Functional characterization of WRKY46 in grape and its putative role in the interaction between grape and phylloxera (Daktulosphaira vitifoliae)

Abstract

WRKY transcription factors are involved in defense responses caused by biotic stresses. Phylloxera (Daktulosphaira vitifoliae Fitch), a pest widespread in viticulture, elicits transcriptional reprogramming of plant defense-associated components, such as regulons related to WRKYs and salicylic acid (SA) signaling. In this study, we characterized WRKY46, a WRKY transcription factor responsible for phylloxera attack, and revealed the molecular mechanism for WRKY-mediated defense responses to phylloxera. qRT-PCR and GUS staining analyses revealed that WRKY46 is induced in response to phylloxera damage and mechanical wounding. VvWRKY46 is a nuclear-localized transcription factor that activates its downstream target VvCHIB by direct protein–DNA interaction. Regulons involved in the SA-mediated defense response were regulated during incompatible interactions between “1103 Paulsen” rootstock and phylloxera. In addition, WRKY46 exhibited a higher transcript abundance in “1103 Paulsen” than in “Crimson Seedless”, regardless of whether the plants were infected with phylloxera. Furthermore, the enhanced expression of VvWRKY46 significantly attenuated phylloxera attack and delayed nymph development of composite grape plants. In summary, we demonstrated that WRKY46 plays a role in the SA-mediated defense-regulatory network by directly binding to the downstream structural gene VvCHIB. The phylloxera-responsive gene WRKY46 was identified, which could improve the understanding of the basic mechanism of grapevine in response to phylloxera.

Comparative Transcriptome Analysis of Two Root-Feeding Grape Phylloxera (D. vitifoliae) Lineages Feeding on a Rootstock and V. vinifera

“…Five WRKY transcription factors ( VviWRKY72/41/33/45/46 ) were shown to be higher expressed by the rootstock cultivar 140Ru as compared to V. vinifera cv. “Crimson Seedless” under grape phylloxera attack, implying an increased defense potential of grapevine rootstock cultivars [ 18 ]. In the presented study, we did not detect biotypic-specific grape phylloxera effector candidates with direct interaction to the Vitis WRKY transcription factors.…”

“…host plants by imbibing the cellular content retrieved from the nutritive organoid root or histoid leaf galls [ 8 , 9 , 10 ]. Grape phylloxera root infestation manipulates the host vine physiology by modulating the water, mineral, and assimilate transport pathways [ 11 , 12 , 13 ], interfering with host plant defense mechanisms [ 14 , 15 , 16 , 17 , 18 ] and facilitating secondary root infections by phytopathogenic soil-borne microorganisms [ 19 ], altogether leading to host plant damage or even vine death depending on concomitant biotic and abiotic environmental factors [ 20 , 21 ]. Motile grape phylloxera L1 larvae move and probe Vitis spp.…”

The VvWRKY37 Regulates Bud Break in Grape Vine Through ABA-Mediated Signaling Pathways

“…A previously described method was used to investigate the transcriptional activity of VvWRKY37 and its binding activities to downstream target genes ( Wang F. et al, 2019 ). The full-length coding sequence of VvWRKY37 was inserted into the pGADT7 vector to generate the effect or construct, and binding sequence Box 2 (5′-ATTGACTTGACCGTCATCGG-3′) was introduced into the upstream region of the HIS3 mini-promoter to generate the reporter construct.…”

“…Partially expanded grape vine leaves were used for a transient expression assay via A. tumefaciens inoculation as described earlier ( Wang F. et al, 2019 ). Histochemical staining was conducted for a GUS reporter assay after inoculation and in vitro co-cultivation for 3–5 days.…”

Involvement of CsWRKY70 in salicylic acid-induced citrus fruit resistance against Penicillium digitatum

“…The WRKY gene family is one of the largest transcription factor (TF) families in higher plants 16,17 . WRKY TFs (WRKYs) contain a DNA-binding domain that includes one or two highly conserved WRKYGQK motifs that follow a specific zinc-finger motif in the C terminus 16,17 . WRKYs participate in many biological processes, the best known of which is their pivotal role in plant defense responses 18 .…”