Nudix hydrolases are widely distributed across all classes of organisms and provide the potential capacity to hydrolyze a wide range of organic pyrophosphates.  Although Nudix hydrolases are involved in plant detoxification processes in response to abiotic and biotic stresses, the biological functions of Nudix hydrolases remain largely unclear in grapevine.  In the present study, a total of 25 putative grapevine Nudix hydrolases (VvNUDXs) were identified by bioinformatics analysis and classified into eight subfamilies based to their preferred substrates.  Both tandem and segmental duplications were responsible for the evolution and expansion of the NUDX gene family in grapevine.  To investigate the regulatory roles of VvNUDX genes during growth and development, as well as in response to abiotic and biotic stresses in grapevine, the expression patterns were revealed in publicly available microarray data.  The spatial and temporal expression patterns of the VvNUDX genes indicated that they might play important roles in multiple developmental processes.  Transcriptome and qRT-PCR analyses showed that ten VvNUDX genes were specifically expressed in grapevine berries, suggesting potential roles in grapevine berry development.  Expression and phylogenetic analyses demonstrated that VvNUDX1 and VvNUDX3 might be involved in terpenoid biosynthesis in grapevine.  Furthermore, most VvNUDX genes active toward the ADP-ribose/NADH showed different patterns in response to various abiotic and biotic stresses, such as salinity and drought, as well as different types of biotic treatments, such as Erysiphe necator, Bois Noir phytoplasma and leaf-roll-associated virus-3 (GLRaV-3).  These results indicated that VvNUDX genes were associated with plant detoxification processes in response to abiotic and biotic stresses, and regulate the disease immunity and resistance pathways.  The information obtained here may provide good opportunities to explore the physiological functions of VvNUDX genes in berry development and stress response networks in grapevine. 

Bacillus subtilis strain NCD-2 is an excellent biocontrol agent for plant soil-borne diseases, and the lipopeptide fengycin is one of the active antifungal compounds in strain NCD-2.  The regulator phoP and its sensor kinase PhoR compose a two-component system in B. subtilis.  In this study, the phoR- and phoP-knockout mutants were constructed by in-frame deletion and the role of PhoR/phoP on the production of fengycin was determined.  Inactivation of phoR or phoP in  B. subtilis decreased its inhibition ability against Botrytis cinerea growth in vitro compared to the strain NCD-2 wild type.  The lipopeptides were extracted from strain NCD-2 wild type and its mutant strains by hydrochloric acid precipitate, and the lipopeptides from phoR-null mutant or phoP-null mutant almost lost the inhibition ability against B. cinerea growth compared to the lipopeptides from strain NCD-2 wild type.  Fast protein liquid chromatography (FPLC) analysis of the lipopeptides showed that inactivation of phoR or phoP genes reduced the production of fengycin by strain NCD-2.  The fengycin production abilities were compared for bacteria under low-phosphate medium (LPM) and high-phosphate medium (HPM), respectively.  Results indicated that the regulation of fengycin production by the PhoR/PhoP two-component system occurred in LPM but not in HPM.  Reverse transcriptional-PCR confirmed that the fengycin synthetase gene fenC was positively regulated by phoP when cultured in LPM.  All of these characteristics could be partially restored by complementation of intact phoR or phoP gene in the mutant.  These data indicated that the PhoR/PhoP two-component system greatly regulated fengycin production and antifungal ability in B. subtilis NCD-2 mainly under low-phosphate conditions.