VqMAPKKK38 is essential for stilbene accumulation in grapevine

Vitis species,including grapevine,produce a class of secondary metabolites called stilbenes that are important for plant disease resistance and can have positive effects on human health.Mitogen-activated protein kinase(MAPK)signaling cascades not only play key roles in plant defense responses but also contribute to stilbene biosynthesis in grapevine.MAPKKKs function at the upper level of the MAPK network and initiate signaling through this pathway.In this study,a Raf-like MAPKKK gene,VqMAPKKK38,was identified and functionally characterized from the Chinese wild grapevine V.quinquangularis accession‘Danfeng-2’.We observed that VqMAPKKK38 transcript levels were elevated by powdery mildew infection,high salinity conditions and chilling stresses,as well as in response to treatments by the hormones salicylic acid(SA),methyl jasmonate(MeJA),ethylene(Eth)and abscisic acid(ABA).In addition,based on both transient overexpression and gene suppression of VqMAPKKK38 in grapevine leaves,we found that VqMAPKKK38 positively regulates stilbene synthase transcription and stilbene accumulation probably by mediating the activation of the transcription factor MYB14.In addition,both hydrogen peroxide(H2O2)and calcium influx activated VqMAPKKK38 expression and stilbene biosynthesis,which suggests that VqMAPKKK38 may be involved in the calcium signaling and ROS signaling pathways.

Identification of long non-coding RNAs in response to downy mildew stress in grape

The importance of long non-coding RNA in plants has been reported more frequently in recent years,but there has been few specific reports on lncRNAs in grape,especially in terms of disease resistance.We performed RNA-seq on grape leaves of two species(Vitis piasezkii accession Liuba-8,Vitis vinifera cultivar Pinot Noir)sampled at six time points after inoculation,and 4011 possible lncRNAs were identified.The characteristics of grape lncRNAs were analyzed,and it was found that lncRNAs showed relatively consistent characteristics with the reported lncRNAs in model plants.3,643 lncRNAs were predicted that have cis-regulatory effects on 6,622 protein-coding genes and 91 DElncRNAs were revealed to be coexpressed with its trans-regulated coding genes.One hundred and seventeen grape microRNAs were predicted to potentially target 184 lncRNAs and six lncRNAs were predicted to be endogenous targeting mimics of 15 microRNAs,among which some miRNAs have been reported in grape disease resistance.At six time points,LncRNAs showed different expression levels and different expression patterns in two species,suggesting that lncRNAs may have a certain regulatory effect on resistance to downy mildew in grape.Finally,a lncRNA MSTRG.12742.1 which may play a positive role in grape downy mildew resistance was verified by transient transformation.Its potential target gene,VIT_204s0008g02671.1,encodes cryptochrome DASH which may regulate stomatal opening and closing of plant leaves.In this study,we provided the systematic identification of lncRNAs in the course of downy mildew of grape,laying a foundation for further studies on downy mildew and lncRNAs of grape in the future.