Action mechanism of the potential biocontrol agent Brevibacillus laterosporus SN19-1 against Xanthomonas oryzae pv. oryzae causing rice bacterial leaf blight.

The causal agent of rice bacterial leaf blight (BLB) is Xanthomonas oryzae pv. oryzae (Xoo), which causes serious damage to rice, leading to yield reduction or even crop failure. Brevibacillus laterosporus SN19-1 is a biocontrol strain obtained by long-term screening in our laboratory, which has a good antagonistic effect on a variety of plant pathogenic bacteria. In this study, we investigated the efficacy and bacterial inhibition of B. laterosporus SN19-1 against BLB to lay the theoretical foundation and research technology for the development of SN19-1 as a biopesticide of BLB. It was found that SN19-1 has the ability to fix nitrogen, detoxify organic phosphorus, and produce cellulase, protease, and siderophores, as well as IAA. In a greenhouse pot experiment, the control efficiency of SN19-1 against BLB was as high as 90.92%. Further investigation of the inhibitory mechanism of SN19-1 on Xoo found that the biofilm formation ability of Xoo was inhibited and the pathogenicity was weakened after the action of SN19-1 sterile supernatant on Xoo. The activities of enzymes related to respiration and the energy metabolism of Xoo were significantly inhibited, while the level of intracellular reactive oxygen species was greatly increased. Scanning electron microscopy observations showed folds on the surface of Xoo. A significant increase in cell membrane permeability and outer membrane permeability and a decrease in cell membrane fluidity resulted in the extravasation of intracellular substances and cell death. The results of this study highlight the role of B. laterosporus SN19-1 against the pathogen of BLB and help elucidate the underlying molecular mechanisms.

First Report of Diaporthe pseudophoenicicola causing Leaf Blight on Pecan in China.

Pecan (Carya illinoinensis) is one of the important economic forest crops widely cultivated in Jiangsu Provinces, China. From August to September in both 2021 and 2022, a foliar blight was observed in 7-ha and 6-ha pecan orchards in Changzhou (31°58'9.6″ N, 119°48'33.84″ E), and Jurong (31°52'15.46″ N, 119°9'24.62″ E), Jiangsu Province. The disease severity was about 32% with 8% incidence on 120 surveyed trees of the two orchards. Typical symptoms were lesions with a dark-brown color, which later became brown. We collected eighteen pecan leaves with typical symptoms in the surveyed pecan orchards and took them back to the laboratory for identification. Small fragments (approximately 9 mm2) from the necrotic borders of infected leaves were surfaced sterilized, plated on potato dextrose agar (PDA) and then incubated in darkness at 25°C. Pure cultures were obtained by single-spore culture. Thirty-three isolates with similar characteristics were obtained from the infected leaves (isolation frequency 85%), and the colonies surface on PDA was ochreous with patchs of olivaceous-yellow and sparse aerial mycelium. Observing from the back of the plate, the colonies were cream-yellow. Two types of single-cell conidia were produced on PDA. Alpha-conidia were 7.4 (range, 5.9 to 8.8) × 2.1 (range, 1.6 to 2.8) µm (n = 100), aseptate, smooth, fusiform, straight and tapering towards both ends. Beta-conidia were 25.1 (range, 19.1 to 36.2) × 1.3 (range, 1.0 to 2) µm (n = 100), filiform, hyaline, aseptate and curved at one end. The morphological features of these isolates agreed with those of Diaporthe sp. (Gomes et al. 2013; Gao et al. 2017). To further identify the isolates, the regions of internal transcribed spacer (ITS, OR214967 to OR214969), calmodulin (CAL, OR228558 to OR228560), translation elongation factor 1-α (EF1a, OR228561 to OR228563), histone H3 (HIS, OR228564 to OR228566), and beta-tubulin 2 (TUB2, OR228567 to OR228569) were amplified and sequenced from genomic DNA for the three representative isolates (LSM1, LSM2 and LSM3), respectively (Gomes et al. 2013). Multilocus phylogenetic analysis revealed that the three isolates and D. pseudophoenicicola were clustered in the same clade. Based on the results of morphological and molecular analysis, these isolates were identified as D. pseudophoenicicola. The pathogenicity of three isolates were tested on leaves of pecan seedlings. The conidial suspension (1 × 105 conidia/ml) of each isolate was sprayed evenly on the surface of leaves of three healthy seedlings. Sterilized distilled water was used for negative controls. Finally, all inoculated plants were kept in a greenhouse at 28°C under 100% relative humidity. Two weeks after inoculation, the inoculated plants developed symptoms similar to those of the original diseased plants, while controls remained asymptomatic. D. pseudophoenicicola were re-isolated from from inoculated plants. The pathogenicity experiment was repeated three times. Previously, D. pseudophoenicicola has been reported to cause stem-end browning disease in ripe mango (Takushi et al. 2016; Xu et al 2022). To our knowledge, this is the first report of D. pseudophoenicicola causing leaf blight on pecan . This study provides important information for developing effective pecan disease management practices.

First Report of Scab Disease Caused by Venturia effusa on Pecan in Anhui Province of China.

Pecan (Carya illinoinensis) is a world-famous nut tree which widely cultivated in China. Quanjiao County, located in Anhui province, is reputed to be the capital of pecan production in China. Since 2019, typical scab symptoms were observed on most pecan cultivars in orchards located in the regions of Quanjiao (32°5'7.08″ N, 118°16'2.91″ E). In April, dark brown to black lesions of scab could be observed on both the abaxial and adaxial surface of the lamina, and were often associated with the veins or midrib. In July, small, brownish, and circular lesions ranging from 1 to 2 mm in diameter were observed at the end of stems and shoulder of the fruit. In the surveyed orchards, disease incidence on the leaves reached more than 35%. While, according to the number of infected nut clusters, disease incidence ranged from 40 to 60% on the infected fruits. Using a sterilized scalpel, conidia were scraped from the surface of a single lesion from the infected leaves or fruits, and a dilute spore suspension was prepared in sterile distilled water, of which 100 microliters was spread on 1% water-agar plate (Bock et al. 2014). The conidia were incubated at 25°C for 48 h under fluorescent lights with a 12-hphotoperiod. Single germinated conidia were selected and transferred into potato dextrose agar (PDA) plate to obtain monospore isolates. From 2019 to 2020, more than 20 isolates were obtained from the infected leaves and fruits. Incubated at 24°C for 6 weeks in darkness on PDA, the colonies were gray-black with circular morphology and floccose texture, which were consistent with the characteristics of Venturia effusa described previously (Gottwald 1982). The conidia were pyriform to ellipsoid, zero to one septate, smooth, attenuated towards apex and base, base truncate, pale brown and 10.08 to 18.14 × 4.86 to 9.56 µm (n = 50) in size. To further identify the isolates, the regions of internal transcribed spacer (ITS), beta-tubulin 2 (TUB2) and translation elongation factor 1 alpha (EF1-a) were amplified and sequenced from genomic DNA for the three representative isolates (AH-81 and AH-82 from the infected leaves, and AH-41 from the infected fruits), respectively (White et al. 1990; Young et al. 2018; Bensch et al. 2006). Sequences of them were deposited in GenBank under nos. OP199056 to OP199058 (ITS), OP566581 to OP566583 (TUB2) and OP566578 to OP566580 (EF1-a). Multilocus phylogenetic analysis revealed that three isolates and V. effusa were clustered in the same clade, indicating high genetic similarity between these organisms. Their morphological and molecular characteristics were consistent with those for V. effusa. The pathogenicity of three isolates were tested on two-year-old container-grown pecan seedlings, which were grown in the nursery. The conidial suspension with a concentration of 5 × 105 conidia/ml was sprayed evenly on the surface of leaves of a healthy pecan seedling, and each isolate inoculated four pecan seedlings. The pathogenicity experiment was repeated three times. The plants inoculated with sterile water were used a negative control. The inoculated plants were enclosed in plastic bags for 2 days, and kept in the nursery greenhouse. Four weeks after inoculation, a similar symptom of scab was observed on leaves of cultivar Mahan, and V. effusa was isolated again from inoculated leaves with the frequency of 100% by the single-spore isolation, whereas no symptoms were observed on the control plants. To our knowledge, this is the first report of V. effusa as a scab pathogen on pecan in Anhui Province of China and underscores the need for monitoring this disease and developing disease control strategies to prevent severe reduction in the value of fruit. References: Bensch, K., et al. 2006. Studies in Mycology, 55(1): 299-305. Bock, C. H., et al. 2014. Forest Pathology, 44(4): 266-275. Gottwald, T. R. 1982. Taxonomy of the pecan scab fungus Cladosporium caryigenum. Mycologia. 74 (3), 382-390. White, T. T., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Application. Academic Press, San Diego, CA. Young, C. A., et al. 2018. Phytopathology, 108(7): 837-846. The author(s) declare no conflict of interest. Keywords: Venturia effusa, Scab, Pecan, Identification †Indicates the corresponding author.Y. Q. Zhao; zhaoyuqiang123@126.com.

First Report of Colletotrichum siamense causing Anthracnose on Pecan in China.

Pecan (Carya illinoinensis) is one of the important economic forest crops which has been widely cultivated in Anhui and Jiangsu Provinces, China. Since 2019, symptoms resembling anthracnose disease had been observed in 5-ha and 6.6-ha pecan orchards in Quanjiao ( 32°5'7.08″ N, 118°16'2.91″ E), Anhui Province, and Jintan (31°42'23.84″ N, 119°21'22.90″ E), Jiangsu Province. The disease severity was about 20 to 30% with 5 to 15% (about 500 trees) incidence. In May, symptoms of leaf initially appeared as small dark lesions, which gradually developed to irregular-shaped, sunken lesions (Figure S1, A). From August to October, similar symptoms were also observed on the fruits. Infected fruits appeared irregularly, dark and depressed necrotic lesions on which orange spore masses could be occasionally observed (Figure S1, B). As the disease progressed, the necrotic lesions gradually expanded and merged, resulting in abscission of the fruits. Small fragments (4 × 4 mm) from the necrotic borders of infected fruits or leaves were surfaced sterilized, plated on potato dextrose agar (PDA) and then incubated in darkness at 25°C for 3 days. Pure cultures were obtained from individual conidia by recovering single spores. On the PDA plate, the colonies surface was white and cottony. Observing from the back of the plate, the colonies were pale yellow at the centre and pale white at the margin (Figure S1, E). Spores were produced over PDA plates after 7 days growth. Conidia were hyaline, smooth walls, aseptate, guttulate, cylindrical with rounded ends with 14.8 to 17.5 × 3.3 to 4.7 µm (mean 16.5 × 4.1µm, n = 50) in size (Figure S1, F). These morphological characteristics were similar to those of the species of Colletotrichum siamense (Prihastuti et al. 2009; Weir et al. 2012; Fu et al. 2019). Thirty-two isolates Colletotrichum sp. were obtained from the infected leaves and fruits (isolation frequency about 80%). To further identify the isolates, the regions of internal transcribed spacer (ITS), calmodulin (CAL), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), chitin synthase (CHSI), and beta-tubulin 2 (TUB2) were amplified and sequenced from genomic DNA for the four representative isolates (JS1 and AH1 from infected fruits; JS2 and AH2 from infected leaves), respectively (Weir et al. 2012). Sequences of them were deposited in GenBank under nos. OP389224 to OP389227 (ITS), OP413765 to OP413768 (CAL), OP413761 to OP413764 (ACT), OP413773 to OP413776 (GAPDH), OP413769 to OP413772 (CHSI), and OP413777 to OP413780 (TUB2). Blast analysis showed these sequences shared high identity with C. siamense (100% with ITS, CAL, CHSI, and TUB2; 98.94% with ACT; 98.19% with GAPDH). Multilocus phylogenetic analysis revealed that the four isolates and C. siamense were clustered in the same clade (Figure S2). Based on the results of morphological and molecular analysis, these isolates were identified as C. siamense. The pathogenicity of four isolates was tested on two-year-old container-grown pecan seedlings, which were grown in the nursery. The conidial suspension with a concentration of 5 × 106 conidia/ml was sprayed evenly on the surface of leaves of a healthy seedling, and each isolate inoculated three pecan seedlings. The pathogenicity experiment was repeated three times. For negative controls, pecan seedlings were sprayed with sterilized distilled water. Finally, all inoculated plants were kept in a greenhouse at 25°C under a 16 h/8 h photoperiod and 70% relative humidity. Three weeks after inoculation, the inoculated plants showed symptoms similar to those of the original diseased plants (Figure S1, C), while controls remained asymptomatic (Figure S1, D). Cultures were re-isolated from the infected leaves and were identified as C. siamense by both morphological characteristics and DNA sequence analysis. Previously, C. nymphaeae, C. siamense, C. fructicola and C. viniferum have been reported to cause anthracnose of Pecan worldwide (Zhang et al. 2019; Oh et al. 2021; Poletto et al. 2019; Zhao et al. 2022 ). To our knowledge, this is the first report of C. siamense causing anthracnose on pecan in China. The identification of this pathogen will facilitate the development of strategies for managing the disease in China. References: Oh, J. Y., et al. 2021. Plant disease. 105(10):3296. Poletto, T., et al. 2019. Plant disease. 103(12):3277. Prihastuti, H., et al. 2009. Fungal Divers. 39:89. Fu, M., et al. 2019. Persoonia-Molecular Phylogeny and Evolution of Fungi. 42(1):1-35. Weir, B. S., et al. 2012. Studies in Mycology. 73:115. Zhao, et al. 2022, Acta Phytopathologica Sinica, doi:10.13926/j.cnki.apps.000648 Zhang, Y. B., et al. 2019. Plant disease. 103(6):1432. The author(s) declare no conflict of interest. Keywords: Colletotrichum siamense, Anthracnose, Carya illinoinensis, Pathogenicity †Indicates the corresponding author. Y. Q. Zhao; zhaoyuqiang123@126.com.

Enzymology, Histological and Ultrastructural Effects of Ar-Turmerone on Culex pipiens pallens Larvae.

Our previous article demonstrated that ar-turmerone ((6S)-2-methyl-6-(4-methylphenyl)-2-hepten-4-one) extracted from Curcuma longa L. has a significant larvicidal activity against the fourth instar larvae of Culex pipiens pallens. To reveal the effects of ar-turmerone on C. pipiens pallens larvae, light microscopy and transmission electron microscopy were used to observe the histological and ultrastructure changes in muscle and digestive tissues of fourth instar larvae. It was also revealed by detecting the activity of the acetylcholinesterase (AChE) enzyme and three detoxifying enzymes, including carboxylesterase (CarE), glutathione-S-transferase (GST) and Cytochrome P450 monooxidases (P450). The observation under the light microscope showed that the larvae displayed a disruption of myofibril in ventral muscle cells, the disappearance of nucleolus in the malpighian tubule cells, and the exfoliation of the brush border in midgut epithelial cells, 24 h after treatment. The observation under the transmission electron microscope displayed disorganized Z-lines in the ventral muscle cells, and dissolved membrane of mitochondria, nuclear and endoplasmic reticulum in abdominal cells. The enzymatic activity results showed that ar-turmerone significantly increased the level of detoxifying enzymes, while the activity of AChE was not obviously affected. All the results suggest that the larvicidal mechanism of ar-turmerone is estimated to be stomach poison and the active sites might be the muscle and digestive tissues, and the mode of action of ar-turmerone may be unrelated to AChE.

Work-family conflict and job satisfaction: emotional intelligence as a moderator.

The negative impact of work-family conflict (WFC) on employees' well-being and job-related outcomes has attracted much research attention recently. A major gap in the literature is which factors could potentially buffer its negative effect on employees. The present study examined the moderating effect of emotional intelligence on the relationship between WFC and job satisfaction in a sample of 212 Chinese high school teachers. On the basis of conservation of resource theory, we hypothesized that emotional intelligence would weaken the negative effect of family-to-work and work-to-family interference on job satisfaction. Results suggested that WFC (work-to-family interference and family-to-work interference) was negatively related to job satisfaction and that emotional intelligence weakened the effect of WFC on job satisfaction. These findings provide implications for theories on WFC and emotional intelligence, such as conservation of resource theory. The current study also provides a test of these theories in Chinese culture to support the generalizability of theories developed in previous research. Practical implications for reducing the negative influence of WFC on employees' job satisfaction are also provided, such as the potential value of emotional intelligence for the training and development of employees in teaching professions.

Improved phytoremediation of oilseed rape (Brassica napus) by Trichoderma mutant constructed by restriction enzyme-mediated integration (REMI) in cadmium polluted soil.

In this study, oilseed rape (Brassica napus) was exploited in remediation of Cd-contaminated soil in combination of Trichodermakoningii. To improve its phytoextracting efficiency, restriction enzyme-mediated integration was used to construct Trichoderma mutants with higher Cd resistance. Of 200 mutants, 10 mutants were shown with higher Cd tolerance and enhanced ability of removing Cd from growth medium. In pot experiment, mutant P6 significantly alleviated the negative impacts of Cd on oilseed rape growth, and improved the Cd uptake ability of oilseed rape shoot in Cd contaminated soil (p<0.05). Based on the dry weight, the amounts of Cd in shoots of mutant P6 treated oilseed rape were increased by 23% and 38% per pot compared with wild type Trichoderma treatment; 53% and 107% against non-inoculated treatment, respectively, at 20 and 50mgCdkg(-1) soil. The results suggested the Trichoderma mutant-oilseed rape symbiosis system could be used in remediation of soil contaminated with heavy metal Cd.