First Report of Mango Stem-end Rot Caused by Pestalotiopsis kenyana in Yunnan Province, China.

Stem End Rot (SER) is a devastating post-harvest disease of mango fruits causing severe losses during storage. In 22 July 2023, 31 out of 50 intact mangoes (cv. Sensation) collected from five orchards in Huaping county (26°37'N 101°15') showed typical symptoms of SER after stored for 9 d in room temperature (24-28℃). Initially, small dark brown to black spots appeared around the fruit peduncle, which rapidly expanded through the pulp tissues. The symptomatic mangoes were surface disinfected by 3% NaClO for 30 s after soaking in 75% alcohol for 3 min, and cleaned by sterile water for 3 times. Tissues were cut from the edge of lesions, dried by sterile filter paper, transferred to PDA and cultured at 28 ℃ for 5 d (Tovar-Pedraza et al., 2020). The single-spore isolation method was used to obtain pure culture. Thirty eight isolates presented four distinct kind of morphology on PDA medium. Among them, 11 isolates with same morphology were significantly distinct from common pathogens of SER. The colonies were white and pale yellow on reverse side. Mycelia grew fast and reached the edge of 90 mm Petri dish after cultured for 5d. Pycnidia were black and scattered on the mycelial mats after 15-20 d. Conidia were fusoid, straight to slightly curved, four septa, and brown. Pigmented median cells doliiform, 14.97 - 18.62(16.11 ±0.89)×5.61- 7.28 (6.61±0.51) µm. Apical cell hyaline, subcylindrical; 1-3 tubular transparent apical appendages 12.27 - 16.68 (13.65±3.78)×1.14 - 1.99 (1.59±0.36) µm. Basal cell conical with a truncate base, hyaline, and 1-2 tubulose basal appendages with 2.85 - 7.97 (5.18±1.88)×0.99 - 1.85 (1.38±0.29) µm (n=50). These fungi were described as Pestalotiopsis kenyana. based on morphological characters (Maharachchikumbura et al., 2014) which were different from isolates characterized as other common SER pathogens (Botryosphaeria, Neofusicoccum). Based on morphology, HPSX-4 was selected for further identification. ITS region, tef1-α, ß-tub of HPSX-4 were amplified and sequenced (Xun et al., 2023). The sequences were deposited in GenBank (ITS:OR889126, tef1-α:OR913431, ß-tub: OR913432). The ITS, tef1-α, ß-tub sequence of HPSX-4 showed 100% (525/525)，99.59% (241/242), and 100% (742/742) identity to the P. kenyana CBS442.67 sequences (ITS: NR147549，tef1-α: KM199502, ß-tub: KM199395), respectively. HPSX-4 clustered with P. kenyana CBS 442.67 (type strain) based on maximum likelihood method by MEGA 7.0.21(Minh et al., 2013). Pathogenicity test was performed on 12 healthy mangoes (cv. Golek) by placing mycelial plugs around the peduncle and the middle of the fruit by pin-prick method according to Feng et al.(2023). Sterile PDA were used as control (three mangoes). Every inoculated fruit was incubated at 28°C, 95% ± 3% humidity with three replicates for each treatment. The experiment was repeated three times. Typical symptoms of SER were observed. There were no symptoms in the control group. The strain was reisolated and identified as P. kenyana with the method mentioned above which fulfilled Koch's postulates. This is the first report of P. kenyana causing SER disease on Mangifera indica L.. This study expands our understanding of the pathogen range of mango SER which conducive to prevent and control the SER caused by P. kenyana.

Genomic characterization and phylogenetic analysis of a novel Nairobi sheep disease genogroup Orthonairovirus from ticks, Southeastern China.

The increasing prevalence and transmission of tick-borne diseases, especially those emerging ones, have posed a significant threat to public health. Thus, the discovery of neglected pathogenic agents carried and transmitted by ticks is urgently needed. Using unbiased high-throughput sequencing, a novel Orthonairovirus designated as Meihua Mountain virus (MHMV), was identified in bloodsucking ticks collected from cattle and wild boars in Fujian province, Southeastern China. The full-length genome was determined by RT-PCR and RACE. Genomic architecture of MHMV shares typical features with orthonairoviruses. Phylogenetic analyses suggested that MHMV is clustered into the Nairobi sheep disease (NSD) genogroup of the genus Orthonairovirus and is closely related to the Hazara virus. The RdRp, GPC, and N protein of MHMV shares 62.3%-83.5%, 37.1%-66.1%, and 53.4%-77.3% amino acid identity with other NSD genogroup viruses, respectively, representing a novel species. The overall pooled prevalence of MHMV in ticks was 2.53% (95% CI: 1.62%-3.73%, 22 positives of 134 tick pools), with 7.38% (95% CI: 3.84%-12.59%, 11 positives of 18 pools) in Haemaphysalis hystricis, 6.02% (95% CI: 1.85%-14.22%, four positives of eight pools) in H. formosensis, 25.03% (95% CI: 9.23%-54.59%, six positive of eight pools) in Dermacentor taiwanensis, and 0.16% (95% CI: 0.01%-0.72%, one positive of 100 pools) in Rhipicephalus microplus. This study presented the first report of tick-carried Orthonairovirus in Fujian province and highlighted the broad geographic distribution and high genetic diversity of orthonairoviruses in China.

A Reconfigurable energy-resolving method for a layered edge-on detector.

Currently, most of the x-ray spectral detectors can extract signals in a set number of energy bins, that inevitably reduces the dynamic range and energy resolution of the imaging system. Inspired by the idea of dynamic thresholding, we previously proposed a pixel architecture and an energy-resolving method for layered edge-on detector. However, the complicated energy exchange mechanism of x-rays in the detector that ultimately affects the practical applications of the layered detectors had not been previously considered. In this study, we modify the energy-depositing model of x-ray photons and propose a reconfigurable energy-resolving method to improve the spectral performance of a layered energy integrating detector. We analyze the errors associated with the energy-resolving process and present our numerical simulation results obtained with energy bins and dynamically changed detection layers to demonstrate the utility and reliability of the proposed method.