Microtubule-mediated defence reaction of grapevine to Neofusicoccum
parvum via the transcription factor VrWRKY22 promoting the Kinesin-like
protein VrKIN10C
Abstract
Grapevine Trunk Diseases (GTDs) are among the most destructive diseases
in viticulture due to global climate change. Some causal agents like
Neofusicoccum parvum can be latent endophytic and become
pathogenic under abiotic stress. Microtubules (MTs) have been found to
play a role in mediating the pathogen-related signaling in grapevine. In
this study, a novel transcription factor VrWRKY22 was identified
and cloned from the native American grapevine Vitis rupestris.
Leaves of the table grape variety ‘Kyoho’ ( V. vinifera × V.
labrusca L.) overexpressing VrWRKY22 showed less necroses after
N. parvum Bt‐67 inoculation and activated signaling pathways.
VrWRKY22 was phosphorylated by VrMPK3 and then bound to
the TTGACC motif in the promoter of VrKIN10C, which was confirmed
by Y2H and Y1H assays. Since VrKIN10C is one of the important
kinesin-like proteins associated with microtubules, a grapevine MT
marker line overexpressing VrWRKY22 was generated to test the
responses of grapevine cells to N. parvum Bt‐67. An increased
number of prompt movement proteins can be traced within the peri-nuclear
MTs and along the cortical MTs. The skewness and thickness of both
central and cortical MTs were significantly increased. Moreover, a
prominent (resulting from both the number and the rate) accumulation of
speckles appeared in the nucleus and cortical MTs. A significant
reduction in cell mortality and a stronger antioxidant capacity were
detected. This study demonstrates that VrWRKY22 plays positive
roles during N. parvum Bt‐67 invasion by rapidly increasing the
concentration and dynamics of MTs in the peri-nuclear and cortical
regions via VrKIN10, and will facilitate the interpretation of
the results of further GTD mitigation studies.