Trends in maize (Zea mays L.) phenology and sensitivity to climate factors in China from 1981 to 2010.

Changes in crop phenology may reflect crop responses and adaptation to climate change. In this study, we used observational data (1981-2010) of maize (Zea mays L.) phenology from agricultural meteorological stations in the major maize-growing regions of China to examine spatiotemporal changes in the phenologies and growth periods and associated sensitivities to changes in major climatic factors. The results showed that, during the study period, sowing, tasseling, and maturity dates for maize were delayed in most maize growth regions. The lengths of vegetative growth period (VGP, from emergence to tasseling) were increased in spring and spring-summer maize growth regions and decreased in summer maize growth regions; the lengths of the maize reproductive growth period (RGP, from tasseling to maturity) and whole growth period (WGP, from emergence to maturity) were mostly extended (except NWMR_SU). Overall, sensitivity of maize VGP, RGP, and WGP was negatively related to average temperature (P < 0.01) and positively related to precipitation and sunshine hours (P < 0.01); there were variations in sensitivity among regions and data station locations. Precipitation was a driver of growth period length in the northwest inland maize region, whereas mean temperature and sunshine hours were drivers in the southwest hilly region.

CLE9 peptide-induced stomatal closure is mediated by abscisic acid, hydrogen peroxide, and nitric oxide in Arabidopsis thaliana.

CLE peptides have been implicated in various developmental processes of plants and mediate their responses to environmental stimuli. However, the biological relevance of most CLE genes remains to be functionally characterized. Here, we report that CLE9, which is expressed in stomata, acts as an essential regulator in the induction of stomatal closure. Exogenous application of CLE9 peptides or overexpression of CLE9 effectively led to stomatal closure and enhanced drought tolerance, whereas CLE9 loss-of-function mutants were sensitivity to drought stress. CLE9-induced stomatal closure was impaired in abscisic acid (ABA)-deficient mutants, indicating that ABA is required for CLE9-medaited guard cell signalling. We further deciphered that two guard cell ABA-signalling components, OST1 and SLAC1, were responsible for CLE9-induced stomatal closure. MPK3 and MPK6 were activated by the CLE9 peptide, and CLE9 peptides failed to close stomata in mpk3 and mpk6 mutants. In addition, CLE9 peptides stimulated the induction of hydrogen peroxide (H2 O2 ) and nitric oxide (NO) synthesis associated with stomatal closure, which was abolished in the NADPH oxidase-deficient mutants or nitric reductase mutants, respectively. Collectively, our results reveal a novel ABA-dependent function of CLE9 in the regulation of stomatal apertures, thereby suggesting a potential role of CLE9 in the stress acclimatization of plants.

Strigolactone-triggered stomatal closure requires hydrogen peroxide synthesis and nitric oxide production in an abscisic acid-independent manner.

Accumulating data indicate that strigolactones (SLs) are implicated in the response to environmental stress, implying a potential effect of SLs on stomatal response and thus stress acclimatization. In this study, we investigated the molecular mechanism underlying the effect of SLs on stomatal response and their interrelation with abscisic acid (ABA) signaling. The impact of SLs on the stomatal response was investigated by conducting SL-feeding experiments and by analyzing SL-related mutants. The involvement of endogenous ABA and ABA-signaling components in SL-mediated stomatal closure was physiologically evaluated using genetic mutants. Pharmacological and genetic approaches were employed to examine hydrogen peroxide (H2 O2 ) and nitric oxide (NO) production. SL-related mutants exhibited larger stomatal apertures, while exogenous SLs were able to induce stomatal closure and rescue the more widely opening stomata of SL-deficient mutants. The SL-biosynthetic genes were induced by abiotic stress in shoot tissues. Disruption of ABA-biosynthetic genes, as well as genes that function in guard cell ABA signaling, resulted in no impairment in SL-mediated stomatal response. However, disruption of MORE AXILLARY GROWTH2 (MAX2), DWARF14 (D14), and the anion channel gene SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1) impaired SL-triggered stomatal closure. SLs stimulated a marked increase in H2 O2 and NO contents, which is required for stomatal closure. Our results suggest that SLs play a prominent role, together with H2 O2 /NO production and SLAC1 activation, in inducing stomatal closure in an ABA-independent mechanism.

Transcriptional regulation of receptor-like protein genes by environmental stresses and hormones and their overexpression activities in Arabidopsis thaliana.

Receptor-like proteins (RLPs) have been implicated in multiple biological processes, including plant development and immunity to microbial infection. Fifty-seven AtRLP genes have been identified in Arabidopsis, whereas only a few have been functionally characterized. This is due to the lack of suitable physiological screening conditions and the high degree of functional redundancy among AtRLP genes. To overcome the functional redundancy and further understand the role of AtRLP genes, we studied the evolution of AtRLP genes and compiled a comprehensive profile of the transcriptional regulation of AtRLP genes upon exposure to a range of environmental stresses and different hormones. These results indicate that the majority of AtRLP genes are differentially expressed under various conditions that were tested, an observation that will help to select certain AtRLP genes involved in a specific biological process for further experimental studies to eventually dissect their function. A large number of AtRLP genes were found to respond to more than one treatment, suggesting that one single AtRLP gene may be involved in multiple physiological processes. In addition, we performed a genome-wide cloning of the AtRLP genes, and generated and characterized transgenic Arabidopsis plants overexpressing the individual AtRLP genes, presenting new insight into the roles of AtRLP genes, as exemplified by AtRLP3, AtRLP11 and AtRLP28 Our study provides an overview of biological processes in which AtRLP genes may be involved, and presents valuable resources for future investigations into the function of these genes.

Hawthorn (Crataegus pinnatifida) berries ripeness induced pectin diversity: A comparative study in physicochemical properties, structure, function and fresh-keeping potential.

The effect of hawthorn berries ripeness on the physicochemical, structural and functional properties of hawthorn pectin (HP) and its potential in sweet cherry preservation were investigated. With the advanced ripeness of hawthorn berries, the galacturonic acid (GalA) content decreased from 59.70 mol% to 52.16 mol%, the molecular weight (Mw) reduced from 368.6 kDa to 284.3 kDa, the microstructure exhibited variable appearance from thick lamella towards porous cross-linked fragment, emulsifying activity and emulsions stability, antioxidant activities, α-amylase and pancreatic lipid inhibitory capacities significantly increased. The heated emulsion stored for 30 d presented higher creaming index and more ordered oil droplets compared to the unheated emulsion. With the extended berries ripeness, the firmness of HP gels remarkably decreased from 225.69 g to 73.39 g, while the springiness increased from 0.78 to 1.16, HP exhibited a superior inhibitory effect in water loss, browning, softening, and bacterial infection in sweet cherries preservation.

Copper-Catalyzed Asymmetric [3 + 2] Cycloaddition of N-2,2,2-Trifluoroethylisatin Ketimines to Access Three Classes of Polyfunctionalized Spiro-Pyrrolidine-Oxindole Motifs.

A facile copper-catalyzed [3 + 2] cycloaddition of N-2,2,2-trifluoroethylisatin ketimines with various electron-deficient alkenes to access structurally polyfunctionalized spiro-pyrrolidine-oxindole motifs has been developed. Under the catalytic system, the N-2,2,2-trifluoroethylisatin ketimines could be utilized to react with a series of exocyclic alkenes, including 2-acylamino acrylates, 3-methylene-ß-lactams, and sterically hindered cycloalkenes represented by cyclobutenone, to obtain a variety of densely functionalized spiro-pyrrolidine frameworks bearing an α-amino acid ester, ß-lactam, and cyclobutanone, respectively, in generally good yields with excellent diastereo- and enantioselectivities.

2,2'-Bipyridine-Enabled Photocatalytic Radical [4+2] Cyclization of N-Aryl-α-amino Acids for Synthesizing Polysubstituted Tetrahydroquinolines.

A facile photocatalytic radical [4+2] cyclization of N-aryl-α-amino acids with various alkenes to access structurally polysubstituted tetrahydroquinolines has been developed. Using a simple bipyridine as a catalyst, different N-aryl-α-amino acids could be utilized as the radical precursors to react with diverse electrophilic alkenes, including exocyclic terminal alkenes, acyclic terminal alkenes, and cycloalkenes, producing 10 types of nitrogen-containing heterocyclic compounds fused in multiple frameworks in generally moderate yields with good diastereoselectivities. Scale-up synthesis and transformations of the products further demonstrated the synthetic application of this protocol. Moreover, a decarboxylative radial pathway via a proton-coupled electron transfer process for illustration of this [4+2] cyclization was proposed on the basis of the control experiments. This process is highlighted by a simple bipyridine photocatalysis, mild reaction conditions, various N-aryl-α-amino acids and alkene materials, and application for the modification of natural products.

Iron(II)-Catalyzed Radical [3 + 2] Cyclization of N-Aryl Cyclopropylamines for the Synthesis of Polyfunctionalized Cyclopentylamines.

A facile iron(II)-catalyzed radical [3 + 2] cyclization of N-aryl cyclopropylamines with various alkenes to access the structurally polyfunctionalized cyclopentylamine scaffolds has been developed. Using low-cost FeCl2·4H2O as catalyst, N-aryl cyclopropylamines could be utilized to react with a wide range of alkenes including exocyclic/acyclic terminal alkenes, cycloalkenes, alkenes from the natural-occurring compounds (Alantolactone, Costunolide), and known drugs (Ibuprofen, l-phenylalanine, Flurbiprofen) to obtain a variety of cyclopentylamines fused with different useful motifs in generally good yields and diastereoselectivities. The highlight of this protocol is also featured by no extra oxidant, no base, EtOH as the solvent, gram-scale synthesis, and further diverse transformations of the synthetic products. More importantly, an iron(II)-mediated hydrogen radical dissociation pathway was proposed based on the mechanism research experiments.

An evidence update on the protective mechanism of tangeretin against neuroinflammation based on network pharmacology prediction and transcriptomic analysis.

Although the protective effects of tangeretin on neuroinflammation have been proven in cell and animal experiments, few studies explore its underlying molecular mechanism. In this study, we used the network pharmacology method combined with the transcriptome approach to investigate its underlying anti-inflammatory mechanism in human microglial cells. Based on network pharmacology analysis, four putative target proteins and ten potential pathways were identified. Among them, vascular endothelial growth factor A (VEGFA), epidermal growth factor receptor (EGFR) and the related phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT), the mitogen-activated protein kinase (MAPK), mechanistic target of rapamycin (mTOR) signaling pathway were well-supported by transcriptome data. Meanwhile, transcriptome analysis supplemented two crucial targets: the insulin receptor (InsR) and insulin-like growth factor-I (IGF-1) receptor. Subsequently, VEGFA, EGFR, IGF-1 receptor, and InsR were further verified on the protein level. Taken together, we assumed that tangeretin could exert protective effects on neuroinflammation by decreasing the expression of VEGFA, EGFR, InsR, and IGF-1 receptor in the PI3K-AKT, MAPK, mTOR signaling pathway. More importantly, it is for the first time to show that the anti-neuroinflammatory effects of tangeretin through VEGFA, EGFR, IGF-1 receptor, InsR, and mTOR signaling pathway. These works offer new insight into the anti-neuroinflammatory functions of tangeretin and propose novel information on further anti-inflammatory mechanism studies.

The Calcium-Dependent Protein Kinase CPK33 Mediates Strigolactone-Induced Stomatal Closure in Arabidopsis thaliana.

Strigolactones (SLs) are known to mediate plant acclimation to environmental stress. We recently reported that SLs acted as prominent regulators in promotion of stomatal closure. However, the detailed mechanism by which SLs induce stomatal closure requires further investigation. Here we studied the essential role of the calcium (Ca2+) signal mediating by the calcium-dependent protein kinase (CPK) in SL-induced stomatal closure. SL-induced stomatal closure was strongly inhibited by a Ca2+ chelator and Ca2+ channel blockers, indicating that Ca2+ functions in SL promotion of stomatal closure. Through examining a collection of cpk mutants, we identified CPK33, potentially acting as a Ca2+ transducer, which is implicated in guard cell SL signaling. SL- and Ca2+-induced stomatal closure were impaired in cpk33 mutants. CPK33 kinase activity is essential for SL induction of stomatal closure as SL-induced stomatal closure is blocked in the dead kinase mutant of CPK33. The cpk33 mutant is impaired in H2O2-induced stomatal closure, but not in SL-mediated H2O2 production. Our study thus uncovers an important player CPK33 which functions as an essential Ca2+ signals mediator in Arabidopsis guard cell SL signaling.

Strigolactones are common regulators in induction of stomatal closure in planta.

Strigolactones (SLs) have been implicated in many plant biological processes, including growth and development and the acclimation to environmental stress. We recently reported that SLs intrinsically acted as prominent regulators in induction of stomatal closure. Here we present evidence that the effect of SLs on stotamal closure is not limited to Arabidopsis, and thus SLs could serve as common regulators in the modulation of stomatal apertures of various plant species. Nevertheless, TIS108, a SL-biosynthetic inhibitor, exerted no effect on stomatal apertures. In addition, the SL receptor mutant atd14-5, similar to SL-deficient and more axillary growth 2 (max2) mutants, exhibited hypersensitivity to drought stress. Altogether, these results reinforce the role of SLs as common regulators in stress resilience.

The Multifunction of CLAVATA2 in Plant Development and Immunity.

The CLAVATA2 (CLV2) gene encodes a leucine-rich repeat receptor-like protein, a class of cell surface receptors that lacks a cytoplasmic kinase domain. As such, CLV2 is capable of functioning in concert with additional receptor(s), possibly receptor-like kinase(s), to activate cellular responses upon ligand perception. Accumulating data indicate that CLV2 is implicated in distinct biological processes including plant growth and development as well as innate immunity to microbe and nematode infections. This article focuses on recent advances in our understanding of multiple signaling pathways mediated by multifunctional CLV2 that modulate various physiological processes. The challenges and future perspectives of elucidating the specificity of CLV2-mediated signaling pathways and identifying potential co-receptors and putative ligands for CLV2 are also discussed.

Maize yield gaps caused by non-controllable, agronomic, and socioeconomic factors in a changing climate of Northeast China.

Closing the gap between current and potential yields is one means of increasing agricultural production to feed the globally increasing population. Therefore, investigation of the geographic patterns, trends and causes of crop yield gaps is essential to identifying where yields might be increased and quantifying the contributions of yield-limiting factors that may provide us potentials to enhance crop productivity. In this study, the changes in potential yields, attainable yields, potential farmers' yields, and actual farmers' yields during the past five decades in Northeast China (NEC) were investigated. Additionally the yield gaps caused by non-controllable, agronomic, and socioeconomic factors were determined. Over the period 1961 to 2010 the estimated regional area-weighted mean maize potential yield, attainable yield, and potential farmers' yield were approximately 12.3 t ha(-1), 11.5 t ha(-1), and 6.4 t ha(-1) which showed a decreasing tendency. The actual farmers' yield over NEC was 4.5 t ha(-1), and showed a tendency to increase (p<0.01) by 1.27 t ha(-1) per decade. The regional mean total yield gap (YGt), weighted by the area in each county dedicated to maize crop, was 64% of potential yield. Moreover, 8, 40, and 16% reductions in potential yields were due to non-controllable factors (YGI), agronomic factors (YGII), and socioeconomic factors (YGIII), respectively. Therefore, the exploitable yield gap, considered here as the difference between the potential yield and what one can expect considering non-controllable factors (i.e. YGt-YGI), of maize in NEC was about 56%. The regional area-weighted averages of YGt, and YGIII were found to have significant decreases of 11.0, and 10.7% per decade. At the time horizon 2010, the exploitable yield gaps were estimated to equal 36% of potential yield. This led to the conclusion that the yield gap could be deeply reduced by improving local agronomic management and controlling socioeconomic factors.

The CLE gene family in Populus trichocarpa.

The CLE (CLAVATA3/Embryo Surrounding Region-related) peptides are small secreted signaling peptides that are primarily involved in the regulation of stem cell homeostasis in different plant meristems. Particularly, the characterization of the CLE41-PXY/TDR signaling pathway has greatly advanced our understanding on the potential roles of CLE peptides in vascular development and wood formation. Nevertheless, our knowledge on this gene family in a tree species is limited. In a recent study, we reported on a systematically investigation of the CLE gene family in Populus trichocarpa. The potential roles of PtCLE genes were studied by comparative analysis and transcriptional profiling. Among fifty PtCLE members, many PtCLE proteins share identical CLE motifs or contain the same CLE motif as that of AtCLEs, while PtCLE genes exhibited either comparable or distinct expression patterns comparing to their Arabidopsis counterparts. These findings indicate the existence of both functional conservation and functional divergence between PtCLEs and their AtCLE orthologues. Our results provide valuable resources for future functional investigations of these critical signaling molecules in woody plants.

New insights into receptor-like protein functions in Arabidopsis.

Receptor-like proteins (RLPs) are implicated in plant development and immunity. Genome-wide sequence analysis identified fifty-seven RLPs in Arabidopsis. However, only a few AtRLPs have been functionally characterized. The major problems in determing the biological roles for AtRLP genes are the lack of suitable screening conditions and the high-degree of functional redundancy. In order to unravel the functions of AtRLP genes, recently we undertook a systematically functional analysis of AtRLP genes using transcriptional profiling and overexpression. Our findings indicate that most AtRLP genes are differentially expressed upon various conditions, and the expression of single AtRLP gene is often perturbed by multiple stimuli. Transgenic Arabidopsis plants overexpressing AtRLP genes were generated. Our study presents an overview of biological processes in which AtRLP genes possibly are involved, and provides a valuable resource for further investigations into the biological roles of AtRLP genes. In this article, we elaborate our findings and propose further strategies concerning the function of unknown AtRLP genes.