A Functional Genomics Approach Identifies Candidate Effectors from the Aphid Species Myzus persicae (Green Peach Aphid)

Aphids are amongst the most devastating sap-feeding insects of plants. Like most plant parasites, aphids require intimate associations with their host plants to gain access to nutrients. Aphid feeding induces responses such as clogging of phloem sieve elements and callose formation, which are suppressed by unknown molecules, probably proteins, in aphid saliva. Therefore, it is likely that aphids, like plant pathogens, deliver proteins (effectors) inside their hosts to modulate host cell processes, suppress plant defenses, and promote infestation. We exploited publicly available aphid salivary gland expressed sequence tags (ESTs) to apply a functional genomics approach for identification of candidate effectors from Myzus persicae (green peach aphid), based on common features of plant pathogen effectors. A total of 48 effector candidates were identified, cloned, and subjected to transient overexpression in Nicotiana benthamiana to assay for elicitation of a phenotype, suppression of the Pathogen-Associated Molecular Pattern (PAMP)–mediated oxidative burst, and effects on aphid reproductive performance. We identified one candidate effector, Mp10, which specifically induced chlorosis and local cell death in N. benthamiana and conferred avirulence to recombinant Potato virus X (PVX) expressing Mp10, PVX-Mp10, in N. tabacum, indicating that this protein may trigger plant defenses. The ubiquitin-ligase associated protein SGT1 was required for the Mp10-mediated chlorosis response in N. benthamiana. Mp10 also suppressed the oxidative burst induced by flg22, but not by chitin. Aphid fecundity assays revealed that in planta overexpression of Mp10 and Mp42 reduced aphid fecundity, whereas another effector candidate, MpC002, enhanced aphid fecundity. Thus, these results suggest that, although Mp10 suppresses flg22-triggered immunity, it triggers a defense response, resulting in an overall decrease in aphid performance in the fecundity assays. Overall, we identified aphid salivary proteins that share features with plant pathogen effectors and therefore may function as aphid effectors by perturbing host cellular processes

Measurement of the diffractive cross-section in deep inelastic scattering using ZEUS 1994 data

The DIS diffractive cross section, d sigma(gamma*p-->XN)(diff)/dM(X), has been measured in the mass range M(X) XN)(diff) (M(X), W, Q(2))/dM(X) proportional to W(adiff) with a(diff) = 0.507 +/- 0.034(stat)(-0.046)(+0.155) (syst) corresponding to a t-averaged pomeron trajectory of (P) = 1.127 +/- 0.009(stat)(-0.012)(+0.039) (syst) which is larger than (P) observed in hadron-hadron scattering The W dependence of the diffractive cross section is found to be the same as that of the total cross section for scattering of virtual photons on protons. The data are consistent with the assumption that the diffractive structure function F(2)(D(3)) factorizes according to x(P)F(2)(D(3))(x(p), beta, Q(2)) = (x(0)/x(P))(n)F(2)(D(2)) (beta, Q(2)). They are also consistent with QCD based models which incorporate factorization breaking. The rise of x(P)F(2)(D(3)) with decreasing x(P) and the weak dependence of F(2)(D(2)) On Q(2) suggest a substantial contribution from partonic interactions

EXTRACTION OF THE GLUON DENSITY OF THE PROTON AT X RID B-9165-2008 RID C-5889-2009 RID A-4818-2008 RID C-1693-2008

The gluon momentum density xg(x, Q(2)) of the proton was extracted at Q(2) = 20 GeV2 for small values of x between 4 x 10(-4) and 10(-2) from the scaling violations of the proton structure function F-2 measured recently by ZEUS in deep inelastic neutral current ep scattering at HERA. The extraction was performed in two ways. Firstly, using a global NLO fit to the ZEUS data on F-2 at low x constrained by measurements from NMC at larger x; and secondly using published approximate methods for the solution of the GLAP QCD evolution equations. Consistent results are obtained. A substantial increase of the gluon density is found at small x in comparison with the NMC result obtained at larger values of x

Measurement of the diffractive cross section in deep inelastic scattering using ZEUS 1994 data

The DIS diffractive cross section, dσdiffγ*p→XN/dMx, has been measured in the mass range Mx < 15 GeV for γ*p c.m. energies 60 < W < 200 GeV and photon virtualities Q2 = 7 to 140 GeV2. For fixed Q2 and Mx, the diffractive cross section rises rapidly with W, dσdiffγ*p→X N (Mx, W, Q2)/dMx ∝ Wadiff with adiff = 0.507 ± 0.034 (stat) +0.155-0.046 (syst) corresponding to a t-averaged pomeron trajectory of ̄αℙ = 1.127 ± 0.009 (stat) +0.039-0.012 (syst) which is larger than ̄αℙ observed in hadron-hadron scattering. The W dependence of the diffractive cross section is found to be the same as that of the total cross section for scattering of virtual photons on protons. The data are consistent with the assumption that the diffractive structure function FD(3)2 factorizes according to cursive greek chiℙFD(3)2(cursive greek chiℙ, β, Q2) = (cursive greek chi0//cursive greek chiℙ)nFD(2)2(β, Q2). They are also consistent with QCD based models which incorporate factorization breaking. The rise of cursive greek chiℙFD(3)2 with decreasing cursive greek chiℙ and the weak dependence of FD(2)2 on Q2 suggest a substantial contribution from partonic interactions

MEASUREMENT OF THE DIFFRACTIVE STRUCTURE-FUNCTION IN DEEP-INELASTIC SCATTERING AT HERA RID B-9165-2008 RID C-5889-2009 RID A-4818-2008 RID C-1693-2008

This paper presents an analysis of the inclusive properties of diffractive deep inelastic scattering events produced in ep interactions at HERA. The events are characterised by a rapidity gap between the outgoing proton system and the remaining hadronic system. Inclusive distributions are presented and compared with Monte Carlo models for diffractive processes. The data are consistent with models where the pomeron structure function has a hard and a soft contribution. The diffractive structure function is measured as a function of x(p), the momentum fraction lost by the proton, of beta, the momentum fraction of the struck quark with respect to x(p), and of Q(2) in the range 6.3 10(-4) < x(p) < 10(-2), 0.1 < .beta < 0.8 and 8 < Q(2) < 100 GeV2. The x(p) dependence is consistent with the form (1/x(p))(alpha) where alpha = 1.30 +/- 0.08 (stat)(-0.14)(+0.08) (sys) in all bins of beta and Q(2). In the measured Q(2) range, the diffractive structure function approximately scales with Q(2) at fixed beta. In an Ingelman-Schlein type model where commonly used pomeron flux factor normalisations are assumed, it is found that the quarks within the pomeron do not saturate the momentum sum rule

Extraction of the Gluon Density of the Proton At X

The gluon momentum density xg(x, Q(2)) of the proton was extracted at Q(2) = 20 GeV2 for small values of x between 4 x 10(-4) and 10(-2) from the scaling violations of the proton structure function F-2 measured recently by ZEUS in deep inelastic neutral current ep scattering at HERA. The extraction was performed in two ways. Firstly, using a global NLO fit to the ZEUS data on F-2 at low x constrained by measurements from NMC at larger x; and secondly using published approximate methods for the solution of the GLAP QCD evolution equations. Consistent results are obtained. A substantial increase of the gluon density is found at small x in comparison with the NMC result obtained at larger values of x

Measurement of the diffractive cross section in deep inelastic scattering using ZEUS 1994 data

The DIS diffractive cross section, d sigma(gamma*p-->XN)(diff)/dM(X), has been measured in the mass range M(X) XN)(diff) (M(X), W, Q(2))/dM(X) proportional to W(adiff) with a(diff) = 0.507 +/- 0.034(stat)(-0.046)(+0.155) (syst) corresponding to a t-averaged pomeron trajectory of (P) = 1.127 +/- 0.009(stat)(-0.012)(+0.039) (syst) which is larger than (P) observed in hadron-hadron scattering The W dependence of the diffractive cross section is found to be the same as that of the total cross section for scattering of virtual photons on protons. The data are consistent with the assumption that the diffractive structure function F(2)(D(3)) factorizes according to x(P)F(2)(D(3))(x(p), beta, Q(2)) = (x(0)/x(P))(n)F(2)(D(2)) (beta, Q(2)). They are also consistent with QCD based models which incorporate factorization breaking. The rise of x(P)F(2)(D(3)) with decreasing x(P) and the weak dependence of F(2)(D(2)) On Q(2) suggest a substantial contribution from partonic interactions

Measurement of inclusive D*(+/-) and associated dijet cross sections in photoproduction at HERA

Inclusive photoproduction of D*(+/-) mesons has been measured for photon-proton centre-of-mass energies in the range 130 < W < 280GeV and photon virtuality Q(2) < 1 GeV2. The data sample used corresponds to an integrated luminosity of 37 pb(-1). Total and differential cross sections as functions of the D* transverse momentum and pseudorapidity are presented in restricted kinematical regions and the data are compared with next-to-leading order (NLO) perturbative QCD calculations using the "massive charm" and "massless charm" schemes. The measured cross sections are generally above the NLO calculations, in particular in the forward (proton) direction. The large data sample also allows the study of dijet production associated with charm. A significant resolved as well as a direct photon component contribute to the cross section. Leading order QCD Monte Carlo calculations indicate that the resolved contribution arises from a significant charm component in the photon. A massive charm NLO parton level calculation yields lower cross sections compared to the measured results in a kinematic region where the resolved photon contribution is significant