First report of powdery mildew caused by Erysiphe euonymicola on wintercreeper (Euonymus fortunei) in China

Wintercreeper (Euonymus fortunei) is an evergreen shrub, a semi climbing plants with very strong vitality. It can tolerate a broad range of environmental conditions varying from full sun to deep shade. So, wintercreeper is a good groundcover plants and tree species of vertical greening. It is widely used in urban greening in China. In May 2021, severe powdery mildew signs were found on wintercreeper plant in a garden of Luohe cities of Henan province, China. Approximately 40% of leaves on a plant were symptomatic, and about 60% of the plants were infected. Powdery mildew colonies appeared as white spots on the upper surface of the leaf and stem of the plants in the initial stage. Later, mycelial growth was amphigenous, thick, forming irregular white patches, effused to cover the entire leaf surface. At last, leaves turned yellow and senescence. One representative voucher specimen was deposited at the herbarium of Shangqiu Normal University (SQNU), Shangqiu, China, under the accession number of EF02. Conidiophores arising terminally from the mother cell, mostly central, erect, straight, 40.7 to 67.7µm (average 49.1µm) 6.1 to 8.5µm (average 7.5µm) (n=30) composed of 3 to 4 cells and produced conidia singly. Conidia were obovoid-ellipsoid, apex rounded, base subtruncate, ends truncate or subtruncate, long 26.1 to 36.4µm (average 30.7µm) and width 9.9 to 16.0µm (average 11.8µm) (n=30). No chasmothecia were observed. The morphological characteristics and measurements were consistent with those of Erysiphe euonymicola (Braun and Cook 2012). The internal transcribed spacer regions of EF02 were amplified using primers ITS1/ITS4, and sequences directly. The obtained sequence of 648 bp was deposited in GenBank (accession no. OM304857). The isolate (EF02) was 99.83% similarity with E. euonymicola on E. fortunei var. radicans (KM361621 from Korea) (Lee et al. 2015), 99.23% with E. euonymicola on E. fortunei (MT510003 from USA), 99.23% with E. euonymicola on E. japonicus (LC270841and LC270834 from Azerbaijan, AB250228 from Japan ). The domains D1 and D2 of the 28S rDNA obtained 619 bp sequences from the powdery mildew of isolate EF02 with primer NL1/NL4, deposited in GenBank (OM302187). A NCBI BLAST search of the EF02 isolate showed 100% similarity with 28S rDNA sequence of E. euonymicola on E. japonicus (AB250230 from Japan) (Limkaisang et al. 2006), and 28S phylogenetic tree analysis EF02 isolate is located in the same branch as E. euonymicola. The pathogenicity was confirmed by gently pressing the infected leaves onto five healthy plants. Five uninoculated plants served as controls. Ten inoculated and non-inoculated plants were placed in different growth chambers with 14-h photoperiod at 22±2°C and 60% of relative humidity. After 11 to 13 days, powdery mildew colonies developed on inoculated plants. Non-inoculated control plants did not show powdery mildew symptoms. The fungus on inoculated leaves was morphologically identical to that first observed in the field. Although E. euonymi-japonici (synonym E. euonymicola) has been recorded on E. japonicus in China (Li et al. 2011), this is the first report of powdery mildew caused by E. euonymicola on E. fortunei in China. It could become a threat to the widespread planting of wintercreeper, Similar report has been in Korea (Lee, C. K., et al. 2015).

Powdery Mildew of tall verbena Caused by Podosphaera xanthii in China

Tall verbena (Verbena bonariensis) is widely used in landscape layout in sparse forests, botanical gardens and villa areas, and it is also a kind of Chinese herbal medicine. The flower and bud use as Chinese herbal medicine causing heat-clearing and detoxification. In August 2019, observed on tall verbena in Shangqiu, Henan Province, China. Symptoms white fungal growth observed on both sides of fresh and mature leaves of tall verbena grown on campus at Shangqiu Normal University. More than 60% plants were infected by this fungus and infected plants were observed to shed leaves early. One representative voucher specimen was deposited at the herbarium of Shangqiu Normal University (SQNU), Shangqiu, China, under the accession number of Vb01. Conidiophores of the fungus contained 5-6cells and measured 102.0-142.9μm (mean 126.2μm, n = 30) long, with foot-cells of conidiophores measured 36.5-46.9μm (mean 42.9μm, n = 30). Conidia produced in chains were variable in shape, ellipsoid to ovoid, and measured 24.8-30.7×12.0-17.9 μm (mean 27.35×15.08μm, n = 50), with a length/width ratio of 1.4 to 2.3. Fibrosin bodies were observed in the conidia. No chasmothecia were found. The morphological characteristics were consistent with the genus Podosphaera. To identify above powdery mildew fungus at species level using molecular markers, the complete ITS region of rDNA from the representative specimen was amplified with universal primer pair ITS1/ITS4 and directly sequenced. The resulting sequence of 567 bp was deposited in GenBank (Accession No. MT864007). A BLAST search of this sequence showed more than 99% sequence identity with P. xanthii isolates (AB046985, AB462804, AB936277 and KM260741) on various hosts (Hirata T, 2000; Meeboon, J., and Takamatsu, S. 2015; Tam L. T. T. 2016). Phylogenetic analysis revealed that ITS sequence from Vb01 isolate was grouped into a clade with P. xanthii s. lat.. A pathogenicity test was conducted through inoculation by gently pressing a diseased leaf onto five healthy leaves of a potted tall verbena. Five non-inoculated seedlings were used as controls. The plants were maintained in a greenhouse at 26 to 28 ℃, and relative humidity of 60 to 65%. Inoculated leaves developed symptoms after nine days, whereas the control plants remained symptomless. The fungus presented on the inoculated plant was morphologically identical to that originally observed on diseased plants, fulfilling Koch's postulates. P. xanthii s. lat. has been reported on several hosts in China (Braun & Cook, 2012). This is the first report of P. xanthii s. lat. on Verbena bonariensis outside of Japan (Meboon, 2015).

A novel basic helix-loop-helix transcription factor, ZjICE2 from Zoysia japonica confers abiotic stress tolerance to transgenic plants via activating the DREB/CBF regulon and enhancing ROS scavenging

ZjICE2 works as a positive regulator in abiotic stress responses and ZjICE2 is a valuable genetic resource to improve abiotic stress tolerance in the molecular breeding program of Zoysia japonica. The basic helix-loop-helix (bHLH) family transcription factors (TFs) play an important role in response to biotic or abiotic stresses in plants. However, the functions of bHLH TFs in Zoysia japonica, one of the warm-season turfgrasses, remain poorly understood. Here, we identified ZjICE2 from Z. japonica, a novel MYC-type bHLH transcription factor that was closely related to ICE homologs in the phylogenetic tree, and its expression was regulated by various abiotic stresses. Transient expression of ZjICE2-GFP in onion epidermal cells revealed that ZjICE2 was a nuclear-localized protein. Also, ZjICE2 bound the MYC cis-element in the promoter of dehydration responsive element binding 1 of Z. japonica (ZjDREB1) using yeast one-hybrid assay. A phenotypic analysis showed that overexpression of the ZjICE2 in Arabidopsis enhanced tolerance to cold, drought, and salt stresses. The transgenic Arabidopsis and Z. japonica accumulated more transcripts of cold-responsive DREB/CBFs and their downstream genes than the wild type (WT) after cold treatment. Furthermore, the transgenic plants exhibited an enhanced Reactive oxygen species (ROS) scavenging ability, which resulted in an efficient maintenance of oxidant-antioxidant homeostasis. In addition, overexpression of the ZjICE2 in Z. japonica displayed intensive cold tolerance with increases in chlorophyll contents and photosynthetic efficiency. Our study suggests that ZjICE2 works as a positive regulator in abiotic stress responses and the ICE-DREB/CBFs response pathway involved in cold stress tolerance is also conserved in Z. japonica. These results provide a valuable genetic resource for the molecular breeding program especially for warm-season grasses as well as other leaf crop plants.

A Clinical Study on the Effect of Injection Sites on Efficacy of Anesthesia and Pulpal Blood Flow in Carious Teeth

This randomized clinical trial evaluated the efficiency of maxillary infiltration anesthesia in carious teeth at two different injection sites and their impact on the laser Doppler recordings of pulpal blood flow (PBF) during a caries excavation procedure. The null hypothesis tested was that there are no differences in the efficiency of anesthesia and PBF reduction between maxillary infiltrations at the two injection sites. One hundred twenty patients were divided into three groups according to the degree of carious lesion of their maxillary left central incisors (moderate caries, deep caries, or no caries). Forty patients in each group randomly received infiltrations over the root apex of maxillary left central incisors (site X) or over the midpoint of the line connecting the root apexes of both maxillary left central and lateral incisors (site Y) using 0.9 mL 2% lidocaine with 1:100,000 adrenaline. Teeth were pulp tested at five-minute intervals after injection except for the period of cavity cutting, which was done 12 minutes after injection. The PBF changes after injection were monitored by laser Doppler flowmetry. The observation period in this study was 60 minutes. Success of anesthesia was defined as no or mild pain on cavity cutting by visual analog scale recordings. Deep caries group showed significantly higher baseline PBF ( p<0.05). All groups showed 100% success of anesthesia and similar duration time ( p>0.05). Subgroups that had the injection at site Y showed significantly less reduction of PBF ( p<0.05). Cavity-cutting procedures increased the amplitude of the PBF around the lowest value after injection. Independent of the cavity depth, carious anterior teeth anesthetized by infiltration further from the apex had significantly less reduction on the pulpal blood flow compared with teeth anesthetized by infiltration at the apex.

First Report of Powdery Mildew Caused by Podosphaera fusca on Herba eupatorii in China

Herba eupatorii, one of the most important Chinese medicinal herbs, belongs to the Asteraceae family. In June 2012, a previously unknown disease, tentatively identified as powdery mildew, was observed on H. eupatorii growing in Shangqiu, in eastern Henan Province, China. Symptoms began as white mycelium partially covering upper leaf surfaces; as the disease progressed, it spread to cover entire leaf surfaces. The infected leaves became yellow and necrotic at advanced stages of infection. Specimens consisting of infected leaves were maintained at the Plant-Microbe Interaction Laboratory at Shangqiu Normal University. Microscopic observations of the morphology of the fungus revealed oval primary conidia measuring 18 to 27 × 15 to 22 μm. A long unbranched germ tube that germinated laterally from the ends of conidia was observed in some samples. Conidiophores were cylindrical, simple unbranched, and composed of a basal cell with a swollen base and three to six barrel-shaped conidia formed in chains, measuring 112 to 180 × 9 to 12 μm. Mycelial appressoria were nipple-shaped. Chasmothecia were not observed in the collected samples. To verify the identity of the fungus, the internal transcribed spacer (ITS) rDNA was amplified with ITS1 and ITS4 primers (3) and sequenced. The sequences were deposited as GenBank Accession No. JX546297. Comparison with sequences in the GenBank database revealed that the ITS sequence was 100% homologous with the sequence of Podosphaera fusca on Calendula officinalis (AB525914) (2) and Syneilesis palmata (AB040349) (1). The ITS sequence analysis verified that the causal agent was P. fusca, which is reported to be a cosmopolitan powdery mildew fungus, parasitic on numerous plant species in the Asteraceae family. Koch's postulates were completed by inoculating healthy H. eupatorii plants with a conidial suspension (prepared in distilled water) of 10⁵ conidia/ml collected from infected plants. Five plants were sprayed until the suspension ran off the leaves, while five additional plants were sprayed with distilled water as a control. Plants were maintained in a climate cell under the following conditions: day, 24°C, 16 h; night, 20°C, 8 h; 85% humidity. After 10 days, inoculated plants developed symptoms similar to those observed in the field, whereas control plants remained healthy. Further examination showed that the inoculated plants were infected by P. fusca. To our knowledge, this is the first report of P. fusca affecting H. eupatorii in China. Because there are no fungicides labeled for use on this plant, the appearance of powdery mildew caused by P. fusca could result in substantial production loss of H. eupatorii. References: (1) T. Hirata et al. Can. J. Bot. 78:1521, 2000. (2) S. Takamatsu et al. Persoonia 24:38, 2010. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.