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Effectors secreted by the bacterial type III system play a central role in the interaction between Gram-negative bacterial pathogens and their host plants. Recent advances in the effector studies have helped cementing several key concepts concerning bacterial pathogenesis, plant immunity, and plant–pathogen co-evolution. Type III effectors use a variety of biochemical mechanisms to target specific host proteins or DNA for pathogenesis. The identifications of their host targets led to the identification of novel components of plant innate immune system. Key modules of plant immune signaling pathways such as immune receptor complexes and MAPK cascades have emerged as a major battle ground for host–pathogen adaptation. These modules are attacked by multiple type III effectors, and some components of these modules have evolved to actively sense the effectors and trigger immunity. [Copyright &y& Elsevier]

Abstract: A wheat (Triticum aestivum L., near isogenic line of Hamlet) O-methyltransferase (OMT) was previously reported as a putative caffeic acid OMT (TaCOMT1), involved in lignin biosynthesis, based on its high sequence similarity with a number of graminaceous COMTs. The fact that the putative TaCOMT1 exhibits a significantly high sequence homology to another recently characterized wheat flavone-specific OMT (TaOMT2), and that molecular modeling studies indicated several conserved amino acid residues involved in substrate binding and catalysis of both proteins, prompted an investigation of its appropriate substrate specificity. We report here that TaCOMT1 exhibits highest preference for the flavone tricetin, and lowest activity with the lignin precursors, caffeic acid/5-hydroxyferulic acid as the methyl acceptor molecules, indicating that it is not involved in lignin biosynthesis. We recommend its reannotation to a flavone-specific TaOMT1 that is distinct from TaOMT2. [Copyright &y& Elsevier]

Like animals, plants sense bacterial pathogens through surface-localized pattern recognition receptors (PRRs) and intracellular nucleotide-binding leucine-rich repeat proteins (NB-LRR) and trigger defense responses. Many plant-pathogenic bacteria secrete a large repertoire of effector proteins into host cells to modulate host responses, enabling successful infection and multiplication in plants. A number of these effector proteins target plant innate immunity signaling pathways, while others induce specific host genes to enhance plant susceptibility. Substantial progress has been made in the past two years concerning biochemical function of effectors and their host targets. These advances provide new insights into regulatory mechanisms of plant immunity and host–pathogen co-evolution. [Copyright &y& Elsevier]

This study was designed to evaluate the effect of dietary Ser on performance, egg quality, serum indices, and ileal mucosal immunity in laying hens fed low crude protein (LCP), essential amino acids (EAA) balanced diets. A total of 480 Hy-Line Brown layers at 24 wk of age were randomly assigned into 5 dietary treatments with 8 replicates of 12 birds each. Treatments included a control diet (16.49% CP), and 4 LCP, EAA balanced diets (14.05% CP) supplemented with 0, 0.114%, 0.306%, 0.498% L-Ser, respectively. Dietary Ser supplementation linearly increased hen-day egg production (HDEP ; P < 0.05) and decreased feed-to-egg ratio (P < 0.05) among LCP groups from wk 6 to 10, and the optimal HDEP of layers occurred at Ser level of 0.498%. At the end of wk 10, birds in the control had higher albumen height and thick white proportion than those fed the LCP diet without Ser addition (P < 0.05), and presented a lower yolk color score than all LCP groups (P < 0.05). Among LCP groups, serum total protein and globulin contents were significantly increased by dietary Ser addition at the levels of 0.306% and 0.498% (P < 0.05), and had a linear response to the supplemental Ser levels (P < 0.05). Furthermore, dietary 0.498% Ser supplementation significantly increased serum immunoglobulin G and immunoglobulin M contents (P < 0.05) and up-regulated the expression of mucin 2, secretory immunoglobulin A, and relevant glycosyltransferases of O-glycosylation in ileal mucosa (P < 0.05). The increased expression of proinflammatory cytokines IFN-γ and IL-1β induced by LCP diets (P < 0.05) was reversed following 0.498% Ser addition (P < 0.05). Collectively, dietary CP reduction by 2.44% could maintain the productive performance of layers when it was fortified with certain EAA, though poor albumen quality, and ileal inflammation were occurred. The addition of Ser to LCP diets improved performance probably through enhancing humoral and ileal mucosal immunity and attenuating the ileal inflammation of layers. [ABSTRACT FROM AUTHOR]

In photosynthetic cells, chloroplasts and mitochondria are the sites of the core redox reactions underpinning energy metabolism. Such reactions generate reactive oxygen species (ROS) when oxygen is partially reduced. ROS signaling leads to responses by cells which enable them to adjust to changes in redox status. Recent studies in Arabidopsis thaliana reveal that chloroplast NADH can be used to generate malate which is exported to the mitochondrion where its oxidation regenerates NADH. Oxidation of this NADH produces mitochondrial ROS (mROS) which can activate signaling systems to modulate energy metabolism, and in certain cases can lead to programmed cell death (PCD). We propose the term 'malate circulation' to describe such redistribution of reducing equivalents to mediate energy homeostasis in the cell. The malate valve has long been proposed to release excess reducing equivalents from the chloroplast, but mutants lacking the proposed key enzyme NADP-dependent malate dehydrogenase show little impairment of chloroplast function, suggesting the involvement of an alternative pathway. New research suggests a central role for a malate valve, employing chloroplast NAD-dependent malate dehydrogenase, which also has additional non-enzymatic functions in chloroplast biogenesis. The new malate circulation model proposes that malate exported from the chloroplast is oxidized in the mitochondrion triggering ROS production, which can modulate growth and ultimately induce cell death. It is proposed that the chloroplast to mitochondrion (CTM) pathway in conjunction with direct import of NAD+ leads to elevated levels of NADH in the mitochondrion. [ABSTRACT FROM AUTHOR]

The decline in albumen quality resulting from aging hens poses a threat to the financial benefits of the egg industry. Exploring the underlying mechanisms from the perspective of cell molecules of albumen formation is significant for the efficient regulation of albumen quality. Two individual groups of Hy-Line Brown layers with ages of 40 (W40) and 100 (W100) wk old were used in the present study. Each group contained over 2,000 birds. This study assessed the egg quality, biochemical indicators and physiological status of hens between W40 and W100. Subsequently, a quantitative proteomic analysis was conducted to identify differences in protein abundance in magnum tissues between W40 and W100. In the W40 group, significant increases (P < 0.05) were notable for albumen quality (thick albumen solid content, albumen height, Haugh unit), serum indices (calcium, estrogen, and progesterone levels), magnum histomorphology (myosin light-chain kinase content, secretory capacity, mucosal fold, goblet cell count and proportion) as well as the total antioxidant capacity of the liver. However, the luminal diameter of the magnum, albumen gel properties and random coil of the albumen were increased (P < 0.05) in the W100 group. The activity of glutathione, superoxidase dismutase, and malondialdehyde in the liver, magnum, and serum did not vary (P > 0.05) among the groups. Proteomic analysis revealed the identification of 118 differentially expressed proteins between the groups, which comprised proteins associated with protein secretion, DNA damage and repair, cell proliferation, growth, antioxidants, and apoptosis. Furthermore, Kyoto Encyclopedia of Genes pathway analysis revealed that BRCA2 and FBN1 were significantly downregulated in Fanconi anemia (FA) and TGF-β signaling pathways in W100, validated through quantitative real-time PCR (qRT-PCR). In conclusion, significant age-related variations in albumen quality, and magnum morphology are regulated by proteins involved in antioxidant capacity. [ABSTRACT FROM AUTHOR]

Large-scale glacier area expansion or shrinkage is among the most conspicuous indicators of regional and global climate change. Glacier extraction from satellite images is an essential step in large-scale area change monitoring. However, glacier extraction is usually influenced by cloud cover and seasonal snow, and thus far, there is no effective and automatic method to monitor glacier area change in large regions. In this study, a new method 'multi-temporal minimum NDSI composite' is proposed for clean glacier and nonseasonal snow extraction, and the results agree well with the glacier inventory (excluding the debris part), except in Himalayan regions where non-seasonal snow exists widely out of glaciers. This method is also used to estimate the glacier and nonseasonal snow area changes in High Mountain Asia (HMA) over the past 29 years. With this method, we can use abundant Landsat images of summer seasons from continuous years to composite a cloud-free and seasonal snow-free glacial image pixel by pixel. Glacial maps for the whole HMA are produced every 10 years beginning in 1990, so glacier changes are presented in different subregions and periods. The number of images which is used to composite a glacial map in each pixel is also given for uncertainty analysis. According to the results, the clean glacier and nonseasonal snow area in HMA decreased by −0.43 ± 0.19%/a during 1990–2018 but had high temporal and spatial heterogeneity. Clean glacier and nonseasonal snow area decreased rapidly during 1990–2000, slowed down during 2000–2010, and then sped up during 2010–2018. The fastest reductions were in Hengduan Shan at rates of approximately −1.05 ± 0.09%/a, and the only area with growth (at a rate of 0.50 ± 0.11%/a) was in West Kun Lun during 1990–2018. • A new method 'multi-temporal minimum NDSI composite' for glacier area is proposed. • The clean glacier and firn area in HMA decreased by 0.43 ± 0.19%/a during 1990–2018. • The area decreased rapidly in 1990–2000 and 2010–2018, slowly in 2000–2010. • The fastest area reductions were in the Hengduan Shan during 1990–2018. • The only area with growth was in the West Kun Lun during 1990–2018. [ABSTRACT FROM AUTHOR]

• The appropriate and top limit additions of Mn in amino acid-complexed form in laying hen diet were determined. • The investigated Mn supplementation levels ranged from 20 to 800 mg/kg. • The dietary supplementation of amino acid-complexed Mn more than 400 mg/kg had adverse effect on kidney of laying hens. • The appropriate inclusion of Mn from Mn-amino acid complexes could be 40 mg/kg (21.95 mg/kg in basal diet) for laying hens. The current study was conducted to evaluate the effects of long-term dietary supplementation of amino acid-complexed manganese (Mn) on production performance, egg quality, blood biochemistry and organ histopathology in laying hens. A total of 756 Hy-Line Brown layers were randomly assigned into 7 dietary groups with 6 replicates. Each replicate contained 18 birds. Layers were fed a basal diet (Mn, 21.95 mg/kg) or the basal diet supplemented with 20, 40, 80, 120, 400 or 800 mg/kg Mn in amino acid-complexed form, respectively. The feeding trial lasted for 24 wks. Compared with the basal diet (control), dietary supplementation with 80 mg/kg Mn increased egg production and decreased feed conversion ratio (FCR) during 1–12 and 1–24 wk (P < 0.05). Manganese supplementation at 40 mg/kg increased egg production (1–12, 13–24 and 1–24 wk), egg mass (13–24 and 1–24 wk), and decreased FCR (13–24 and 1–24 wk, P < 0.05). Higher values of eggshell breaking strength were observed in dietary Mn addition ≥20 mg/kg treatments (P < 0.05) at different sampling time points, and they occurred in 40 mg/kg more frequently than any other Mn supplementation level. Dietary supplementation of 40 or 80 mg/kg Mn increased total superoxide dismutase (T-SOD) activity in serum (P < 0.05), but this benefit diminished when the inclusion exceeded 120 mg/kg. Besides, higher values of white blood cell (WBC), platelet and creatinine occurred in 400 and 800 mg/kg Mn addition groups (P < 0.05), accompanied with local inflammation of kidney tissues. In conclusion, dietary supplementation with Mn can improve productive performance, eggshell breaking strength and redox status, at a level of 40 mg/kg from Mn-amino acid complexes, and overdose of Mn supplementation (≥ 400 mg/kg) would cause detrimental effects to Hy-Line Brown laying hens. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) are widely produced in different cellular compartments under both biotic and abiotic stress conditions. ROS play a central role in plant signaling and regulate diverse cellular processes. Recent advances are shedding new light on sophisticated mechanisms controlling ROS biogenesis and signaling in plant immunity. In this review, we summarize our current understanding of the regulation of apoplastic ROS production in response to microbial molecular patterns and draw comparison with abscisic acid (ABA)-induced apoplastic ROS. We also discuss how ROS act as signal molecules to regulate cellular activities using stomatal movement as an example. [ABSTRACT FROM AUTHOR]

Abstract: Debris cover is widely present in the ablation areas of mountain glaciers. Such debris plays an important role in glacier mass balance, but it complicates the glacier boundary and area estimation when using remotely sensed images. Automatic recognition of the debris is much more difficult than recognizing bare ice on optical remotely sensed images because the debris has almost the same spectral characteristics of the surrounding terrain. In this paper, the scattering characteristics of the debris on the C- and L-band polarimetric SAR images are presented and analyzed to study the possibility of recognizing debris thickness and extent. The Koxkar glacier, in the central Tianshan Mountain Range, was selected as the study area. It was found that debris is distinct from bare ice in cross polarization (HV) of both the L- and C-bands. The L-band volume scattering component, acquired from target decomposition, increases with debris thickness when the debris is less than 25cm deep, but the volume scattering does not increases if the debris is thicker than 25cm. In contrast, the C-band SAR data does not appear to be sensitive to debris thickness. This difference may be caused by different radar penetration depth of the debris. On the basis of the polarimetric property analysis, two methods were developed to determine the extent of the debris. In the first method, the simple threshold to distinguish debris from non-debris areas is presented. Using this threshold, approximately 90% of the debris can be recognized. In the second method, by combining more polarimetric features and support vector machines, recognition of debris reaches an accuracy greater than 95%. [Copyright &y& Elsevier]

Abstract: Small glaciers and ice caps in mountainous areas are often sensitive indicators of local and global climate change. In this paper, typical continental glaciers, the Dongkemadi and its neighbouring glaciers in the central area of the Qinghai–Tibetan Plateau, are monitored using multi-sensor C-band synthetic aperture radar (SAR) imagery. The study includes analysis of the alternating processes of ablation and freezing, the glacier zones detected on SAR images, and the changing snow/firn line across different days, seasons, and years. Experiments show that in late summer the wet snow-/firn-ice boundary, which is termed the late summer wet snow/firn line (WSFL) is easily detected on SAR images and it is relatively stable over multiple days. Also, the detected late summer WSFL, and the recorded yearly equilibrium line which reflects glacier mass balance, are close in a positive mass balance year, but the detected late summer WSFL is lower than the equilibrium line in a negative mass balance year. By combining pit and SAR observations it was found that the firn can be divided into two parts on the glaciers; the thick firn that lies in the neve basin is distinct on SAR images in winter, but the firn surrounding the basin with thickness ranging from 0 to 20cm is difficult to recognize. The thick firn line (the lower boundary of neve basin) is stable in observations eight years apart. Based on the C-band VV polarization SAR image experiments, field work, and existing records, the spatiotemporal backscatter signature specific to the typical continental glacier is identified. The spatiotemporal backscatter signature helps to understand mass balance proxies and surface melt patterns of the glaciers in SAR images. [Copyright &y& Elsevier]

This study investigated the effects of dietary chloride (Cl) reduction on laying performance and eggshell quality by substitution of sodium bicarbonate (NaHCO 3) or sodium sulfate (Na 2 SO 4) for part of dietary sodium chloride (NaCl), and further explored its mechanism for improving eggshell quality. A total of 360 29-wk-old Hy-line Brown laying hens were randomly allocated to 5 dietary treatments, including a basal diet contained 0.33% NaCl (control group, 0.27% dietary Cl), and 4 experimental diets that contained 0.21% and 0.15% dietary Cl by substituting Na 2 SO 4 or NaHCO 3 for part of NaCl in the basal diet. No significant differences were observed in blood Na+, Cl−, K+ and Ca2+ levels and pH value as well as serum creatinine and uric acid contents among 5 treatments (P > 0.05). Dietary Cl reduction increased egg production and ADFI during wk 33 to 36, 37 to 40 and 29 to 40 of age and decreased feed conversion ratio during wk 37 to 40 of age (P < 0.05). The hens fed with diets containing 0.15% Cl increased eggshell breaking strength, thickness and weight ratio in wk 40 of age (P < 0.05). Birds fed with dietary 0.21% and 0.15% Cl exhibited higher effective layer thickness and lower mammillary layer thickness of eggshell than those fed with dietary 0.27% Cl (P < 0.05). Apparent Ca metabolizability of hens was increased with dietary Cl reduction (P < 0.05). Total Ca of eggshell of dietary 0.15% Cl group was higher than that of dietary 0.27% Cl group (P < 0.05). No significant differences in laying performance, eggshell quality and Ca metabolism of layers were observed between Na 2 SO 4 and NaHCO 3 replacement groups (P > 0.05). Overall, dietary Cl reductions could improve laying performance and eggshell quality by substitution of NaHCO 3 or Na 2 SO 4 for part of NaCl, and there were no differences in the improvements between these two substitutes. The improved eggshell quality may be attributed to improved eggshell ultrastructure and increased supply of eggshell Ca 2 CO 3. [ABSTRACT FROM AUTHOR]

The redox-based protein S -nitrosylation is a conserved mechanism modulating nitric oxide (NO) signaling and has been considered mainly as a non-enzymatic reaction. S -nitrosylation is regulated by the intracellular NO level that is tightly controlled by S -nitrosoglutathione reductase (GSNOR). However, the molecular mechanisms regulating S -nitrosylation selectivity remain elusive. Here, we characterize an Arabidopsis " repressor of " gsnor1 (rog1) mutation that specifically suppresses the gsnor1 mutant phenotype. ROG1, identical to the non-canonical catalase, CAT3, is a transnitrosylase that specifically modifies GSNOR1 at Cys-10. The transnitrosylase activity of ROG1 is regulated by a unique and highly conserved Cys-343 residue. A ROG1C343T mutant displays increased catalase but decreased transnitrosylase activities. Consistent with these results, the rog1 mutation compromises responses to NO under both normal and stress conditions. We propose that ROG1 functions as a transnitrosylase to regulate the NO-based redox signaling in plants. • ROG1 or CAT3 acts as a transnitrosylase to regulate NO signaling in plants • Cysteine-343 is vital for ROG1 activity • ROG1 transnitrosylates GSNOR1 to regulate its stability • rog1 mutants have reduced sensitivity to NO under normal and stress conditions Chen et al. identify and characterize the non-canonical catalase ROG1/CAT3 as a transnitrosylase in Arabidopsis. ROG1 contains a highly conserved cysteine-343, which is crucial for its activity, and ROG1 transnitrosylates GSNOR1 to regulate its stability. ROG1 regulates NO signaling under both normal and stress conditions. [ABSTRACT FROM AUTHOR]

Cold stress adversely affects plant growth, development, and crop productivity and quality. Plants employ cold acclimation strategy to protect them from cold damage. The transcription-factor-CBF-dependent cold signaling pathway plays a key role in plant cold acclimation. However, how this signaling pathway is dynamically and precisely regulated remains unknown. Here, we report that two U-box type E3 ubiquitin ligases, PUB25 and PUB26, positively regulate freezing tolerance in Arabidopsis thaliana. Both PUB25 and PUB26 poly-ubiquitinate MYB15, a transcriptional repressor of the CBF-dependent cold signaling pathway, leading to MYB15 degradation and thus enhanced CBF expression under cold stress. Furthermore, cold-activated OST1 specifically phosphorylates PUB25 and PUB26 at conserved threonine residues, enhancing their E3 activity and facilitating the cold-induced degradation of MYB15. Our results thus unravel the regulatory role of the OST1-PUB25/26 module in regulating the duration and amplitude of the cold response by controlling the homeostasis of the negative regulator MYB15. • U-box E3 ligases PUB25 and PUB26 positively regulate freezing tolerance • PUB25 and PUB26 target MYB15 transcription factor for degradation under cold stress • Cold-activated OST1 phosphorylates PUB25 and PUB26 to enhance their E3 activity Wang et al. show that the U-box E3 ligases PUB25 and PUB26 are phosphorylated by OST1 to enhance their E3 activity. The ligases promote the degradation of MYB15, a key upstream negative regulator of CBF genes, thereby positively regulating freezing tolerance in plants. [ABSTRACT FROM AUTHOR]