Analysis of plant expression profiles revealed that aphid attack triggered dynamic defense responses in sorghum plant

Sorghum [Sorghum bicolor (L.) Moench] is one of the most important cereal crops grown worldwide but is often attacked by greenbug (aphid). In response to aphid attack, host plant initiates a large transcriptional reorganization, leading to activation of the host defense genes in aphid-attacked plants. In this study, our objective was to analyze defensive responses of sorghum against aphid and identify aphid resistance genes in sorghum. For the experiments, seedlings developed from an aphid resistant germplasm line (PI 550607) were divided into two groups, then, one group was infested with greenbug ((Schizaphis graminum Rondani) and the other group was used as control (un-infested). In addition, seedlings of sorghum cultivar Tx 7000, a susceptible genotype, prepared under the same conditions, were used as a genetic control. Those plant samples were used to develop transcriptional profiles using the microarray method, from which 26.1% of the 1,761 cDNA sequences spotted on the microarray showed altered expression between two treatments at 4 days after infestation. Sequence annotation and molecular analysis revealed that many differentially expressed genes (DEGs) were related to direct host defense or signal transduction pathways, which regulate host defense. In addition to common responsive genes, unique transcripts were identified in response to greenbug infestation specifically. Later, a similar transcriptional profiling was conducted using the RNA-seq method, resulted in the identification of 2,856 DEGs in the resistant line with a comparison between infested and non-infested at 4 days and 4,354 DEGs in the resistant genotype compared to the susceptible genotype at 4 days. Based on the comparative analysis, the data of RNA-seq provided a support for the results from the microarray study as it was noticed that many of the DEGs are common in both platforms. Analysis of the two differential expression profiles indicate that aphid triggered dynamic defense responses in sorghum plants and sorghum plant defense against aphid is a complex process involving both general defense systems and specific resistance mechanisms. Finally, the results of the study provide new insights into the mechanisms underlying host plant defense against aphids and will help us design better strategies for effectively controlling aphid pest

How does destination crisis event type impact tourist emotion and forgiveness? The moderating role of destination crisis history

Drawing on attribution theory and situational crisis communication theory, this study investigates how destination crisis events impact tourist sympathy, anger, and intentions of forgiveness in four experiments. It also examines the moderating effects of destination crisis history (none vs. similar vs. dissimilar). The results of Study 1 and Study 2 revealed that external crisis events cause more sympathy and tourist forgiveness than internal ones, but less anger. They also indicated that sympathy and anger play a mediating role in destination crisis events and tourist forgiveness. The results of Study 3 and Study 4 revealed that destination crisis history predicts the impact of crisis events on tourist emotion and forgiveness. In particular, when there is no destination crisis history or similar crisis history, an external crisis event will garner more sympathy and forgiveness than an internal crisis event. These findings provide theoretical and practical implications for destination crisis management

Towards an Integrative Model of Destination Attachment: Dimensionality and Influence on Revisit Intention

Attachment is considered a universal human experience that occurs throughout the lifecycle, which provides an opportunity for both self-expression as well as connection to others. However, the greatest challenge for attachment researchers is to integrate diverse perspectives and approaches to define the construct. This study synthesized literature from relevant disciplines (i.e., psychology, marketing and human geography) to provide a comprehensive reflection upon the concept of destination attachment. A four-dimension construct of destination attachment was proposed, and its influence on revisit intention was also examined. This study provides an integrated view of the destination attachment definition, and further empirically examines the validity and reliability of the four-dimensional construct

How do tourism goal disclosure motivations drive Chinese tourists\u27 goal-directed behaviors? The influences of feedback valence, affective rumination, and emotional engagement

Based on self-determination theory and the broaden-and-build theory of positive emotion, this study investigated the motivations of disclosing tourism goals on social media and its impacts on Chinese tourists\u27 goal-directed behaviors (GDBs). We proposed and tested a mutual transformation model of tourism goal disclosure motivation under different conditions of feedback valence (positive vs. negative feedback) and examine the mediating role of tourists\u27 affective rumination and emotional engagement. The results revealed that tourists driven by extrinsic motivations develop a stronger emotional engagement in their tourism goals and exhibit more GDBs after receiving positive feedback on their disclosed tourism goals. However, negative feedback disclosed goals lowers GDBs and leads to affective rumination about tourism goals among those with intrinsic motivations. This study provides theoretical and practical implications for destination marketers to adopt marketing strategies based on the findings

Does destination nostalgic advertising enhance tourists’ intentions to visit? The moderating role of destination type

This study investigates the impact of nostalgic advertising and perceived destination types on tourists using four experiments. Study 1a and Study 1b revealed that destination nostalgic advertising is more likely to evoke tourists\u27 history sense and further trigger visit intention, while destination non-nostalgic advertising is more likely to evoke tourists\u27 fashion sense and further trigger visit intention. Study 2a and Study 2b revealed that perceived destination type plays a moderating role in these effects. Nostalgic advertising in utilitarian destinations is more likely to evoke tourists\u27 history sense and further trigger visit intentions, while non-nostalgic advertising in hedonic destinations is more likely to evoke tourists’ fashion sense and further enhance visit intentions. These findings have valuable implications for destination marketers seeking to develop effective marketing strategies

The influence of tourists\u27 monetary and temporal sunk costs on destination trust and visit intention

Although the phenomenon of sunk costs is common in tourism situations, tourism research has largely ignored its effect on tourists. Drawing on prospect theory, cognitive dissonance theory, and signal theory, this study proposed that monetary sunk cost and temporal sunk cost both have significant impact on potential tourists\u27 visit intention. Four scenario-based experiments were performed to test hypothesized relationships. Findings revealed that monetary sunk cost has a negative effect on visit intention, while temporal sunk cost has a positive effect. Good destination reputation attenuates the effects, and destination trust mediates the relationship between sunk cost and visit intention. These studies extend existing theoretical applications by identifying the conditions under which sunk cost can influence tourists\u27 visit intention, and provides relevant practical suggestions for tourism product suppliers and local government departments

How do destination negative events trigger tourists’ perceived betrayal and boycott? The moderating role of relationship quality

This study presented and tested a conceptual model that examined how a negative event at a tourism destination influenced perceived betrayal and boycott among tourists. A mixed method approach with three studies was adopted to verify the proposed hypotheses. In Study 1, using Weibo microblogging platform data, we evaluated the impacts of a negative event on tourists\u27 perception of betrayal and intentions to participate in a tourism boycott. In Study 2, an experimental study was conducted to investigate the relationships among the negative event, perceptions of betrayal, and propensity for a tourism boycott. In Study 3, an additional experimental study revealed that relationship quality would moderate the influences of negative events on perceptions of betrayal and intention to join a boycott. The findings of this study offer theoretical and managerial implications for destination management organizations’ responses to negative events

In-group favoritism or black sheep effect? The moderating role of norm strength on destination residents’ responses towards deviant behaviors

Drawing on social identity theory and focus theory of norms, this study investigated differences in how destination residents respond to deviant behaviors by other residents—members of their in-group—and similar behavior by tourists, who they see as the out-group. We proposed and tested a conceptual model of the transition between in-group favoritism and the black sheep effect under the moderating effect of norm strength. A mixed-method approach, including a secondary data study and three scenario-based experiments, was applied. Findings of this study revealed that focal residents showed in-group favoritism for other residents\u27 deviant behavior compared with tourists. The contagion effect of deviant behavior was stronger among in-groups than out-groups. However, with respect to behaviors about which norms are tight, the black sheep effect comes into play, as focal residents hold a higher desire to punish in-groups’ deviant behavior than the out-group. This study has theoretical and practical implications for destination marketing organizations

Integrated transcriptomic and pathway analyses of sorghum plants revealed the molecular mechanisms of host defense against aphids

Sugarcane aphid has emerged as a major pest of sorghum recently, and a few sorghum accessions were identified for resistance to this aphid so far. However, the molecular and genetic mechanisms underlying this resistance are still unclear. To understand these mechanisms, transcriptomics was conducted in resistant Tx2783 and susceptible BTx623 sorghum genotypes infested with sugarcane aphids. A principal component analysis revealed differences in the transcriptomic profiles of the two genotypes. The pathway analysis of the differentially expressed genes (DEGs) indicated the upregulation of a set of genes related to signal perception (nucleotide-binding, leucine-rich repeat proteins), signal transduction [mitogen-activated protein kinases signaling, salicylic acid (SA), and jasmonic acid (JA)], and plant defense (transcription factors, flavonoids, and terpenoids). The upregulation of the selected DEGs was verified by real-time quantitative PCR data analysis, performed on the resistant and susceptible genotypes. A phytohormone bioassay experiment showed a decrease in aphid population, plant mortality, and damage in the susceptible genotype when treated with JA and SA. Together, the results indicate that the set of genes, pathways, and defense compounds is involved in host plant resistance to aphids. These findings shed light on the specific role of each DEG, thus advancing our understanding of the genetic and molecular mechanisms of host plant resistance to aphids

Experimental Study of Fast Sealing Airbag in Simulating Tunnel

AbstractAgainst problems in terms of stability, airtightness and so on of current fast sealing airbag, stability and airtightness of fast sealing airbag in simulating tunnel was studied through combining theoretical analysis and experiment. The ideal viton material is finally found after comparing and analyzing heat resistance, flame resistance, wear resistance, hardness and air permeability of different kinds of rubber. Sealing and wind blocking effects of airbags made from selected material are tested in simulating tunnel. Rate of air leakage and changing rate of wind pressure of each kind of rubber are also determined and further verified, with result that both indexes of viton material are the least, respectively only 4.25% and 4.66%