Plant calmodulins (CaMs) and calmodulin-like proteins (CMLs) are important plant Ca²⁺-binding proteins that sense and decode changes in the intracellular Ca²⁺ concentration arising in response to environmental stimuli. Protein Ca²⁺ sensors are presented by complex gene families in plants and perform diverse biological functions. In this study, we cloned, sequenced, and characterized three CaM and 54 CML mRNA transcripts of Vitis amurensis Rupr., a wild-growing grapevine with a remarkable stress tolerance. Using real-time quantitative RT-PCR, we analyzed transcript abundance of the identified VaCaMs and VaCMLs in response to water deficit, high salinity, high mannitol, cold and heat stresses. Expression of VaCaMs and 32 VaCMLs actively responded to the abiotic stresses and exhibited both positive and negative regulation patterns. Other VaCML members showed slight transcriptional regulation, remained essentially unresponsive or responded only after one time interval of the treatments. The substantial alterations in the VaCaM and VaCML transcript levels revealed their involvement in the adaptation of wild-growing grapevine to environmental stresses.

Grapevine endophytic fungi have great potential for application in agriculture and represent an important source of various compounds with valuable biological activities. Wild grapevine is known to host a great number of rare and unidentified endophytes and may represent a rich repository of potential vineyard biocontrol agents. This investigation aimed to study the fungal endophytic community of wild grape Vitis amurensis Rupr. using a cultivation-dependent (fungi sowing) and a cultivation-independent (next-generation sequencing, NGS) approach. A comprehensive analysis of the endophytic fungal community in different organs of V. amurensis and under different environmental conditions has been performed. According to the NGS analysis, 12 taxa of class level were presented in different grapevine organs (stem, leaf, berry, seed). Among the 12 taxa, sequences of two fungal classes were the most represented: Dothideomycetes—60% and Tremellomycetes—33%. The top five taxa included Vishniacozyma, Aureobasidiaceae, Cladosporium, Septoria and Papiliotrema. The highest number of fungal isolates and sequences were detected in the grape leaves. The present data also revealed that lower temperatures and increased precipitation favored the number and diversity of endophytic fungi in the wild Amur grape. The number of fungi recovered from grape tissues in autumn was two times higher than in summer. Thus, this study is the first to describe and analyze the biodiversity of the endophytic fungal community in wild grapevine V. amurensis.

Calmodulin-like proteins (CMLs) are an important family of plant calcium sensor proteins that sense and decode changes in the intracellular calcium concentration in response to environmental and developmental stimuli. Nonetheless, the specific functions of individual CML family members remain largely unknown. This study aims to explore the role of the Vitis amurensis VaCML92 gene in the development of its high stress resistance and the production of stilbenes. The expression of VaCML92 was sharply induced in V. amurensis cuttings after cold stress. The VaCML92 gene was cloned and its role in the abiotic stress responses and stilbene production in grapevine was further investigated. The VaCML92-overexpressing callus cell cultures of V. amurensis and soil-grown plants of Arabidopsis thaliana exhibited enhanced tolerance to cold stress and, to a lesser extent, to the drought, while their tolerance to heat stress and high salinity was not affected. In addition, the overexpression of VaCML92 increased stilbene production in the V. amurensis cell cultures by 7.8–8.7-fold. Taken together, the data indicate that the VaCML92 gene is involved as a strong positive regulator in the rapid response to cold stress, the induction of cold stress resistance and in stilbene production in wild grapevine.

The most serious problems for cultivated grapes are pathogenic microorganisms, which reduce the yield and quality of fruit. One of the most widespread disease of grapes is “gray mold”, caused by the fungus Botrytis cinerea. Some strains of Bacillus, such as Bacillus halotolerans, Bacillus amyloliquefaciens, and Bacillus velezensis, are known to be active against major post-harvest plant rots. In this study, we showed that the endophytic bacteria B. velezensis strain AMR25 isolated from the leaves of wild grapes Vitis amurensis Rupr. exhibited antimicrobial activity against grape pathogens, including B. cinerea. The genome of B. velezensis AMR25 has one circular chromosome with a length of 3,909,646 bp. with 3689 open reading frames. Genomic analysis identified ten gene clusters involved in the nonribosomal synthesis of polyketides (macrolactin, bacillene, and difficidin), lipopeptides (surfactin, fengycin, and bacillizin), and bacteriocins (difficidin). Also, the genome under study contains a number of genes involved in root colonization, biofilm formation, and biosynthesis of phytohormones. Thus, the endophytic bacteria B. velezensis strain AMR25 shows great promise in developing innovative biological products for enhancing plant resistance against various pathogens.

Stilbenes are a group of plant phenolic secondary metabolites, with trans-resveratrol (3,5,4′-trihydroxy-trans-stilbene) being recognized as the most prominent and studied member. Stilbenes have a great potential for use in agriculture and medicine, as they have significant activities against plant pathogens and have valuable beneficial effects on human health. In this study, we analyzed the effects of direct application of stilbenes, stilbene precursor, and stilbene-rich extract solutions to the plant foliar surface for increasing the resistance of Arabidopsis thaliana to various abiotic stresses (heat, cold, drought, and soil salinity). Exogenous treatment of A. thaliana with stilbenes (trans-resveratrol, piceid, and spruce bark extract) and phenolic precursor (p-coumaric acid or CA) during germination resulted in considerable growth retardation of A. thaliana plants: a strong delay in the root and stem length of 1-week-old seedlings (in 1.3–4.5 fold) and rosette diameter of 1-month-old plants (in 1.2–1.8 fold), while the 2-month-old treated plants were not significantly different in size from the control. Plant treatments with stilbenes and CA increased the resistance of A. thaliana to heat and, to a lesser extent, to soil salinity (only t-resveratrol and spruce extract) to drought (only CA), while cold resistance was not affected. Plant treatments with stilbenes and CA resulted in a significant increase in plant resistance and survival rates under heat, with plants showing 1.5–2.3 times higher survival rates compared to untreated plants. Thus, exogenous stilbenes and a CA are able to improve plant survival under certain abiotic stresses via specific activation of the genes involved in the biosynthesis of auxins, gibberellins, abscisic acid, and some stress-related genes. The present work provides new insights into the application of stilbenes to improve plant stress tolerance.

Many grape endophytic microorganisms exhibit high potential for suppressing the development of grape diseases and stimulating grapevine growth and fitness, as well as beneficial properties of the crop. The microbiome of wild grapevines is a promising source of biocontrol agents, which can be beneficial for domesticated grapevines. Using next-generation sequencing (NGS) and classical microbiology techniques, we performed an analysis of bacterial and fungal endophytic communities of wild grapevines Vitis amurensis Rupr. and Vitis coignetiae Pulliat growing in the Russian Far East. According to the NGS analysis, 24 and 18 bacterial taxa from the class level were present in V. amurensis and V. coignetiae grapevines, respectively. Gammaproteobacteria (35%) was the predominant class of endophytic bacteria in V. amurensis and Alphaproteobacteria (46%) in V. coignetiae. Three taxa, namely Sphingomonas, Methylobacterium, and Hymenobacter, were the most common bacterial genera for V. amurensis and V. coignetiae. Metagenomic analysis showed the presence of 23 and 22 fungi and fungus-like taxa of class level in V. amurensis and V. coignetiae, respectively. The predominant fungal classes were Dothideomycetes (61–65%) and Tremellomycetes (10–11%), while Cladosporium and Aureobasidium were the most common fungal genera in V. amurensis and V. coignetiae, respectively. A comparative analysis of the endophytic communities of V. amurensis and V. coignetiae with the previously reported endophytic communities of V. vinifera revealed that the bacterial biodiversity of V. amurensis and V. coignetiae was similar in alpha diversity to V. vinifera’s bacterial biodiversity. The fungal alpha diversity of V. amurensis and V. coignetiae was statistically different from that of V. vinifera. The beta diversity analysis of bacterial and fungal endophytes showed that samples of V. vinifera formed separate clusters, while V. amurensis samples formed a separate cluster including V. coignetiae samples. The data revealed that the endophytic community of bacteria and fungi from wild V. amurensis was richer than that from V. coignetiae grapes and cultivated V. vinifera grapes. Therefore, the data obtained in this work could be of high value in the search for potentially useful microorganisms for viticulture.