Harpin-induced expression and transgenic overexpression of the phloem protein gene AtPP2-A1 in Arabidopsis repress phloem feeding of the green peach aphid Myzus persicae

Abstract

BackgroundTreatment of plants with HrpNEa, a protein of harpin group produced by Gram-negative plant pathogenic bacteria, induces plant resistance to insect herbivores, including the green peach aphid Myzus persicae, a generalist phloem-feeding insect. Under attacks by phloem-feeding insects, plants defend themselves using the phloem-based defense mechanism, which is supposed to involve the phloem protein 2 (PP2), one of the most abundant proteins in the phloem sap. The purpose of this study was to obtain genetic evidence for the function of the Arabidopsis thaliana (Arabidopsis) PP2-encoding gene AtPP2-A1 in resistance to M. persicae when the plant was treated with HrpNEa and after the plant was transformed with AtPP2-A1.ResultsThe electrical penetration graph technique was used to visualize the phloem-feeding activities of apterous agamic M. persicae females on leaves of Arabidopsis plants treated with HrpNEa and an inactive protein control, respectively. A repression of phloem feeding was induced by HrpNEa in wild-type (WT) Arabidopsis but not in atpp2-a1/E/142, the plant mutant that had a defect in the AtPP2-A1 gene, the most HrpNEa-responsive of 30 AtPP2 genes. In WT rather than atpp2-a1/E/142, the deterrent effect of HrpNEa treatment on the phloem-feeding activity accompanied an enhancement of AtPP2-A1 expression. In PP2OETAt (AtPP2-A1-overexpression transgenic Arabidopsis thaliana) plants, abundant amounts of the AtPP2-A1 gene transcript were detected in different organs, including leaves, stems, calyces, and petals. All these organs had a deterrent effect on the phloem-feeding activity compared with the same organs of the transgenic control plant. When a large-scale aphid population was monitored for 24 hours, there was a significant decrease in the number of aphids that colonized leaves of HrpNEa-treated WT and PP2OETAt plants, respectively, compared with control plants.ConclusionsThe repression in phloem-feeding activities of M. persicae as a result of AtPP2-A1 overexpression, and as a deterrent effect of HrpNEa treatment in WT Arabidopsis rather than the atpp2-a1/E/142 mutant suggest that AtPP2-A1 plays a role in plant resistance to the insect, particularly at the phloem-feeding stage. The accompanied change of aphid population in leaf colonies suggests that the function of AtPP2-A1 is related to colonization of the plant.

HrpNEa-induced deterrent effect on phloem feeding of the green peach aphid Myzus persicae requires AtGSL5 and AtMYB44 genes in Arabidopsis thaliana

“…On comparison of the plant mutants atmyb44 and atgsl5-1, atmyb44 is found to be more susceptible to aphids and more inhibitive to the HrpN Ea -induced deterrent effect on the phloem-feeding activity. These results indicate other components, besides AtGSL5 and callose, are involved in HrpN Ea -induced resistance to M. persicae in the plant (Zhang et al 2011), and especially support the function of AtMYB44 as a regulator of the induced resistance Liu et al 2010a,b). It would be great of interest to study in the future the physiological connection between AtMYB44 and AtGSL5 during induction of the defense.…”

Enzymatic study on AtCCD4 and AtCCD7 and their potential to form acyclic regulatory metabolites

“…CCD4 enzymes, the subject of this study, regulate carotenoid homeostasis in different tissues, such as Arabidopsis seeds (Gonzalez-Jorge et al , 2013), chrysanthemum petals (Ohmiya et al , 2006), and peach fruit pulp (Brandi et al , 2011; Falchi et al , 2013). CCD4 enzymes from Crocus , Chrysanthemum , and apple produce β-ionone, indicating a single or double cleavage activity at the C9–C10 and/or the C9'–C10' double bond in β-carotene (Rubio et al , 2008; Huang et al , 2009).…”

Tobacco TTG2 Quells Resistance to Pathogens by Sequestering NPR1 from Nuclear Localisation

“…The fifth to seventh youngest leaves were used to prepare total protein (Liu et al, 2006), cytoplasmic protein (Zhang et al, 2011) and nuclear protein (Kinkema et al, 2000) samples. Western blots were hybridised with GFP antibody from Novagen or NtTTG2 antibody produced by immunising New Zealand white rabbits (Oryctolagus cuniculus) as previously described (Sun et al, 2010b).…”