Blueberries (Vacciniumspp.) have been widely cultivated in China because of their nutritional benefits and economic value. Blueberry stem blight has become one of the most severe diseases influencing blueberry productivity and quality in China. In this study, eight fungal isolates were obtained from twenty stem blight lesions of blueberry collected in Nanping, Fujian province, China. Asexual stage was observed after inducing sporulation, the morphology of which agrees withMacrophominain the black, smooth, hard sclerotia and ellipsoid to obovoid, smooth hyaline conidia with apical sheath. Furthermore, DNA sequences of concatenated ITS,tef1-α,TUB, andACTloci indicated that these isolates belong to a novel fungal species. The distinguishing morphological characteristics, such as the wider conidia and larger conidiomata pycnidial, also support its new status. Thus a novel fungus,Macrophominavaccinii, was described in this study. Pathogenicity tests indicated thatM.vacciniicould cause stem blight of blueberry.

MarR family transcription regulators are ubiquitous among bacteria and archaea. They extensively control multiple cellular processes and elaborately regulate the expression of genes involved in virulence, stress response and antibiotics at translational level. In Xanthomonas campestris pv. campestris, insertional inactivation of MarR family transcription regulator HpaR (XC2827) resulted in significantly decrease in virulence and increase in the production of the extracellular proteases. Here, we reported that the genome of Xcc 8004 encodes nine MarR family transcription regulators. The MarR family transcription regulators, HpaR (XC2827) and XC0449, were heterologous expressed and purified. In vitro MST and Pull-down assay confirmed the physical interaction between HpaR and XC0449. Phenotypical assay determined that deletion of XC0449 resulted in substantial virulence attenuation. In vitro EMSA, in vivo qRT-PCR and GUS activity assay identified that HpaR and XC0449 coordinately act as the transcriptional activator to regulate the expression of the virulence-associated gene XC0705, and eventually control the bacterial virulence and the production of extracellular proteases.

Blueberries (Vaccinium spp.) are largely cultivated in China because of their nutritional benefits and economic value. Blueberry stem blight caused by members of the Botryosphaeriaceae has become one of the most severe diseases affecting blueberry cultivation in China. In this study, we examined the causal agent of blueberry stem blight at commercial greenhouse farms in the suburban area of Beijing, China. In total, 37 isolates of Botryosphaeriaceae were obtained from 100 stem blight samples of blueberry. Twelve of 37 strains were morphologically consistent with the genus Lasiodiplodia, showing ellipsoid to ovoid, one-celled, hyaline conidia that sometimes turned brown, with median septa and longitudinal striations when mature. These 12 strains were identified as belonging to a novel fungal species, Lasiodiplodia vaccinii, based on phylogenetic analysis of the concatenated internal transcribed spacer, RNA polymerase II gene, β-tubulin gene, and translation elongation factor-1α gene sequences as well as morphological characteristics. Pathogenicity tests indicated that L. vaccinii can cause twig blight on blueberry seedlings in the greenhouse. Mycelial growth of L. vaccinii occurred at pH values ranging from 3.0 to 10.0, with an optimum at 6.2, and at temperatures from 15 to 40°C, with an optimum at 30.3°C. Of the seven carbon sources tested, sucrose, fructose, and glucose were all highly efficient in supporting the mycelial growth of L. vaccinii, and xylose was the least effective. Of six nitrogen sources tested, yeast extract and tryptone best promoted mycelial growth of L. vaccinii. The ability of L. vaccinii to grow at high temperatures may help to explain its occurrence in Beijing greenhouses in this study.

A new Botryosphaeria species (B. sinensia) is described and illustrated from China. It is characterized by erumpent, botryose clustered ascostromata, ostiolate ascomata, bitunicate, 8-spored and clavate asci, filiform, rarely branched pseudoparaphyses, hyaline, 1-celled, fusiform ascospores, and a Fusicoccum asexual morph. The hyaline old and discharged conidia with 1–2 septa, broader spermatia formed in the culture and smaller ascostroma readily distinguished it from B. dothidea and other species in Botryosphaeria. The intergenic spacer (ITS) and translation elongation factor 1-alpha (EF1) DNA sequence analysis results also support its separation from other Botryosphaeria species. Its relationships with other species of Botryosphaeria are also discussed based on morphology and DNA sequence comparisons.

A new species of Venturia (V. chinensis) is described and illustrated from the leaves of Lonicera praeflorens collected from Lesser Khingan Mountains, the northeast China. It is characterized by habitat saprobic; ascomata small-sized, solitary or scattered, superficial, subglobose to citriform, wall black, papillate, ostiolate, covered with setae; peridium thin; hamathecium evanescent in mature ascomata; asci 8-spored, bitunicate, fissitunicate, oblong to obclavate, with or without a short, knob-like pedicel; ascospores ellipsoidal, olivaceous pale brown, 1-septate, ascospore wall thin, smooth. Comparisons of V. chinensis with V. lonicerae (another species on Lonicera caerulea) and other species of Venturia lead to the conclusion that collected taxon is new. Its relationships with other species of Venturia are discussed based on morphology and 28S nrDNA and ITS nrDNA sequence comparisons.