Confirmation and refutation of very luminous galaxies in the early Universe.

During the first 500 million years of cosmic history, the first stars and galaxies formed, seeding the Universe with heavy elements and eventually reionizing the intergalactic medium1-3. Observations with the James Webb Space Telescope (JWST) have uncovered a surprisingly high abundance of candidates for early star-forming galaxies, with distances (redshifts, z), estimated from multiband photometry, as large as z ≈ 16, far beyond pre-JWST limits4-9. Although such photometric redshifts are generally robust, they can suffer from degeneracies and occasionally catastrophic errors. Spectroscopic measurements are required to validate these sources and to reliably quantify physical properties that can constrain galaxy formation models and cosmology10. Here we present JWST spectroscopy that confirms redshifts for two very luminous galaxies with z > 11, and also demonstrates that another candidate with suggested z ≈ 16 instead has z = 4.9, with an unusual combination of nebular line emission and dust reddening that mimics the colours expected for much more distant objects. These results reinforce evidence for the early, rapid formation of remarkably luminous galaxies while also highlighting the necessity of spectroscopic verification. The large abundance of bright, early galaxies may indicate shortcomings in current galaxy formation models or deviations from physical properties (such as the stellar initial mass function) that are generally believed to hold at later times.

Solar UV-B radiation and ethylene play a key role in modulating effective defenses against Anticarsia gemmatalis larvae in field-grown soybean.

Solar UV-B radiation has been reported to enhance plant defenses against herbivore insects in many species. However, the mechanism and traits involved in the UV-B mediated increment of plant resistance are unknown in crops species, such as soybean. Here, we studied defense-related responses in undamaged and Anticarsia gemmatalis larvae-damaged leaves of two soybean cultivars grown under attenuated or full solar UV-B radiation. We determined changes in jasmonates, ethylene (ET), salicylic acid, trypsin protease inhibitor activity, flavonoids, and mRNA expression of genes related with defenses. ET emission induced by Anticarsia gemmatalis damage was synergistically increased in plants grown under solar UV-B radiation and was positively correlated with malonyl genistin concentration, trypsin proteinase inhibitor activity and expression of IFS2, and the pathogenesis protein PR2, while was negatively correlated with leaf consumption. The precursor of ET, aminocyclopropane-carboxylic acid, applied exogenously to soybean was sufficient to strongly induce leaf isoflavonoids. Our results showed that in field-grown soybean isoflavonoids were regulated by both herbivory and solar UV-B inducible ET, whereas flavonols were regulated by solar UV-B radiation only and not by herbivory or ET. Our study suggests that, although ET can modulate UV-B-mediated priming of inducible plant defenses, some plant defenses, such as isoflavonoids, are regulated by ET alone.

Herbivore perception decreases photosynthetic carbon assimilation and reduces stomatal conductance by engaging 12-oxo-phytodienoic acid, mitogen-activated protein kinase 4 and cytokinin perception.

Herbivory-induced changes in photosynthesis have been documented in many plant species; however, the complexity of photosynthetic regulation and analysis has thwarted progress in understanding the mechanism involved, particularly those elicited by herbivore-specific elicitors. Here, we analysed the early photosynthetic gas exchange responses in Nicotiana attenuata plants after wounding and elicitation with Manduca sexta oral secretions and the pathways regulating these responses. Elicitation with M. sexta oral secretions rapidly decreased photosynthetic carbon assimilation (AC ) in treated and systemic (untreated, vascularly connected) leaves, which were associated with changes in stomatal conductance, rather than with changes in Rubisco activity and 1-5 ribulose-1,5-bisphosphate turnover. Phytohormone profiling and gas exchange analysis of oral secretion-elicited transgenic plants altered in phytohormone regulation, biosynthesis and perception, combined with micrografting techniques, revealed that the local photosynthetic responses were mediated by 12-oxo-phytodienoic acid, while the systemic responses involved interactions among jasmonates, cytokinins and abscisic acid signalling mediated by mitogen-activated protein kinase 4. The analysis also revealed a role for cytokinins interacting with mitogen-activated protein kinase 4 in CO2 -mediated stomatal regulation. Hence, oral secretions, while eliciting jasmonic acid-mediated defence responses, also elicit 12-oxo-phytodienoic acid-mediated changes in stomatal conductance and AC , an observation illustrating the complexity and economy of the signalling that regulates defence and carbon assimilation pathways in response to herbivore attack.

Gut bacteria facilitate adaptation to crop rotation in the western corn rootworm.

Insects are constantly adapting to human-driven landscape changes; however, the roles of their gut microbiota in these processes remain largely unknown. The western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) (Coleoptera: Chrysomelidae) is a major corn pest that has been controlled via annual rotation between corn (Zea mays) and nonhost soybean (Glycine max) in the United States. This practice selected for a "rotation-resistant" variant (RR-WCR) with reduced ovipositional fidelity to cornfields. When in soybean fields, RR-WCRs also exhibit an elevated tolerance of antiherbivory defenses (i.e., cysteine protease inhibitors) expressed in soybean foliage. Here we show that gut bacterial microbiota is an important factor facilitating this corn specialist's (WCR's) physiological adaptation to brief soybean herbivory. Comparisons of gut microbiota between RR- and wild-type WCR (WT-WCR) revealed concomitant shifts in bacterial community structure with host adaptation to soybean diets. Antibiotic suppression of gut bacteria significantly reduced RR-WCR tolerance of soybean herbivory to the level of WT-WCR, whereas WT-WCR were unaffected. Our findings demonstrate that gut bacteria help to facilitate rapid adaptation of insects in managed ecosystems.

Soybean resistance to stink bugs (Nezara viridula and Piezodorus guildinii) increases with exposure to solar UV-B radiation and correlates with isoflavonoid content in pods under field conditions.

Solar UV-B radiation (280-315 nm) has a significant influence on trophic relationships in natural and managed ecosystems, affecting plant-insect interactions. We explored the effects of ambient UV-B radiation on the levels of herbivory by stink bugs (Nezara viridula and Piezodorus guildinii) in field-grown soybean crops. The experiments included two levels of UV-B radiation (ambient and attenuated UV-B) and four soybean cultivars known to differ in their content of soluble leaf phenolics. Ambient UV-B radiation increased the accumulation of the isoflavonoids daidzin and genistin in the pods of all cultivars. Soybean crops grown under attenuated UV-B had higher numbers of unfilled pods and damaged seeds than crops grown under ambient UV-B radiation. Binary choice experiments with soybean branches demonstrated that stink bugs preferred branches of the attenuated UV-B treatment. We found a positive correlation between percentage of undamaged seeds and the contents of daidzin and genistin in pods. Our results suggest that constitutive and UV-B-induced isoflavonoids increase plant resistance to stink bugs under field conditions.

Both Volatiles and Cuticular Plant Compounds Determine Oviposition of the Willow Sawfly Nematus oligospilus on Leaves of Salix spp. (Salicaceae).

Plant volatile organic compounds play a role in selection of host plants by herbivorous insects. Once the insect reaches the plant, contact cues determine host acceptance. Although the willow sawfly Nematus oligospilus (Hymenoptera: Tenthredinidae) can differentiate among willow genotypes, no knowledge is available on the cues used by this insect to seek and accept the host plant. In this study, we recorded behavioral orientation in a Y-tube olfactometer of willow sawfly females to volatiles of the highly preferred genotype Salix nigra and the non-preferred genotype S. viminalis. The volatiles released by undamaged willows of each genotype were analyzed by coupled gas chromatography-mass spectrometry. Contact cues were evaluated first by oviposition preference bioassays after selective leaf wax removal, and then by studying the micromorphology of abaxial and adaxial leaf surfaces and their chemical composition. Willow sawfly females oriented preferentially to S. nigra volatiles, which contained more than 3 times the amount of volatiles than that collected from S. viminalis. Analysis of volatiles showed significant differences in amounts of (Z) and (E)-ß-ocimene, undecane, decanal, and ß-caryophyllene. The adaxial leaf surface of S. nigra was less preferred after wax removal, suggesting a role of cuticular waxes for oviposition acceptance. No differences were found among the micromorphology of leaf surfaces between preferred and non-preferred genotypes. The chemical analysis of cuticular waxes showed that the abaxial leaf surface of S. viminalis, which is completely avoided for oviposition, possessed 97% of alkanes. The accepted leaf surfaces contained a more diverse wax profile including alcohols, acids, and esters. Thus, non-alkane wax compounds might be related to oviposition. In sum, our study suggests that several cues act in concert to provide oviposition cues for the sawfly N. oligospilus: females are attracted to volatiles from a distance, and once alighting on the plant, they seek specific chemical contact cues in order to lay eggs.

An emerging understanding of mechanisms governing insect herbivory under elevated CO2.

By changing the chemical composition of foliage, the increase in atmospheric CO(2) is fundamentally altering insect herbivory. The responses of folivorous insects to these changes is, however, highly variable. In this review we highlight emerging mechanisms by which increasing CO(2) alters the defense chemistry and signaling of plants. The response of allelochemicals affecting insect performance varies under elevated CO(2), and results suggest this is driven by changes in plant hormones. Increasing CO(2) suppresses the production of jasmonates and ethylene and increases the production of salicylic acid, and these differential responses of plant hormones affect specific secondary chemical pathways. In addition to changes in secondary chemistry, elevated CO(2) decreases rates of water loss from leaves, increases temperature and feeding rates, and alters nutritional content. New insights into the mechanistic responses of secondary chemistry to elevated CO(2) increase our ability to predict the ecological and evolutionary responses of plants attacked by insects.

Lipoxygenases regulate digestive enzyme inhibitor activities in developing seeds of field-grown soybean against the southern green stink bug (Nezara viridula).

Soybean (Glycine max ) is the world's most widely grown seed legume. One of the most important pests that decrease seed quality and reduce yield of soybean crops is the southern green stink bug (Nezara viridula ). Insect damage triggers accumulation of defensive compounds such as protease inhibitors (PIs), isoflavonoids and reactive oxygen species, which are regulated by the lipoxygenase (LOX)-regulated jasmonic acid (JA) to stop insect feeding. This study identified and characterised the role of LOX isoforms in the modulation of chemical defences in seeds of field-grown soybean that decreased digestive enzyme activities of N. viridula after insect attack. Stink bugs attack increased LOX 1 and LOX 2 expression, and activities of LOX 1 and LOX 3 isoenzymes in developing soybean seeds. In addition, stink bug damage and methyl jasmonate application induced expression and activity of both cysteine PIs and trypsin PIs in developing soybean seeds, suggesting that herbivory induced JA in soybean seeds. High PI activity levels in attacked seeds decreased cysteine proteases and α-amylases activities in the gut of stink bugs that fed on field-grown soybean. We demonstrated that LOX isoforms of seeds are concomitantly induced with JA-regulated PIs by stink bugs attack, and these PIs inhibit the activity of insect digestive enzymes. To our knowledge, this is the first study to investigate the participation of LOX in modulating JA-regulated defences against stink bugs in seeds of field-grown soybean, and our results suggest that soybean PIs may inhibit α-amylase activity in the gut of N. viridula .

Changes in primary metabolite content may affect thrips feeding preference in soybean crops.

Past research has characterized the induction of plant defenses in response to chewing insect damage. However, little is known about plant responses to piercing-sucking insects that feed on plant cell-contents like thrips (Caliothrips phaseoli). In this study, we used NMR spectroscopy to measure metabolite changes in response to six days of thrips damage from two field-grown soybean cultivars (cv.), known for their different susceptibility to Caliothrips phaseoli. We observed that thrips damage reduces sucrose concentration in both cultivars, while pinitol, the most abundant leaf soluble carbohydrate, is induced in cv. Charata but not in cv. Williams. Thrips did not show preference for leaves where sucrose or pinitol were externally added, at tested concentration. In addition, we also noted that cv. Charata was less naturally colonized and contained higher levels of trigonelline, tyrosine as well as several compounds that we have not yet identified. We have established that preference-feeding clues are not dependent on the plants major soluble carbohydrates but may depend on other types of compounds or leaf physical characteristics.

Herbivore induction of jasmonic acid and chemical defences reduce photosynthesis in Nicotiana attenuata.

Herbivory initiates a shift in plant metabolism from growth to defence that may reduce fitness in the absence of further herbivory. However, the defence-induced changes in carbon assimilation that precede this reallocation in resources remain largely undetermined. This study characterized the response of photosynthesis to herbivore induction of jasmonic acid (JA)-related defences in Nicotiana attenuata to increase understanding of these mechanisms. It was hypothesized that JA-induced defences would immediately reduce the component processes of photosynthesis upon attack and was predicted that wild-type plants would suffer greater reductions in photosynthesis than plants lacking JA-induced defences. Gas exchange, chlorophyll fluorescence, and thermal spatial patterns were measured together with the production of defence-related metabolites after attack and through recovery. Herbivore damage immediately reduced electron transport and gas exchange in wild-type plants, and gas exchange remained suppressed for several days after attack. The sustained reductions in gas exchange occurred concurrently with increased defence metabolites in wild-type plants, whereas plants lacking JA-induced defences suffered minimal suppression in photosynthesis and no increase in defence metabolite production. This suppression in photosynthesis occurred only after sustained defence signalling and defence chemical mobilization, whereas a short bout of feeding damage only transiently altered components of photosynthesis. It was identified that lipoxygenase signalling interacted with photosynthetic electron transport and that the resulting JA-related metabolites reduced photosynthesis. These data represent a metabolic cost to mounting a chemical defence against herbivory and link defence-signalling networks to the differential effects of herbivory on photosynthesis in remaining leaf tissues in a time-dependent manner.

Glyphosate affects larval gut microbiota and metamorphosis of honey bees with differences between rearing procedures.

The honey bee Apis mellifera is a sentinel species of the pollinator community which is exposed to a wide variety of pesticides. In the last half-century, the pesticide most applied worldwide has been the herbicide glyphosate (GLY) used for weed control and with microbiocide effects. After its application in crops, the GLY residues have been detected in flowers visited by honey bees as well as in the stored food of their hives. Therefore, the honey bee brood can ingest the herbicide during larval development. Recent studies proved that GLY has detrimental effects on adult honey bees and other insects associated with the disturbance of their gut microbiota. GLY induces changes in the growth, metabolism and survival of honey bees and stingless bees reared in vitro. However, the effect of GLY on larval microbiota is unknown so far and there are few studies with an in-hive exposure to GLY. For these reasons, this study aims to determine whether GLY induces dysbiosis in honey bee larvae and affects their metamorphosis during the exposure period (pre-defecation) and the post-exposure period. Furthermore, we assessed this herbicide in vitro and in the hive to compare its effects on different rearing procedures. Finally, we tested the pigment BLUE1 as an indirect exposure marker to detect and estimate the in-hive intake concentration of GLY. Our results indicate that the intake of field-relevant concentrations of GLY induced a slowdown in growth with dysbiosis in the larval gut microbiota followed by late effects on their metamorphosis such as teratogenesis and mortality of newly emerged bees. Nevertheless, brood from the same colonies expressed different signs of toxicity depending on the rearing procedure and in a dose-dependent manner.

Subacute ischemic stroke is associated with focal 11C PiB positron emission tomography retention but not with global neocortical Aß deposition.

BACKGROUND AND PURPOSE: Conflicting evidence exists as to whether focal cerebral ischemia contributes to cerebral amyloid deposition. We aimed to look at Aß deposits, detected by N-methyl-2-(4'-methylaminophenyl)-6-hydroxybenzothiazole (PiB) positron emission tomography, in patients with recent ischemic stroke. Specifically, we hypothesized that patients with recent ischemic stroke have higher local and neocortical PiB positron emission tomography retention and that this may be associated with major vascular risk factors. METHODS: Ischemic stroke patients were studied using PiB positron emission tomography within 30 days and compared to age-matched controls. Distribution volume ratio maps were created using Logan graphical analysis with the cerebellar cortex as a reference. RESULTS: Among the 21 ischemic stroke patients (median age, 76 years; interquartile range, 68-77), the ipsilateral peri-infarct region PiB retention was higher compared to the contralateral mirror region, with a PiB distribution volume ratio difference of 0.29 (95% CI, 0.2-0.44; P=0.001) at median 10 (interquartile range, 7-14) days after stroke. Two patients also had higher PiB retention within the infarct compared to the contralateral side. There was no difference in the neocortical PiB retention elsewhere in the brain among ischemic stroke patients compared with 22 age-matched normal controls (P=0.22). Among the risk factors in the ischemic stroke patients, diabetes was associated with a higher neocortical PiB retention (Spearman Rho=0.48; 95% CI, 0.28-0.72). CONCLUSIONS: PiB retention was higher in the peri-infarct region among patients with recent ischemic stroke. This did not translate into a higher global neocortical PiB retention except possibly in patients with diabetes. The cause of the focal PiB retention is uncertain and requires further investigation.

Feeding on soybean crops changed gut bacteria diversity of the southern green stinkbug (Nezara viridula) and reduced negative effects of some associated bacteria.

BACKGROUND: The southern green stinkbug (Nezara viridula) is a mayor pest of soybean. However, the mechanism underlying stinkbug resistance to soybean defenses is yet ignored. Although gut bacteria could play an essential role in tolerating plant defenses, most studies testing questions related to insect-plant-bacteria interactions have been performed in laboratory condition. Here we performed experiments in laboratory and field conditions with N. viridula and its gut bacteria, studying gut lipid peroxidaxion levels and cysteine activity in infected and unifected nymphs, testing the hypothesis that feeding on field-grown soybean decreases bacterial abundance in stinkbugs. RESULTS: Gut bacterial abundance and infection ratio were higher in N. viridula adults reared in laboratory than in those collected from soybean crops, suggesting that stinkbugs in field conditions may modulate gut bacterial colonization. Manipulating gut microbiota by infecting stinkbugs with Yokenella sp. showed that these bacteria abundance decreased in field conditions, and negatively affected stinkbugs performance and were more aggressive in laboratory rearing than in field conditions. Infected nymphs that fed on soybean pods had lower mortality, higher mass and shorter development period than those reared in the laboratory, and suggested that field conditions helped nymphs to recover from Yokenella sp. infection, despite of increased lipid peroxidation and decreased cysteine proteases activity in nymphs' guts. CONCLUSIONS: Our results demonstrated that feeding on field-grown soybean reduced bacterial abundance and infection in guts of N. viridula and highlighted the importance to test functional activities or pathogenicity of microbes under realistic field conditions prior to establish conclusions on three trophic interactions. © 2022 Society of Chemical Industry.

Chromosomal-level genome assembly of potato tuberworm, Phthorimaea operculella: a pest of solanaceous crops.

The potato tuberworm, Phthorimaea operculella Zeller, is an oligophagous pest feeding on crops mainly belonging to the family Solanaceae. It is one of the most destructive pests of potato worldwide and attacks foliage and tubers in the field and in storage. However, the lack of a high-quality reference genome has hindered the association of phenotypic traits with their genetic basis. Here, we report on the genome assembly of P. operculella at the chromosomal level. Using Illumina, Nanopore and Hi-C sequencing, a 648.2 Mb genome was generated from 665 contigs, with an N50 length of 3.2 Mb, and 92.0% (596/648.2 Mb) of the assembly was anchored to 29 chromosomes. In total, 16619 genes were annotated, and 92.4% of BUSCO genes were fully represented. The chromosome-level genome of P. operculella will provide a significant resource for understanding the genetic basis for the biological study of this insect, and for promoting the integrative management of this pest in future.

The hidden mismatch: an explanation for infarct growth without perfusion-weighted imaging/diffusion-weighted imaging mismatch in patients with acute ischemic stroke.

BACKGROUND AND PURPOSE: In ischemic stroke, MR perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) mismatch represents tissue at risk for infarction. Infarct growth should only take place in the presence of mismatch, although there have been reports of this occurring. We hypothesized that this observation may be attributable to the presence of undetected "hidden mismatch," which may become obvious when coregistration techniques are used. METHODS: MR PWI/DWI was performed within 48 hours of stroke onset and a final T2-weighted image at ≈3 months. Volumetric-subtraction mismatch volume was defined as PWI minus DWI volume and infarct growth was defined as T2 minus DWI volume. Coregistration mismatch volume was PWI not overlapped by DWI. Mismatch salvage was the proportion of coregistered mismatch tissue that had not progressed to infarction. RESULTS: Thirty-four patients were studied with MR at a median of 4.9 hours (interquartile range, 2.9-21.1 hours). With the volumetric-subtraction technique, 5 patients (14.7%; 95% CI, 0.05%-0.31%) had infarct growth exceeding mismatch volume, 11 patients (32.0%) had no mismatch and, among these, 3 (27.3%) had infarct growth (median volume, 2.2 mL; interquartile range, 1.0-6.5 mL). All patients had mismatch volume identified by coregistration method that was greater than infarct growth volume. The proportion of this volume salvaged was 77.7% (interquartile range, 63.0%-98.9%). CONCLUSIONS: The illogical finding of infarct growth volume being greater than the presence of mismatch volume can be explained by the presence of "hidden mismatch," which may be detected by coregistration methods.

Cerebral ß-amyloid detected by Pittsburgh compound B positron emission topography predisposes to recombinant tissue plasminogen activator-related hemorrhage.

Cerebral amyloid angiopathy (CAA) may be an important predisposing factor for the hemorrhagic complications of recombinant tissue-type plasminogen activator (rt-PA) therapy. We studied patients treated within 3 hours of onset of ischemic stroke with rt-PA using positron emission tomography to compare Pittsburgh compound B (PiB) (a cerebral ß-amyloid ligand) retention in those with and without parenchymal hemorrhage (PH) and normal controls. Neocortical PiB retention was higher among patients with PH compared with patients without PH and normal controls, suggesting underlying CAA as a predisposing factor for rt-PA-related hemorrhage. This finding may provide an impetus for the development of a more practical rapid pretreatment screening technique.

Anthropogenic increase in carbon dioxide compromises plant defense against invasive insects.

Elevated levels of atmospheric carbon dioxide (CO2), a consequence of anthropogenic global change, can profoundly affect the interactions between crop plants and insect pests and may promote yet another form of global change: the rapid establishment of invasive species. Elevated CO2 increased the susceptibility of soybean plants grown under field conditions to the invasive Japanese beetle (Popillia japonica) and to a variant of western corn rootworm (Diabrotica virgifera virgifera) resistant to crop rotation by down-regulating gene expression related to defense signaling [lipoxygenase 7 (lox7), lipoxygenase 8 (lox8), and 1-aminocyclopropane-1-carboxylate synthase (acc-s)]. The down-regulation of these genes, in turn, reduced the production of cysteine proteinase inhibitors (CystPIs), which are specific deterrents to coleopteran herbivores. Beetle herbivory increased CystPI activity to a greater degree in plants grown under ambient than under elevated CO2. Gut cysteine proteinase activity was higher in beetles consuming foliage of soybeans grown under elevated CO2 than in beetles consuming soybeans grown in ambient CO2, consistent with enhanced growth and development of these beetles on plants grown in elevated CO2. These findings suggest that predicted increases in soybean productivity under projected elevated CO2 levels may be reduced by increased susceptibility to invasive crop pests.

Evaluating the Impact of Post-Emergence Weed Control in Honeybee Colonies Located in Different Agricultural Surroundings.

The honeybee Apis mellifera is exposed to agricultural intensification, which leads to an improved reliance upon pesticide use and the reduction of floral diversity. In the present study, we assess the changes in the colony activity and the expression profile of genes involved in xenobiotic detoxification in larvae and adult honeybees from three apiaries located in agricultural environments that differ in their proportion of the crop/wild flora. We evaluated these variables before and after the administration of a mixture of three herbicides during the summer season. The expression of several cytochrome P450 monooxygenases decreased significantly in larvae after post-emergence weed control and showed significant differences between apiaries in the case of honeybee workers. Principal component analysis (PCA) revealed that colonies located in the plot near to a wetland area exhibited a different relative gene expression profile after herbicide application compared with the other plots. Moreover, we found significant positive correlations between pollen collection and the pesticide detoxification genes that discriminated between plots in the PCA. Our results suggest that nutrition may modify herbicide impact on honeybees and that larvae are more harmed than adults in agroecosystems, a factor that will alter the colonies' population growth at the end of the blooming period.

Proteases inhibitors-insensitive cysteine proteases allow Nezara viridula to feed on growing seeds of field-grown soybean.

The southern green stink bug, Nezara viridula is one of the primary soybean pests and causes significant economic losses around the world. In spite of the high proteases inhibitor (PI) levels, N. viridula can feed on developing seeds of field-grown soybean and reduce crop yields. Although the PI-induced responses have been extensively investigated in many pest insects, there is lack of knowledge about the mechanisms that stink bugs employ to withstand cysteine PIs of soybean seeds. This study demonstrated that feeding on developing seeds of field-grown soybean inhibited total proteases activity of N. viridula, as result of inhibition of cathepsin B-like activity in the gut. In addition, from the 30 digestive cathepsins recognized in this study, 6 were identified as cathepsin B-like. Stink bugs that fed on growing seeds of field-grown soybean had similar gut pH to those reared in the laboratory, and both cathepsin B- and L-like had an optima pH of 6.5. Therefore, using specific proteases inhibitors we found that the main proteolytic activity in the gut is from cysteine proteases when N. viridula feeds on soybean crops. Since cathepsin L-like activity was not inhibited by soybean PIs, our results suggested that N. viridula relays on cathepsin L-like to feed on soybean. To our knowledge no study before has shown the impact of seed PIs of field-grown soybean on digestive proteases (cathepsin B- and L-like) of N. viridula. This study suggests that the activity of PI-insensitive cathepsins L-like in the gut would be part of an adaptive strategy to feed on developing soybean seeds. In agreement, the expansions of cathepsin L-like complement observed in pentatomids could confer to the insects a higher versatility to counteract the effects of different PIs.

Biotic stress globally downregulates photosynthesis genes.

To determine if damage to foliage by biotic agents, including arthropods, fungi, bacteria and viral pathogens, universally downregulates the expression of genes involved in photosynthesis, we compared transcriptome data from microarray experiments after twenty two different forms of biotic damage on eight different plant species. Transcript levels of photosynthesis light reaction, carbon reduction cycle and pigment synthesis genes decreased regardless of the type of biotic attack. The corresponding upregulation of genes coding for the synthesis of jasmonic acid and those involved in the responses to salicylic acid and ethylene suggest that the downregulation of photosynthesis-related genes was part of a defence response. Analysis of the sub-cellular targeting of co-expressed gene clusters revealed that the transcript levels of 84% of the genes that carry a chloroplast targeting peptide sequence decreased. The majority of these downregulated genes shared common regulatory elements, such as G-box (CACGTG), T-box (ACTTTG) and SORLIP (GCCAC) motifs. Strong convergence in the response of transcription suggests that the universal downregulation of photosynthesis-related gene expression is an adaptive response to biotic attack. We hypothesize that slow turnover of many photosynthetic proteins allows plants to invest resources in immediate defence needs without debilitating near term losses in photosynthetic capacity.