Sheath rot disease (SRD) is one of the most devastating diseases of Manchurian wild rice (MWR) (Zizania latifolia Griseb). Pilot experiments in our laboratory have shown that an MWR cultivar "Zhejiao NO.7"exhibits signs of SRD tolerance. To explore the responses of Zhejiao No. 7 to SRD infection, we used a combined transcriptome and metabolome analysis approach. A total of 136 differentially accumulated metabolites (DAMs, 114 up- and 22 down-accumulated in FA compared to CK) were detected. These up-accumulated metabolites were enriched in tryptophan metabolism, amino acid biosynthesis, flavonoids, and phytohormone signaling. Transcriptome sequencing results showed the differential expression of 11,280 genes (DEGs, 5,933 up-, and 5,347 downregulated in FA compared to CK). The genes expressed in tryptophan metabolism, amino acid biosynthesis, phytohormone biosynthesis and signaling, and reactive oxygen species homeostasis confirmed the metabolite results. In addition, genes related to the cell wall, carbohydrate metabolism, and plant-pathogen interaction (especially hypersensitive response) showed changes in expression in response to SRD infection. These results provide a basis for understanding the response mechanisms in MWR to FA attack that can be used for breeding SRD-tolerant MWR.

Zizania latifolia is perennial plant, belonging to the rice tribe (Oryzeae) of the grass family Poaceae (Xu et al. 2020), which is also called jiaobai in China and commonly consumed as a vegetable crop. In 2022, a sheath rot occurred on Z. latifolia plants in Lishui, the Zhejiang Province of China. Symptoms occurred on the leaf sheath and initially showed as water-soaked chlorotic spots, later enlarging to irregular, elliptic, and elongated dark brown necrotic lesions. Later, lesions fused and extended to most of the leaf sheath leading to wilting. Almost 60% of the surveyed Z. latifolia plants in 100 hectare were affected. Diseased samples were collected for pathogen isolation. Symptomatic tissues were taken from the edge of lesions, sterilized for 10 s in 70% ethanol, then 2 min in 1% NaClO, washed three times with sterile distilled water, and placed on potato dextrose agar (PDA) at 26 °C in the dark. Fungal colonies displaying similar morphology were picked and purified by single spore isolation. In total, 8 isolates were obtained from 8 plant samples. When cultured on PDA, fungal colonies were white, gradually turning pale yellow with time. Macroconidia only were produced on Carnation leaf agar (CLA) and were hyaline, slender, falcate with single foot cells, 3 to 5 septate, and measured 29 to 50 μm × 3.75 to 5.0 μm. Chlamydospores were globose to subglobose and measured 6.8 to 16.5 μm. These morphological features were consistent with the description of Fusarium asiaticum (Leslie and Summerell 2006). For molecular identification, the partial translation elongation factor 1 alpha (TEF1-α) gene and RNA polymerase II second largest subunit (RPB2) gene of three representative isolates were amplified and sequenced (O'Donnell et al. 1998). These sequences were identical to each other, and one representative, Z-3-1, was deposited in GenBank (Accession No. OQ129437 and OQ858619, respectively). Analysis of the TEF1-α and RPB2 sequences of Z-3-1 showed that they were 99.85% (688/689) and 100% (945/945) identical to F. asiaticum strain Daya350-3 (KT380124) and MRC 1976 (MH582121), respectively, in NCBI, and had 99.38% and 100% identity to F. asiaticum strain CBS 110257 (AF212451 and JX171573) in Fusarium-ID. A combined phylogenetic tree based on the TEF1-α and RPB2 sequences showed that Z-3-1 was clustered with F. asiaticum using the neighbor-joining algorithm. Pathogenicity testing was conducted by inoculating potted Z. latifolia plants with a 1×105 conidial suspension of isolate Z-3-1, which was prepared by culturing the fungal strain in PDB at 26°C for 4 days in a shaker incubator. Conidial suspensions (1 mL) were dropped onto sheaths of potted Z. latifolia plants with sterile water serving as controls. All inoculated plants were covered with plastic bags and maintained in a humid growth chamber at 26°C with a photoperiod of 16 h. The inoculation experiment was repeated twice with 5 replicates per test. Four days later, the sheaths of potted inoculated plants displayed symptoms similar to those observed in the field. No symptoms were observed on control plants. Fusarium asiaticum was re-isolated specifically from the symptomatic inoculated Z. latifolia plants and confirmed by morphological and molecular methods, thus fulfilling Koch's postulates. Fusarium asiaticum has been reported to be a pathogen of other plants in China, such as Ligusticum (Zhu et al. 2022) and Setaria italica (Kong et al. 2022). To our knowledge, this is the first report of F. asiaticum causing sheath rot of Z. latifolia in China. The identification of the pathogen is the first step in developing appropriate field management strategies for this new disease.

研究5％、10％和15％不同食盐浓度对生腌茭白发酵过程中pH值、总酸、平衡盐度、亚硝酸盐和氨基酸态氮等理化指标及发酵程度、色泽和质构品质的影响.结果表明:腌制食盐浓度10％时,可快速启动发酵,同时抑制发酵过程中其它微生物的生长繁殖,pH值下降至3.42,总酸含量增加至0.38 g/100 g(以乳酸计),平衡盐度和氨基酸态氮分别达到7.05、0.057 g/100 g(以氯化钠计),亚硝酸盐含量低于1 mg/kg(以NaNO2计),腌制14 d～21 d时,茭白的黏聚性、回复性、咀嚼性和胶着性等质构特性最为理想.通过对腌制茭白各项理化指标及品质的分析,建议茭白腌制食盐浓度为10％,腌制时间14 d～21 d.

Zizania latifolia is a perennial plant native to East Asia. The swollen culm of Z. latifolia is a popular vegetable and traditional herbal medicine consumed in China and some other Asian countries. From 2019 to 2021, a sheath rot disease was found in Zhejiang Province of China. Symptoms mainly occurred in the leaf sheath showing as brown necrotic lesions surrounded by yellow halos. The pathogen fungal isolates were isolated from the affected sheaths. Ten representative isolates were selected for morphological and molecular identification by phylogenetic analyses of the translation elongation factor 1-α (TEF1) and the RNA polymerase II subunit beta (RPB2) gene regions. Based on the combined datasets, the fungal isolates were identified as Fusarium andiyazi. Koch’s postulates were confirmed by pathogenicity test, re-isolation and re-identification of the fungal isolates. To the best of our knowledge, this is the first report of sheath rot caused by F. andiyazi in Z. latifolia in China.

茭田水体富营养化和秸秆不合理处置是茭白面源污染形成的主要原因,严重制约茭白产业可持续发展.介绍了茭白水旱间作种植模式的技术操作要点,分析了水旱间作模式在茭田节水、改良土壤、秸秆无害化利用、清洁田园、节本增效等方面的作用,为茭白产业面源污染防治探索新的技术方法.

Aloe vera (L.) Burm f. is a perennial herb belonging to the family liliaceae. It is widely grown for medicinal, cosmetic and vegetable use. In 2018 and 2019, a root rot disease occurred on potted A. vera plants in a nursery in the Hunan Province of China. Symptoms of the disease include water soaking lesions, brown spots on taproot or basal part of the stem. The plants were easy to pull out when the taproot is rotten or necrotic. As the disease progressed upward, leaves in the basal part of stems became red-brown and gradually fell off. In severe cases, the whole plants became rotten and wilted. For isolation purposes, diseased tissues were excised from the lesion margins, surface disinfested with 70% ethanol for 10 s, 0.1% HgCl2 for 2 min, rinsed with sterile water thrice, and then placed on potato dextrose agar (PDA) and incubated at 26°C for 3 days in the dark. When cultured on PDA, fungal strains with similar morphology were consistently isolated and purified by single spore isolation. Colonies showed thick, pink aerial mycelium with a growth rate of 1.3 cm /day. The pigmentation was more intense in the colony center and became pale orange and white at the edge of colony. When cultured on SNA (Spezieller Nährstoffarmer agar), the fungus showed less pigmentation and thinner hyphae. Microconidia were abundantly produced, clavate and oval to kidney shaped, 7.1 to 15.2 μm × 2.5 to 5.1 μm, with 0 to 1 transverse septa. Macroconidia were sickle shaped, slender, slightly incurved in apical cell and foot-shaped in the basal cell, measured 27.9 to 53.2 μm × 2.5 to 3.5 μm, with 3 to 5 septa. These morphological characteristics were similar with those of Fusarium spp. (Booth 1971). For molecular identification, genomic DNA of the fungus was extracted by cetyl trimethyl ammonium bromide method. A portion of EF-1α (translation elongation factor 1-α) and RPB1 (the largest subunit of RNA polymerase) genes were amplified and directly sequenced using the EF-1/EF-2 and Fa/G2R primers (O'Donnell et al. 2010). The EF-1α and RPB1 were deposited in the GenBank with accession numbers MT755386 and MT755387. The EF-1α and RPB1 had 97.14% (ID FD_01334) and 99.62% identity (FD_03853), respectively, to F. xylarioides strains in the Fusarium-ID database (Geiser et al. 2004). In addition, the EF1-a showed 96.825% identity to the F. lateritium CBS 119871(AM295281) (a synonym of F. xylarioides), and the RPB1 showed 99.623% identity to the F. xylarioides NRRL 25486 (JX171517.1). Accordingly, the fungus was putatively identified to be F. xylarioides. For pathogenicity assay, A.vera seedlings were pot planted using sterilized nursery soil and inoculated with conidia suspension (1 × 105 conidia/ml), which were eluted from 7-day-old PDA cultures with sterilized water, according to the method described previously (Vakalounakis et al. 2015). The collar of each potted plant was poured with 20 ml of conidia suspensions. Plants mock inoculated with sterile water were used as control. All the inoculated plants were placed in a growth chamber at 25°C under 12/12 h light/dark cycle. The inoculation assays were carried out twice, with each one had three replicated plants. After 30 days, rot symptoms seen from the roots and basal part of stems were observed on the inoculated plants, but no visible symptoms were observed on control plants. The fungus was re-isolated from the inoculated plants and identified to be F. xylarioides by morphological and molecular characteristics, thus confirming Koch's postulates. As we know, many Fusarium species have been reported to cause root and stem rot disease in A.vera such as the F. oxysporum (Ji et al. 2007) and F. solani (Vakalounakis et al. 2015). However, to the best of our knowledge, this is the first report of F. xylarioides causing root and stem rot disease of A.vera in China. The identification of the pathogen fungus might provide a foundation for taking appropriate control strategies to this disease.

Acidovorax citrulli can be divided into two genetic groups: group I and group II based primarily on pulsed-field gel electrophoresis (PFGE) and multilocus sequence classification (MLST). To distinguish more rapidly between strains of the two groups, a pair of specific primer for specific polymerase chain reaction (PCR) that can identify group II strains was designed based on the pilL gene of a group II strain, AAC00-1. PCR results showed that a 332-bp band was generated for 51 of 52 group II strains whereas only three of 93 group I strains were positive, largely consisting with previous studies of A.citrulli classification. Results of PCR showed the primers were able to detect group II strains of A.citrulli and distinguish between strains of groups I and II rapidly and accurately.