Water spinach (Ipomoea aquatica Forsk.) is an important leaf vegetable affected by salt stress, however, little is known about its salt adaption mechanism. Here, we integrated physiomics, ionomics, transcriptomics, and metabolomics to analyze the root adaptation response of two water spinach varieties, BG (salt-tolerant) and MF (salt-sensitive), at 150 mM NaCl. The results showed that compared with MF, BG significantly reduced the content of malondialdehyde (MDA) and H2O2, and increased catalase (CAT) activity and proline content. Ionome analysis demonstrated that BG significantly reduced Na+ accumulation and increased K+ level to reduce the toxicity of Na+, compared to MF. Weighted gene co-expression network analysis (WGCNA) revealed that key transcription factors such as HSFA4A, bHLH093, and IDD7, which were only up-regulated in BG. Multi-omics revealed that BG reprogrammed key pathways: starch and sucrose metabolism, as well as galactose metabolism, leading to decreased amylose production and increased sucrose and galactose levels, helping to maintain cellular osmotic balance in response to salt stress. These findings provide insight into transcriptional regulation in response to salt stress, which could advance the genetic enhancement of water spinach.

Excessive N fertilizer application has aggravated soil acidification and loss of N. Although oyster shell powder (OSP) can improve acidic soil, few studies have investigated its ability to retain soil N. Here, the physicochemical properties of latosol after adding OSP and calcined OSP (COSP) and the dynamic leaching patterns of ammonium N (NH₄⁺-N), nitrate N (NO₃⁻-N), and Ca in seepage, were examined through indoor culture and intermittent soil column simulation experiments. Various types of N fertilizer were optimized through the application of 200 mg/kg of N, urea (N 200 mg/kg) was the control treatment (CK), and OSP and COSPs prepared at four calcination temperatures—500, 600, 700, and 800 °C—were added to the latosol for cultivation and leaching experiments. Under various N application conditions, the total leached N from the soil followed ammonium nitrate > ammonium chloride > urea. The OSP and COSPs had a urea adsorption rate of 81.09–91.29%, and the maximum reduction in cumulative soil inorganic N leached was 18.17%. The ability of COSPs to inhibit and control N leaching improved with increasing calcination temperature. Applying OSP and COSPs increased soil pH, soil organic matter, total N, NO₃⁻-N, exchangeable Ca content, and cation exchange capacity. Although all soil enzyme activities related to N transformation decreased, the soil NH₄⁺-N content remained unchanged. The strong adsorption capacities for NH₄⁺-N by OSP and COSPs reduced the inorganic N leaching, mitigating the risk of groundwater contamination.

The LBD family is a plant-specific transcription factor family that plays an important role in a variety of biological processes. However, the function of IbLBD genes in sweet potato remains unclear. In this study, we identified a total of 53 IbLBD genes in sweet potato. Genetic structure showed that most of the IbLBD genes contained only two exons. Following the phylogenetic investigation, the IbLBD gene family was separated into Class I (45 members) and Class II (8) members. Both classes of proteins contained relatively conservative Motif1 and Motif2 domains. The chromosomal locations, gene duplications, promoters, PPI network, and GO annotation of the sweet potato LBD genes were also investigated. Furthermore, gene expression profiling and real-time quantitative PCR analysis showed that the expression of 12 IbLBD genes altered in six separate tissues and under various abiotic stresses. The IbLBD genes belonging to Class I were mostly expressed in the primary root, the pencil root, and the leaves of sweet potatoes, while the genes belonging to Class II were primarily expressed in the various sweet potato roots. The IbLBD genes belonging to Class I were mostly expressed in the primary root, the pencil root, and the leaves of sweet potatoes, while the genes belonging to Class II were primarily expressed in the fibrous root, pencil root, and tuber root.

Hymenocallis littoralis (Jacq.) Salisb. is a common ornamental plant in China. In November 2021, leaf spots were observed on H. littoralis in a public garden in Zhanjiang, Guangdong Province, China (21°17'25″N, 110°18'12″E). Disease incidence was around 60% (n = 100 investigated plants from about 1 ha). Leaf symptoms were round spots with collapse centers, surrounded by yellow halos. Ten symptomatic leaves from 10 plants were sampled. The margins of the samples were cut into 2 mm × 2 mm pieces. The surfaces were disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite for 60 s. Thereafter, the samples were rinsed thrice in sterile water, placed on PDA, and incubated at 28 °C in dark. Pure cultures were obtained by transferring hyphal tips to new PDA plates. Twenty pure cultures were obtained. Single-spore isolation method (Liu et al. 2021) was used to recover the cultures of three isolates (HPC-1, HPC-2, and HPC-3). Colonies of the isolates were dark green with a granular surface, and irregular white (later turning black) edge. Pycnidia were black, globose and 96 -140 μm in diameter. Conidia were single-celled, oval, 7.5 to 13.5 × 4.0 to 7.5 µm (n = 40), with a single apical appendage. Morphological characteristics of the isolates were consistent with the description of Phyllosticta capitalensis (Wikee et al. 2013). Molecular identification was performed using PCR method with MightyAmp DNA Polymerase (Takara-Bio, Dalian, China) (Lu et al. 2012). The internal transcribed spacer (ITS) region, translation elongation factor (TEF1), actin (ACT), and glyceradehyde-3-phosphate dehydrogenase (GAPDH) were amplified using primers ITS1/ITS4, EF1-728F/EF1-986R (Druzhinina et al. 2005), ACT-512F/ACT-783R, and Gpd1-LM/Gpd2-LM (Wikee et al. 2013), respectively. Sequences were deposited in GenBank with accession numbers OM654570 - OM654572 for ITS, OM831376 - OM831378 for tef1-α, OM831346 - OM831348 for ACT, and OM831364 - OM831366 for GAPDH. BLASTn analysis showed that these sequences were 99 to 100% similarity with those of P. capitalensis (ITS, FJ538339; TEF1, FJ538397; ACT, FJ538455; and GAPDH, JF343723). Besides, a phylogenetic tree was generated on the basis of the concatenated data from the sequences of ITS, TEF1, ACT, and GAPDH that nested within the clade containing P. capitalensis (CBS 117118, CPC20510,CPC20267, and CPC18848). From the combination of the morphological and molecular characteristics, the isolates were determined to be P. capitalensis. Pathogenicity testing was performed in a greenhouse with 80% relative humidity at 25 to 30°C. Ten healthy plants of H. littoralis (2 month old with 4 leaves) were grown in pots with one plant in each pot. Three leaves on one plant per isolate were inoculated with three mycelial plugs obtained from 7-day cultures, totaling five plants. Five plants treated with PDA plugs served as the controls. Wet cotton balls were fixed on the leaves with transparent tape for five days to keep it from drying out. The test was conducted three times. After 15 days, similar symptoms were observed in the inoculated leaves as in the garden, whereas control leaves remained asymptomatic and P. capitalensis was successfully re-isolated from the inoculated leaves. Previously, P. capitalensis has been reported to cause leaf spot disease of various host plants around the world (Wikee et al. 2013). However, to our knowledge, this is the first report of leaf spot caused by P. capitalensis on H. littoralis in China. This study provides an important reference for the control of the disease.

Wampee (Clausena lansium [Lour.] Skeels) is a tropical fruit. In July 2022, leaf spot symptom was observed in wampee (cv. JIXIN) in a field ((21°25'N, 110°10'E, about 100 ha ), Guangdong Province, China. Disease incidence was around 70% (n = 100 investigated plants from about 2 ha). Leaf spots were round or irregular with a clear yellow halo around a brown, necrotic lesion. Ten symptomatic leaves from 10 plants were sampled. The margins of the samples were cut into 2 mm × 2 mm pieces. The surfaces were disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite for 60 s. Thereafter, the samples were rinsed thrice in sterile water, placed on potato dextrose agar (PDA), and incubated at 28 °C in the dark for 3 days. Pure cultures were obtained by transferring hyphal tips to new PDA plates. Twenty isolates were obtained. Three representative single-spore isolates (CLCT-1, CLCT-2, and CLCT-3) from the twenty isolates were confirmed to be identical based on morphological characteristics and ITS analysis and used for further study. The colonies on PDA were gray white at first, subsequently turning grayish to dark gray, with numerous black microsclerotia and setae. Conidia were hyaline, aseptate, falcate with pointed ends, and 16.5 to 22.3 × 2.5 to 3.2 μm (n = 30). Morphological characteristics of the isolates were consistent with the description of Colletotrichum truncatum (Schwein.) Andrus & W. D. Moore (Sawant et al. 2012). For molecular identification, the colony PCR method (Lu et al., 2012) was used to amplify the internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and actin (ACT) loci of the isolates using primer pairs ITS1/ITS4, GDF1/GDR1, and ACT-512F/ACT-783R, respectively (Weir et al. 2012). The sequences were submitted to GenBank under accession numbers OP740964 to OP740966 (ITS), OP800837 to OP800839 (GAPDH), and OP800843 to OP800845 (ACT). The sequences of the three isolates were 100% identical (ITS, 547/547 bp; GAPDH, 290/290 bp; and ACT, 266/266 bp) with those of C. truncatum (accession nos. GU227869, GU228261, and GU227967) through BLAST analysis.. In addition, a phylogenetic tree was generated on the basis of the concatenated data from sequences of ITS, GAPDH, and ACT that nested within the clade containing C. truncatum (the type strain CBS 112998) by the maximum likelihood method. From the combination of the morphological and molecular characteristics, the isolates were determined to be C. truncatum. A pathogenicity test was performed in a greenhouse at 24 to 30°C with 80% relative humidity. Wampee plants (cv. JIXIN, n =5, 1-month-old) were inoculated with a spore solution (1 × 105 per mL) until it run-off. Whereas control plants were sprayed with sterile distilled water. Leaf spots were observed on the inoculated plants after 10 days while the control ones remained healthy. The pathogen re-isolated from all the symptomatic leaves was identical to the inoculation isolates in terms of morphology and just ITS analysis, but unsuccessful from the control plants. C. truncatum has also been reported to be the causal agent of anthracnose disease in multiple crops (Diao et al. 2014; Villafana et al. 2018; Stella de et al. 2021), thus, this is the first to report C. truncatum causing leaf spot on C. lansium in China. This study provides an important reference for the control of the disease due to the high host range of C. truncatum.