First Report of Anthracnose Caused by Colletotrichum plurivorum on Passion fruit in Guangxi, China.

Passion fruit (Passiflora edulis Sims.) is popular for its rich taste and nutritional value. The planting area of passion fruit in Guangxi has reached 24,300 ha, with an annual output of 380,000 t (Qian 2023). In March 2023, leave spots on more than half of the plants (cv. Qinmi "NO.9"). Moreover, the incidence of disease on the leaves was approximately 20% in Shabu Town, Qinnan District, Qinzhou City, Guangxi, China (N20˚54'-22˚41', E107˚27'-109˚56'). Leaf diseases were orbicular or irregular in shape, white, whitish-grey, yellowish, or gray in color. When leaves were severely affected, larger blotches were formed with yellow halos. For pathogen isolation, three diseased leaf samples were collected from three gardens, respectively, and 5×5 mm tissues were cut from infected margins, surface-disinfected in 75% ethanol for 15 s, followed by 2% sodium hypochlorite for 1 min, rinsed three times with sterile water, and incubated on PDA at 25°C under 12/12 h light/darkness. After 5 days, ninety cultures were isolated, sixty isolates with similar morphology were retained, and three representative isolates BY-1, BY-2, and BY-4 were randomly selected for further study. On PDA, colonies of the three isolates displayed white or grayish-white. Conidia were single-celled, hyaline, and cylindrical, measuring 17.3±1.5 × 6.3±0.7 µm, 17.8±1.7 × 6.0±0.6 µm, and 16.3±1.4 × 6.4±0.6 µm (n=90) for BY-1, BY-2, and BY-4, respectively. Appressoria were single, brown or black, and irregular in shape, measuring 10.2±1.1×6.5±0.5 µm, 10.5±1.3×7.3±0.6, and 10.9±0.8×7.0±0.8 (n=90) for BY-1, BY-2, and BY-4, respectively. These morphological characteristics were similar to Colletotrichum spp. as previously described (Damm et al. 2019). The isolates were further identified by sequencing the internal transcribed spacer (ITS-ITS1/ITS4), glyceraldehyde-3-phosphate dehydrogenase (GAPDH-GDF/GDR), actin (ACT-512F/783R), partial sequences of the chitin synthase 1 (CHS-1-79F/354R), and beta-tubulin 2 (TUB2-T1/Bt2b) (Zhang et al. 2023). All sequences were deposited in GenBank (ITS: OR741759 to OR741761, GAPDH: OR767654 to OR767656, ACT: OR767657 to OR767659, CHS-1: OR767660 to OR767662, TUB2: OR767651 to OR767653). A phylogenetic tree was built with RAxML version 8.2.10 based on concatenated sequences of ITS-GAPDH-ACT-CHS-1-TUB2. The results revealed that the three isolates clustered with C. plurivorum. To confirm the pathogenicity of the three isolates, attached leaves of healthy 5-month-old passion fruit plants were injured in the middle region with sterile toothpicks and inoculated with 20 µL of spore suspension (106 conidia/mL), and the noninoculated control received 0.05% Tween-20 (6 leaves/plant, 3 plants/treatment). The inoculated plants were kept in a greenhouse at 25°C and covered with plastic bags to maintain high humidity. After 9 days, all inoculated leaves were symptomatic, whereas no symptoms were observed in the control. C. plurivorum was reisolated from infected leaves, confirming Koch's postulates. C. plurivorum has been reported to infect Abelmoschus esculentus (Batista et al. 2020) and Carya illinoinensis in China (Zhang et al. 2023). However, this is the first report of anthracnose caused by C. plurivorum on passion fruit in China. The results can provide a robust basis for scientific prevention and control of anthracnose.

Swamp eel aldehyde reductase is involved in response to nitrosative stress via regulating NO/GSH levels.

Aldehyde reductase (ALR) plays key roles in the detoxification of toxic aldehyde. In this study, the authors cloned the swamp eel ALR gene using rapid amplification of cDNA ends-PCR (RACE-PCR). The recombinant protein (rALR) was expressed in Escherichia coli and purified using a Ni2+ -NTA chelating column. The rALR protein exhibited efficient reductive activity towards several aldehydes, ketones and S-nitrosoglutathione (GSNO). A spot assay suggested that the recombinant E. coli strain expressing rALR showed better resistance to formaldehyde, sodium nitrite and GSNO stress, suggesting that swamp eel ALR is crucial for redox homeostasis in vivo. Consequently, the authors investigated the effect of rALR on the oxidative parameters of the liver in swamp eels challenged with Aeromonas hydrophila. The hepatic glutathione (GSH) content significantly increased, and the hepatic NO content and levels of reactive oxygen species and reactive nitrogen species significantly decreased when rALR was administered. In addition, the mRNA expression of hepatic Alr, HO1 and Nrf2 was significantly upregulated, whereas the expression levels of NF-κB, IL-1ß and NOS1 were significantly downregulated in the rALR-administered group. Collectively, these results suggest that ALR is involved in the response to nitrosative stress by regulating GSH/NO levels in the swamp eel.

Citric acid mitigates soybean meal induced inflammatory response and tight junction disruption by altering TLR signal transduction in the intestine of turbot, Scophthalmus maximus L.

A 12-week feeding trial was conducted to investigate the effect of citric acid on the involvement of TLRs in the soybean meal induced inflammatory response and tight junction disruption in the distal intestine of juvenile turbot (Scophthalmus maximus L.). Four isonitrogenous and isolipidic practical diets were formulated: fish meal-based diet (FM); 40% fish meal protein in FM replaced with soybean meal protein (SBM); SBM + 1.5% citric acid and SBM + 3% citric acid. Compared to the FM, diet SBM significantly increased the gene expression of TLRs (TLR2, TLR3, TLR5b, TLR9, TLR21, TLR22) and MyD88, as well as TLR related molecules (NF-κB, IRF-3, p38 and JNK), which were remarkably reduced by dietary citric acid. Similarly, citric acid supplementation in SBM markedly depressed gene expression of pro-inflammatory cytokines (TNF-α and IFN-γ) and pore-forming tight junction protein Claudin-7, and enhanced gene expression of the anti-inflammatory cytokine TGF-ß1 and TJ proteins related to the decrease in paracellular permeability (Claudin-3, Claudin-4, Occludin, Tricellulin and ZO-1). Compared to the SBM, the concentration of IgM and C4 in serum was significantly reduced by dietary citric acid. In brief, dietary citric acid could synchronously inhibit TLRs-dependent inflammatory response regulated by NF-κB and IRF3, as well as cause TLRs-dependent tight junction disruption modulated by p38 and JNK. Therefore, citric acid could function on mitigating soybean meal induced enteropathy in the distal intestine of juvenile turbot.