Differential expression patterns among heat-shock protein genes and thermal responses in the whitefly Bemisia tabaci (MEAM 1)

The Transcriptional Landscape of Adaptive Thermal Plasticity Within and Across Generations: The Role of Gene Expression and Alternative Splicing

There is increasing evidence for the co-occurrence of adaptive within-generation (WGP) and transgenerational (TGP) plasticity and the ecological scenarios driving both types of plasticity. However, some aspects of their transcriptional mechanisms, such as the role of alternative splicing and the consequences of parental acclimation across life stages, have remained elusive. We explore these fundamental questions by considering the desert endemic Drosophila mojavensis for which prior evidence indicates adaptive thermal acclimation within and across generations. We implement a full factorial design to estimate genome-wide patterns of differential gene expression (DE) and alternative splicing (AS) in response to acclimation treatments performed in the parental and offspring generations, as well as considering larval and adult stages. Our results demonstrate that mechanisms of alternative splicing represent a substantial difference between WGP and TGP. These mechanisms contribute substantially to transcriptional plasticity within generations but not across generations. We found a great number of genes associated with transcriptional TGP, which is exclusive to larval stages and not adult samples. Finally, we provide evidence demonstrating opposing transcriptional trajectories in differential gene expression between WGP and TGP. Thus, parental acclimation appears to up-regulate genes that are down-regulated during offspring acclimation. This pattern suggests a possible hypothesis for the mechanisms explaining the compensatory effect of parental acclimation in the offspring generation.

Heat-shock protein 70-a hub gene-underwent adaptive evolution involved in whitefly-wild tomato interaction

BACKGROUND

The whitefly Bemisia tabaci causes severe damage to cultivated tomato plants, but actively avoids the wild tomato Solanum habrochaites. Moreover, the mortality of whitefly increases significantly after feeding with the wild tomato. However, additional experiments are warranted to more carefully elucidate the specific molecular elements underlying the interaction between whitefly and wild tomato.

RESULTS

Our results showed that S. habrochaites significantly increases the mortality of whitefly adults and decreases both their fertility and fecundity. In addition, the expression of stress-response genes in whitefly after exposure to S. habrochaites was analyzed using RNA sequencing. Weighted gene co-expression network analysis was conducted to identify the hub genes to determine their potential associations with the mortality of whitefly. These results suggested that the expression of heat-shock protein (HSP), multicopper oxidase, and 2-Oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (OHCU) decarboxylase genes were induced in whitefly. To validate the gene associations with whitefly mortality, a high-throughput in vivo model system and RNAi-based gene silencing were used. The results revealed that the RNAi-mediated depletion of the HSP gene, which belongs to the HSP70 subfamily, increased the mortality of whitefly. Furthermore, the selection pressure analysis showed that a total of five amino acid sites of positive selection were identified, three of which were located in the nucleotide-binding domain and the other two in the substrate-binding domain.

CONCLUSIONS

This is the first report on the potential implication of HSPs in whitefly-wild plant interactions. This study could more precisely identify the molecular mechanisms of whitefly in response to wild tomatoes. © 2022 Society of Chemical Industry.

Genome-Wide Identification and Analysis of the Heat-Shock Protein Gene Superfamily in Bemisia tabaci and Expression Pattern Analysis under Heat Shock

Simple Summary

Bemisia tabaci MED is an invasive pest that had caused considerable economic damage in the past decades. Its successful colonization is closely related to heat-shock proteins (HSPs), which are related to heat resistance. In this study, 33 BtaHsps were identified based on the sequenced genome of B. tabaci MED belonging to six HSP families, among which 22 BtaHsps were newly identified. Analysis of the secondary structure and evolutionary relationship showed that they were all closely related. In addition, BtaHsp90A3 of the HSP90 family was screened by analyzing the expression level changes of these genes under 42 °C heat shock and RNAi was performed on the BtaHsp90A3. The results showed that the silencing of BtaHsp90A3 is closely related to the heat resistance of B. tabaci MED. Taken together, this study conducted an in-depth identification of BtaHsps that clarifies their evolutionary relationships and their response to thermal stress in B. tabaci MED.

Abstract

The thermal tolerance of Bemisia tabaci MED, an invasive whitefly species with worldwide distribution, plays an important role in its ecological adaptation during the invasion process. Heat-shock proteins (HSPs) are closely related to heat resistance. In this study, 33 Hsps (BtaHsps) were identified based on sequenced genome of B. tabaci MED belonging to six HSP families, among which 22 Hsps were newly identified. The secondary structures of a further 22 BtaHsps were also predicted. The results of RT-qPCR showed that heat shock could affect the expression of 14 of the 22 Hsps newly identified in this study. Among them, the expression level of six Hsps increased under 42 °C treatment. As the unstudied gene, BtaHsp90A3 had the highest increase rate. Therefore, BtaHsp90A3 was chosen for the RNAi test, and silencing BtaHsp90A3 by RNAi decreased the survival rate of adult B. tabaci at 42 °C. The results indicated that only a few Hsps were involved in the thermal tolerance of host whitefly although many Hsps would response under heat stress. This study conducted a more in-depth and comprehensive identification that demonstrates the evolutionary relationship of BtaHsps and illustrates the response of BtaHsps under the influence of thermal stress in B. tabaci MED.

Developing extreme heat acclimation in Bemisia tabaci Mediterranean (Hemiptera: Aleyrodidae)

Bemisia tabaci Mediterranean (MED) is a highly invasive cryptic species complex found in the world's tropical, subtropical, and temperate regions. It is a severe pest of various crops and a vector of plant pathogenic viruses, particularly geminiviruses. Thermal acclimation of insects is a critical for the survival in unfavorable temperature condition. We observed that great survival rate of B. tabaci MED at the uncontrolled greenhouse which had fluctuating temperature condition (FTC) from 10°C to 60°C in spring and summer season. Our study showed that while B. tabaci MED reared under FTC for 10 weeks from April to June, its survival rate was gradually increased when heat shock was treated 50°C for 0.5 h. In contrast, the same heat shock treatment was lethal in the colony reared under constant temperature condition (CTC) at the controlled insectary. After being acclimated, the lethal temperatures LT₅₀ , LT₉₅ , and LT₁₀₀ under CTC were 47.7°C, 50.1°C, and 50.3°C, whereas those under FTC were 59.8°C, 62.7°C, and 63.0°C, respectively. In addition, we observed that the transcript levels of three investigated heat shock protein (HSP) genes (hsp20, hsp70, and hsp90) were lower under FTC than under CTC. This study suggests that B. tabaci MED retains high heat acclimation ability, making it tolerant of extreme thermal conditions.

Hsian-Tsao (Mesona chinensis Benth.) Extract Improves the Thermal Tolerance of Drosophila melanogaster

Global warming has prompted scientific communities to consider how to alleviate thermal stress in humans and animals. The present study assessed the supplementation of hsian-tsao extract (HTE) on thermal stress in Drosophila melanogaster and preliminarily explicated its possible physiological and molecular mechanisms. Our results indicated that the lethal time for 50% of female flies fed on HTE was significantly longer than that of male flies at the same heat stress temperature. Under thermal stress, the survival time of females was remarkably increased in the HTE addition groups compared to the non-addition group. Thermal hardening by acute exposure to 36°C for 30 min (9:00 to 9:30 a.m.) every day could significantly prolong the longevity of females. Without thermal hardening, HTE increased the antioxidant capacity of females under heat stress, accompanied by an increment of catalase (CAT) activity, and the inhibition for hydroxyl radicals (OH⋅) and superoxide anions (⋅O2 -). Superoxide dismutase (SOD) activity and the inhibition for ⋅O2 - was significantly affected by thermal hardening in the non-HTE addition groups, and significant differences were shown in CAT and SOD activities, and the inhibition for ⋅O2 - among groups with thermal hardening. After heat exposure, heat shock protein 70 (Hsp70) was only up-regulated in the group with high levels of added HTE compared with the group without and this was similar in the thermal hardening group. It was concluded that the heat stress-relieving ability of HTE might be partly due to the enhancement of enzymatic activities of SOD and CAT, and the inhibition for OH⋅ and ⋅O2 -. However, the expression levels of Hsp70 were not well related to thermal tolerance or heat survival.

Genomic knockout of hsp23 both decreases and increases fitness under opposing thermal extremes in Drosophila melanogaster

Under exposure to harmful environmental stresses, organisms exhibit a general stress response involving upregulation of the expression of heat shock proteins (HSPs) which is thought to be adaptive. Small heat shock proteins (sHSPs) are key components of this response, although shsp genes may have other essential roles in development. However, the upregulation of expression of a suite of genes under stress may not necessarily be evidence of an adaptive response to stress that involves those genes. To explore this issue, we used the CRISPR/Cas9 system to investigate pleiotropic effects of the hsp23 gene in Drosophila melanogaster. Transgenic flies carrying a pCFD5 plasmid containing sgRNAs were created to generate a complete knockout of the hsp23 gene. The transgenic line lacking hsp23 showed an increased hatch rate and no major fitness costs under an intermediate temperature used for culturing the flies. In addition, hsp23 knockout affected tolerance to hot and cold temperature extremes but in opposing directions; knockout flies had reduced tolerance to cold, but increased tolerance to heat. Despite this, hsp23 expression (in wild type flies) was increased under both hot and cold conditions. The hsp23 gene was required for heat hardening at the pupal stage, but not at the 1st-instar larval stage, even though the gene was upregulated in wild type controls at that life stage. The phenotypic effects of hsp23 were not compensated for by expression changes in other shsps. Our study shows that the fitness consequences of an hsp gene knockout depends on environmental conditions, with potential fitness benefits of gene loss even under conditions when the gene is normally upregulated.

Effects of di-(2-ethylhexyl) phthalate on Transcriptional Expression of Cellular Protection-Related HSP60 and HSP67B2 Genes in the Mud Crab Macrophthalmus japonicus

Di-2-ethylhexyl phthalate (DEHP) has attracted attention as an emerging dominant phthalate contaminant in marine sediments. Macrophthalmus japonicus, an intertidal mud crab, is capable of tolerating variations in water temperature and sudden exposure to toxic substances. To evaluate the potential effects of DEHP toxicity on cellular protection, we characterized the partial open reading frames of the stress-related heat shock protein 60 (HSP60) and small heat shock protein 67B2 (HSP67B2) genes of M. japonicus and further investigated the molecular effects on their expression levels after exposure to DEHP. Putative HSP60 and small HSP67B2 proteins had conserved HSP-family protein sequences with different C-terminus motifs. Phylogenetic analysis indicated that M. japonicus HSP60 (Mj-HSP60) and M. Japonicus HSP67B2 (Mj-HSP67B2) clustered closely with Eriocheir sinensis HSP60 and Penaeus vannamei HSP67B2, respectively. The tissue distribution of Heat shock proteins (HSPs) was the highest in the gonad for Mj-HSP60 and in the hepatopancreas for Mj-HSP67B2. The expression of Mj-HSP60 Messenger Ribonucleic Acid (mRNA) increased significantly at day 1 after exposure to all doses of DEHP, and then decreased in a dose-dependent and exposure time-dependent manner in the gills and hepatopancreas. Mj-HSP67B2 transcripts were significantly upregulated in both tissues at all doses of DEHP and at all exposure times. These results suggest that cellular immune protection could be disrupted by DEHP toxicity through transcriptional changes to HSPs in crustaceans. Small and large HSPs might be differentially involved in responses against environmental stressors and in detoxification in M. japonicus crabs.

Uninterrupted Development of Two Aphid Species Belonging to Cinara Genus during Winter Diapause

Aphids are herbivores carrying the status of major pests for crops and ornamental plants. The many specific biological features of aphids allow them to survive unfavorable environmental conditions. As for other insects, a predominant strategy for aphids surviving winter, is laying diapausing eggs. During diapause, the expression of development may vary between species. Most of the insects stop growing during diapause; however, there is limited information about this process. We immunostained the embryos of aphids in order to detect cell division during diapause. Here, for the first time, we present that two species of aphids belonging to Cinara grow and develop throughout the duration of the winter diapause. Our results showed that the “resting stage” does not occur in embryos of these aphid species. The embryo of C. cupressi and C. juniperi undergoes a type of diapause, with slow growth. It seems that this feature is conducive to the rapid development of embryos in the egg, which may be another specific feature for aphid biology of overwintering.

Molecular characterization of eight ATP-dependent heat shock protein transcripts and their expression profiles in response to stresses in the spruce budworm, Choristoneura fumiferana (L.)

Heat shock proteins (HSPs) greatly contribute to insect stress tolerance and enhance survival and adaptation in severe environmental conditions. To investigate the potential roles of HSPs in the spruce budworm, Choristoneura fumiferana (L.), an important native pest of forests in North America, we found eight ATP-dependent HSP transcripts (CfHSPs). Based on molecular characteristics, the identified HSP genes were classified into HSP70 and HSP90 families, and phylogenetic results showed that they had orthologues in other insects. The transcript levels of these HSPs were measured using RT-qPCR under normal and stressful conditions in the laboratory. Under normal conditions, three HSP genes were consistently expressed in all life stages, whereas expression of the other five genes was dependent on the developmental stage. In the larvae, most CfHSP transcripts displayed similar expression levels among different tissues. Under heat shock conditions, one HSP70 gene and one HSP90 gene were upregulated in all life stages. One HSP70 gene was upregulated after cold injury in the larval stage. With starvation, HSP gene expression exhibited complex expression patterns; most of them were downregulated. These results suggest that the ATP-dependent HSPs have multiple roles during normal development as well as under stressful conditions including heat, cold injury and starvation.

Effects of Simulated Heat Waves on Life History Traits of a Host Feeding Parasitoid

The frequency and amplitude of heat waves are predicted to increase under future climate change conditions. We still lack a detailed understanding of how changes in the frequency and amplitude of heat waves are linked to the life history traits and biocontrol efficiency of host-feeding parasitoids. In the present study, we simulated a series of heat waves as a function of amplitude and frequency to investigate the effects on the life history traits of the host-feeding parasitoid Eretmocerus hayati. We found that both the amplitude and frequency of heat waves significantly affected the adult phenotypes. In the low-amplitude heat wave group, the frequency of heat waves did not change the life history traits of the parasitoid; however, when the heat amplitude reached 42 °C, medium (four times/week) and high frequencies (seven times/week) of heat waves detrimentally affected these parameters. Hence, these findings suggest that to obtain optimal biological control with this parasitoid, we need to carefully monitor heat wave pattern (especially the amplitude and frequency) over the short term (usually 7-10 days) before releasing a host-feeding parasitoid.

Microevolution or wide tolerance? Level of stress proteins in the beet armyworm Spodoptera eqigua hübner (Lepidoptera: Noctuidae) exposed to cadmium for over 150 generations

The aim of this study was to investigate whether the cadmium tolerance developed in the beet armyworm Spodoptera exigua selected for over 150 generations may be related to synthesis of the stress proteins metallothioneins (Mts) and 70 kDa heat shock proteins (HSP70). To achieve this, six S. exigua strains (control, k), 150-generation Cd exposure strain (cd), and four 18-generation Cd exposure strains differing in Cd concentration (cd44, cd22, cd11, cd5) were reared. Stress protein level was measured in the midgut of the 5th larval stage after 1-6, 12 and 18 generations. Cd contents was measured in the pupae. Unlike Cd concentration, which depended on metal contents in food but was not generation-dependent, the pattern of Mts and HSP70 concentrations changed in experimental strains from generation to generation. Stress protein levels in the insects exposed to the highest Cd concentration (the same as in the 150-generation Cd exposure strain), initially higher than in the control strain, after the 12th generation did not differ from the level measured in the control strains. It seems therefore that stress proteins play a protective role in insects of lower tolerance to cadmium. The tolerance developed during multigenerational exposure probably relies on mechanisms other than Mt and HSP70 synthesis.

Characterization of genes encoding small heat shock proteins from Bemisia tabaci and expression under thermal stress

Small heat shock proteins (sHSPs) are probably the most diverse in structure and function among the various super-families of stress proteins, and they play essential roles in various biological processes. The sweet potato whitefly, Bemisia tabaci (Gennadius), feeds in the phloem, transmits several plant viruses, and is an important pest on cotton, vegetables and ornamentals. In this research, we isolated and characterized three α-crystallin/sHSP family genes (Bthsp19.5, Bthsp19.2, and Bthsp21.3) from Bemisia tabaci. The three cDNAs encoded proteins of 171, 169, and 189 amino acids with calculated molecular weights of 19.5, 19.2, and 21.3 kDa and isoelectric points of 6.1, 6.2, and 6.0, respectively. The deduced amino acid sequences of the three genes showed strong similarity to sHSPs identified in Hemiptera and Thysanoptera insects species. All three sHSPs genes from Bemisia tabaci lacked introns. Quantitative real-time PCR analyses revealed that the three BtsHSPs genes were significantly up-regulated in Bemisia tabaci adults and pupae during high temperature stress (39, 41, 43, and 45 °C) but not in response to cold temperature stress (-6, -8, -10, and -12 °C). The expression levels of Bthsp19.2 and Bthsp21.3 in pupae was higher than adults in response to heat stress, while the expression level of Bthsp19.5 in adults was higher than pupae. In conclusion, this research results show that the sHSP genes of Bemisia tabaci had shown differential expression changes under thermal stress.

A transcriptional and functional analysis of heat hardening in two invasive fruit fly species, Bactrocera dorsalis and Bactrocera correcta

Many insects have the capacity to increase their resistance to high temperatures by undergoing heat hardening at nonlethal temperatures. Although this response is well established, its molecular underpinnings have only been investigated in a few species where it seems to relate at least partly to the expression of heat shock protein (Hsp) genes. Here, we studied the mechanism of hardening and associated transcription responses in larvae of two invasive fruit fly species in China, Bactrocera dorsalis and Bactrocera correcta. Both species showed hardening which increased resistance to 45°C, although the more widespread B. dorsalis hardened better at higher temperatures compared to B. correcta which hardened better at lower temperatures. Transcriptional analyses highlighted expression changes in a number of genes representing different biochemical pathways, but these changes and pathways were inconsistent between the two species. Overall B. dorsalis showed expression changes in more genes than B. correcta. Hsp genes tended to be upregulated at a hardening temperature of 38°C in both species, while at 35°C many Hsp genes tended to be upregulated in B. correcta but not B. dorsalis. One candidate gene (the small heat shock protein gene, Hsp23) with a particularly high level of upregulation was investigated functionally using RNA interference (RNAi). We found that RNAi may be more efficient in B. dorsalis, in which suppression of the expression of this gene removed the hardening response, whereas in B. correcta RNAi did not decrease the hardening response. The different patterns of gene expression in these two species at the two hardening temperatures highlight the diverse mechanisms underlying hardening even in closely related species. These results may provide target genes for future control efforts against such pest species.

Multigenerational heat acclimation increases thermal tolerance and expression levels of Hsp70 and Hsp90 in the rice leaf folder larvae

Physiological response and acclimation to thermal stress is a key strategy of insects to cope with changing climate. The underlying mechanism of heat acclimation in insects is still unclear. Here, the heat selection and transcript level response in the larvae of the rice leaf folder Cnaphalocrocis medinalis Güenée, a serious pest of rice in summer, were studied. The survival and fecundity of larvae during multigenerational heat selection at 39 °C were examined, and heat tolerance and mRNA expression of heat shock protein 70 (Hsp70) and 90 (Hsp90) were examined under heat stress. The results showed that survival and fecundity of larvae increased notably and then kept constant after two or three generations of heat selection. Heat selection improved thermal tolerance of larvae. The Hsp70 mRNA expression of the 3rd-instar larvae increased in all five generations of heat selection, but Hsp90 increased only in the first two generations. The response of Hsp70 to 39 °C heat treatment in the larvae kept at 27 °C was different from the larvae exposed to the conditioning heat treatments, but the response of Hsp 90 was similar. Moreover, the Hsp70 and Hsp90 mRNA expression levels were significantly higher in the heat-acclimated larvae than that in the unacclimated larvae at a comparable duration of exposure to 37 and 41 °C. Selection at a high temperature across multiple generations led larvae to heat acclimation, and Hsp70 and Hsp90 were involved in this acclimation process.

Comparative transcriptome analysis reveals differentially expressed genes in the Asian citrus psyllid (Diaphorina citri) upon heat shock

Temperature is an important factor influencing insect distribution. In the tropical and subtropical regions, insects always suffer the extreme temperature. Therefore, appropriate molecular response to temperature change is crucial for their survival. To understand how Diaphorina citri responds to high temperature at the molecular level, we conducted a comparative analysis of the transcriptomes of D. citri under room temperature and 40 °C heat shock treatment. The RNA sequencing analysis identified a total of 451 differentially expressed genes upon heat stress, including 167 down-regulated genes and 284 up-regulated genes. Thermal stress mainly significantly induced the transcription of molecular chaperone, protein biosynthesis and oxidation resistance, including members of the heat shock protein families, ATPases, and detoxifying enzymes. This study provides a preliminary insight into the transcriptional response of D. citri to heat stress and provides a foundation for the future functional validation of genes involved in thermotolerance in this important insect pest in tropical and subtropical regions.

Genome-wide identification and characterization of HSP gene superfamily in whitefly (Bemisia tabaci) and expression profiling analysis under temperature stress

Heat shock proteins (HSP) are essential molecular chaperones that play important roles in the stress stimulation of insects. Bemisia tabaci, a phloem feeder and invasive species, can cause extensive crop damage through direct feeding and transmission of plant viruses. Here we employed comprehensive genomics approaches to identity HSP superfamily members in the Middle East Asia Minor 1 whitefly genome. In total, we identified 26 Hsp genes, including three Hsp90, 17 Hsp70, one Hsp60 and five sHSP (small heat shock protein) genes. The HSP gene superfamily of whitefly is expanded compared with the other five insects surveyed here. The gene structures among the same families are relatively conserved. Meanwhile, the motif compositions and secondary structures of BtHsp proteins were predicted. In addition, quantitative polymerase chain reaction analysis showed that the expression patterns of BtHsp gene superfamily were diverse across different tissues of whiteflies. Most Hsp genes were induced or repressed by thermal stress (40°C) and cold treatment (4°C) in whitefly. Silencing the expression of BtHsp70-6 significantly decreased the survival rate of whitefly under 45°C. All the results showed the Hsps conferred thermo-tolerance or cold-tolerance to whiteflies that protect them from being affected by detrimental temperature conditions. Our observations highlighted the molecular evolutionary properties and the response mechanism to temperature assaults of Hsp genes in whitefly.

Quantitative Proteomic Analysis Provides Insights into Rice Defense Mechanisms against Magnaporthe oryzae

Blast disease is one of the major rice diseases, and causes nearly 30% annual yield loss worldwide. Resistance genes that have been cloned, however, are effective only against specific strains. In cultivation practice, broad-spectrum resistance to various strains is highly valuable, and requires researchers to investigate the basal defense responses that are effective for diverse types of pathogens. In this study, we took a quantitative proteomic approach and identified 634 rice proteins responsive to infections by both Magnaporthe oryzae strains Guy11 and JS153. These two strains have distinct pathogenesis mechanisms. Therefore, the common responding proteins represent conserved basal defense to a broad spectrum of blast pathogens. Gene ontology analysis indicates that the “responding to stimulus” biological process is explicitly enriched, among which the proteins responding to oxidative stress and biotic stress are the most prominent. These analyses led to the discoveries of OsPRX59 and OsPRX62 that are robust callose inducers, and OsHSP81 that is capable of inducing both ROS production and callose deposition. The identified rice proteins and biological processes may represent a conserved rice innate immune machinery that is of great value for breeding broad-spectrum resistant rice in the future.

Thermotolerance and Heat-Shock Protein Gene Expression Patterns in Bemisia tabaci (Hemiptera: Aleyrodidae) Mediterranean in Relation to Developmental Stage

Temperature plays an important role in the growth, development, and geographic distribution of insects. There is convincing evidence that heat-shock proteins (HSPs) play important roles in helping organisms adapt to thermal stress. To better understand the physiological and ecological influence of thermal stress on the different development stages of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Mediterranean species (MED), nymphs and adults were shocked with temperatures of 35, 38, and 41℃ for 1 and 2 h, respectively, and the survival rate, fecundity, and developmental duration were investigated in the laboratory. The expression levels of the hsp40, hsp70, and hsp90 genes were assessed using real-time PCR. The results indicate that the survival rates of the nymphs and adults decreased with increased temperature. A 2-h heat shock at 41℃ induced a significant reduction in fecundity in adults and an increase in developmental duration in young nymphs. Hsp90 showed higher temperature responses to thermal stress than hsp40 or hsp70. The expression levels of the hsps in the adults were significantly down-regulated by a 2-h heat shock at 41℃ compared with that by a 1-h treatment. A significant decrease in the expression levels of the hsps also occurred in the adults when the temperature increased from 38 to 41℃ for the 2-h treatment, whereas no significant decrease occurred in the nymphs. Compared with previous studies, we provide some evidence indicating that MED has the potential to adapt to a wider temperature range than the Middle East-Asia Minor 1 species.

De novo characterization of the pine aphid Cinara pinitabulaeformis Zhang et Zhang transcriptome and analysis of genes relevant to pesticides

The pine aphid Cinara pinitabulaeformis Zhang et Zhang is the main pine pest in China, it causes pine needles to produce dense dew (honeydew) which can lead to sooty mold (black filamentous saprophytic ascomycetes). Although common chemical and physical strategies are used to prevent the disease caused by C. pinitabulaeformis Zhang et Zhang, new strategies based on biological and/or genetic approaches are promising to control and eradicate the disease. However, there is no information about genomics, proteomics or transcriptomics to allow the design of new control strategies for this pine aphid. We used next generation sequencing technology to sequence the transcriptome of C. pinitabulaeformis Zhang et Zhang and built a transcriptome database. We identified 80,259 unigenes assigned for Gene Ontology (GO) terms and information for a total of 11,609 classified unigenes was obtained in the Clusters of Orthologous Groups (COGs). A total of 10,806 annotated unigenes were analyzed to identify the represented biological pathways, among them 8,845 unigenes matched with 228 KEGG pathways. In addition, our data describe propagative viruses, nutrition-related genes, detoxification related molecules, olfactory related receptors, stressed-related protein, putative insecticide resistance genes and possible insecticide targets. Moreover, this study provides valuable information about putative insecticide resistance related genes and for the design of new genetic/biological based strategies to manage and control C. pinitabulaeformis Zhang et Zhang populations.

The Involvement of Heat Shock Proteins in the Establishment of Tomato Yellow Leaf Curl Virus Infection

Tomato yellow leaf curl virus (TYLCV), a begomovirus, induces protein aggregation in infected tomatoes and in its whitefly vector Bemisia tabaci. The interactions between TYLCV and HSP70 and HSP90 in plants and vectors are necessity for virus infection to proceed. In infected host cells, HSP70 and HSP90 are redistributed from a soluble to an aggregated state. These aggregates contain, together with viral DNA/proteins and virions, HSPs and components of the protein quality control system such as ubiquitin, 26S proteasome subunits, and the autophagy protein ATG8. TYLCV CP can form complexes with HSPs in tomato and whitefly. Nonetheless, HSP70 and HSP90 play different roles in the viral cell cycle in the plant host. In the infected host cell, HSP70, but not HSP90, participates in the translocation of CP from the cytoplasm into the nucleus. Viral amounts decrease when HSP70 is inhibited, but increase when HSP90 is downregulated. In the whitefly vector, HSP70 impairs the circulative transmission of TYLCV; its inhibition increases transmission. Hence, the efficiency of virus acquisition by whiteflies depends on the functionality of both plant chaperones and their cross-talk with other protein mechanisms controlling virus-induced aggregation.

The potential of using biotechnology to improve cassava: a review

The importance of cassava as the fourth largest source of calories in the world requires that contributions of biotechnology to improving this crop, advances and current challenges, be periodically reviewed. Plant biotechnology offers a wide range of opportunities that can help cassava become a better crop for a constantly changing world. We therefore review the state of knowledge on the current use of biotechnology applied to cassava cultivars and its implications for breeding the crop into the future. The history of the development of the first transgenic cassava plant serves as the basis to explore molecular aspects of somatic embryogenesis and friable embryogenic callus production. We analyze complex plant-pathogen interactions to profit from such knowledge to help cassava fight bacterial diseases and look at candidate genes possibly involved in resistance to viruses and whiteflies-the two most important traits of cassava. The review also covers the analyses of main achievements in transgenic-mediated nutritional improvement and mass production of healthy plants by tissue culture and synthetic seeds. Finally, the perspectives of using genome editing and the challenges associated to climate change for further improving the crop are discussed. During the last 30 yr, great advances have been made in cassava using biotechnology, but they need to scale out of the proof of concept to the fields of cassava growers.

Identification, genomic organization and expression profiles of four heat shock protein genes in the western flower thrips, Frankliniella occidentalis

The western flower thrips, Frankliniella occidentalis, is an important invasive pest with a strong tolerance for extreme temperatures; however, the molecular mechanisms that regulate thermotolerance in this insect remain unclear. In this study, four heat shock protein genes were cloned from F. occidentalis and named Fohsp90, Fohsc701, Fohsc702 and Fohsp60. These four Hsps exhibited typical characteristics of heat shock proteins. Subcellular localization signals and phylogenetic analysis indicated that FoHsp90 and FoHsc701 localize to the cytosol, whereas FoHsc702 and FoHsp60 were located in the endoplasmic reticulum and mitochondria, respectively. Analysis of genomic sequences revealed the presence of introns in the four genes (three, four, seven, and five introns for Fohsp90, Fohsc701, Fohsc702 and Fohsp60, respectively). Both the number and position of introns in these four genes were quite different from analogous genes in other species. qRT-PCR indicated that the four Fohsps were detected in second-stage larvae, one-day-old pupae, and one-day-old adults, and mRNA expression levels were lowest in larvae and highest in pupae. Fohsc701 and Fohsc702 possessed similar expression patterns and were not induced by cold or heat stress. Expression of Fohsp60 was significantly elevated by heat, and Fohsp90 was rapidly up-regulated after exposure to both cold and heat stress. Exposure to -8°C had no effect on expression of the four Fohsps; however, expression of Fohsp90 and Fohsp60 was highest after a 2-h incubation at 39°C. Furthermore, cold and heat hardening led to significant up-regulation of the four Fohsps compared to their respective controls. Collectively, our results indicate that the four FoHsps contribute to insect development and also function in rapid cold or heat hardening; furthermore, FoHsp90 and FoHsp60 contribute to thermotolerance in F. occidentalis.