values of proline content and antioxidant enzyme activity, when compared with those in wild type (WT). In contrast, overexpression of SlNAC6 (SlNAC6-OE) leads to a significant delay of growth, and the SlNAC6-OE lines showed greatly enhanced tolerance to PEG stress concomitant with a lower water loss rate and degree of oxidative damage, as well as higher values of proline content and antioxidant enzyme activity. Further study showed that the transcription level of ABA signaling-related genes and the ABA content are respectively decreased or increased in SlNAC6-RNAi and SlNAC6-OE seedlings, as verified by multiple physiological parameters, such as stomatal conductance, water loss rate, seed germination, and root length. Moreover, overexpression of SlNAC6 can accelerate tomato fruit ripening. Collectively, this study demonstrates SlNAC6 exerts important roles in tomato development, drought stress response, and fruit ripening processes, some of them perhaps partly through modulating an ABA-mediated pathway, which implies SlNAC6 may hold the potential applications in improving agronomic traits of tomato or other Solanaceae crops.