Leaf Edge Research Articles

First Report of Botrytis deweyae Causing Gray mold on Polygonatum cyrtonema in China.

Polygonatum cyrtonema Hua., is one of the cultivated varieties of Polygonatum sibiricum Redouté., which also an important cash crop in China (Chen, J., et al. 2021). From 2021 to 2022, symptoms resembling gray mold were observed on P. cyrtonema leaves with 30 to 45% disease incidence in Wanzhou District (30°38'1″N, 108°42'27″E) of Chongqing. The symptoms started to occur from April to June and more than 39% of leaves were infected from July to September. Symptoms started as irregular brown spots and progressed to the leaf edges or tips and stems. In dry conditions, the infected tissue appeared dry and thin, light brown in color, and became dry and cracked in the later stages of disease development. When the relative humidity was high, infected leaves developed water-soaked decay with a brown stripe around the lesion, and a gray mold layer appeared. To identify the causal agent, 8 typical diseased leaves were collected, leaf tissues were chopped into small pieces (3×5 mm), surface sterilized for 1 min in 70% ethanol and 5 minutes in 3% sodium hypochlorite, rinsed three times using sterile water, placed onto potato dextrose agar (PDA) amended with streptomycin sulfate (50 μg/ml) and incubated at 25°C for 3 days in dark conditions. Then 6 colonies (3.5 to 4 cm diameter) with similar morphology were transferred onto new plates. In the initial stage of growth of isolates, all hyphal colonies were white, dense, and clustered, and dispersed in all directions. After 21 days, brown to black-colored sclerotia (2.3 to 5.8 mm diameter) were observed embedded on the bottom of the medium. The six colonies were confirmed to be Botrytis sp. based on the morphological characteristics. The conidia were attached in branches on the conidiophores in grape-like clusters. Conidiophores were straight and 150 to 500 μm in length, and the conidia were single-celled, long ellipsoidal, or oval-like, with no septa and 7.5 to 20 × 3.5 to 14 μm (n=50). For molecular identification, DNA was extracted from representative strains 4-2 and 1-5. The internal transcribed spacer (ITS) region and sequences from the RNA polymerase II second largest subunit (RPB2), and the heat-shock protein 60 (HSP60) genes were amplified using primers ITS1/ITS4, RPB2for/RPB2rev, and HSP60for/HSP60rev, respectively (White T.J., et al.1990; Staats, M., et al. 2005). The sequences were deposited in GenBank: 4-2 [ITS; OM655229: RPB2; OM960678: HSP60; OM960679] and 1-5 [ITS; OQ160236: RPB2; OQ164790: HSP60; OQ164791]. These sequences from isolates 4-2 and 1-5 had 100% similarity to the B. deweyae CBS 134649/ MK-2013 [ITS; HG799538.1: RPB2; HG799518.1: HSP60; HG799519.1] ex-type sequences, and phylogenetic analyses based on multi-locus alignment demonstrated strains 4-2 and 1-5 as B. deweyae. Isolate 4-2 was used to verify whether B. deweyae can cause gray mold on P. cyrtonema, by conducting Koch's postulates experiments (Gradmann, C., 2014). The leaves of P. cyrtonema planted in pots were washed with sterile water, and brushed with 10 mL of hyphal tissue in 55% glycerin. Leaves of another plant were brushed with 10 mL 55% glycerin as control, and Kochs' postulates experiments were conducted three times. Inoculated plants were kept in a chamber with 80% relative humidity at 20 ± 1°C. Seven days after inoculation, disease symptoms similar to those in the field were observed on leaves, whereas control plants remained asymptomatic. The fungus was reisolated from inoculated plants and identified as B. deweyae based on multi-locus phylogenetic analysis. To our knowledge, B. deweyae is mostly found on Hemerocallis, is likely to be an important contributor to the development of 'spring sickness' symptoms (Grant-Downton, R.T., et al. 2014.), and this is the first report of B. deweyae causing gray mold on P. cyrtonema in China. Although B. deweyae has a limited host range, it might also become a potential threat to P. cyrtonema. This work will provide a basis for the prevention and treatment of the disease in the future.

Fig Rust Caused by Cerotelium fi ci: Past, Present and Future

Fig rust is one of the serious fungal diseases caused by Cerotelium fi ci which causes great loss to the overall growth and yield of the plant. This disease is generally characterized by pale reddish-brown to reddish-brown angular leaf spots, typically found on the adaxial surfaces of the leaves, whereas the corresponding abaxial surface of the same leaves was covered with a lot of orange rust pustules. With the progression of this rust disease, angular spots fused to form necrotic patches whereas, leaf edges curled upward. Premature abscission of leaves takes place, leaving bare branches and unripe fruits. This disease showed its global distribution in tropical and subtropical areas, however, the highest distribution was found in the African continent (18 countries) followed by Asia (14 countries), North & South America (10 countries each), Europe (8 countries) and 7 countries in the Oceanian continent. Apart from the rust pathogen Cerotelium fi ci, the Phakospora nishidana was also reported to cause fi g rust which has created confusion on the identity of C. fi ci as a fi g rust pathogen. This suggests a need to re-examine all specimens of fi g rust at the global scale, based on morphological and modern DNAbased methods so that the taxonomic ambiguities on fi g rust pathogens can be resolved and suitable control methods can be implemented to avoid serious crop and yield loss.

Inventarisasi Tumbuhan Famili Myrtaceae Di Kampung Andir, Rt.01/Rw.08, Desa Rancamulya, Sumedang

Myrtaceae is one of the largest families, numbering 5500 species. General characteristics of this family include taproots, woody stems, thin skin, shrubs, tannins, single leaves, and flat leaf edges. The fruit is in the form of tubers, tops, capsules and drupes. The purpose of this study was to determine the types of plants belonging to the Myrtaceae and to determine the morphology and distribution of the Myrtaceae family. The research was conducted on June 12 2023 in Andir Village, RT.01 / RW.08, Rancamulya Village, Sumedang Utara District, Sumedang Regency. The method used is the method of exploration and observation by exploring the research location while observing the surrounding plants. The species results obtained included Syzygium aqueum totaling 4 individuals, Syzygium polyanthum totaling 6 individuals, Syzygium myrtifolium Walp totaling 176 individuals and Psidium guajava L totaling 7 individuals.

Metabolomics-based study on the changes of endogenous metabolites during adventitious bud formation from leaf margin of Bryophyllum pinnatum (Lam.) Oken

Bryophyllum pinnatum (Lam.) Oken is an ornamental and ethno-medicine plant, which can grow a circle of adventitious bud around the leaf margin. The dynamic change of metabolites during the development of B. pinnatum remains poorly understood. Here, leaves from B. pinnatum at four developmental stages were sampled based on morphological characteristics. A non-targeted metabolomics approach was used to evaluate the changes of endogenous metabolites during adventitious bud formation in B. pinnatum. The results showed that differential metabolites were mainly enriched in sphingolipid metabolism, flavone and flavonol biosynthesis, phenylalanine metabolism, and tricarboxylic acid cycle pathway. The metabolites assigned to amino acids, flavonoids, sphingolipids, and the plant hormone jasmonic acid decreased from period Ⅰ to Ⅱ, and then increased from period Ⅲ to Ⅳ with the emergence of adventitious bud (period Ⅲ). While the metabolites related to the tricarboxylic acid cycle showed a trend of first increasing and then decreasing during the four observation periods. Depending on the metabolite changes, leaves may provide conditions similar to in vitro culture for adventitious bud to occur, thus enabling adventitious bud to grow at the leaf edge. Our results provide a basis for illustrating the regulatory mechanisms of adventitious bud in B. pinnatum.

Two feedback mechanisms involved in the control of leaf fragment size in leaf-cutting ants.

Polymorphic leaf-cutting ants harvest leaf fragments that correlate in size with the workers' body size. When cutting, workers anchor their hind legs on the leaf edge and rotate, removing approximately semicircular fragments. Workers show behavioural plasticity and modify their leg extension while holding onto the leaf edge depending on, for instance, leaf toughness, cutting smaller fragments out of tough leaves. What sensory information workers use to control the cutting trajectory remains unknown. We investigated whether sensory information from both the leg contact with the leaf edge and from head movements underlies fragment size determination. In the laboratory, we recorded Atta sexdens workers cutting standardised ®Parafilm pseudoleaves of different thickness, and quantified cutting behaviour and body reach, i.e. the distance between the mandible and the anchored hind leg tarsus. Experimentally preventing contact with the leaf edge resulted in smaller fragments, evincing that workers control the cutting trajectory using information from the contact of the hind legs with the leaf edge. However, ants were able to cut fragments even when contact of all six legs with the edge was prevented, indicating the use of additional sensory information. Ablation of mechanosensory hairs at the neck joint alone did not influence fragment size determination, yet simultaneously preventing sensory feedback from both mechanosensory hairs and edge contact led to a loss of control over the cutting trajectory. Leaf-cutting ants, therefore, control their cutting trajectory using sensory information from both the leg contact with the leaf edge and the lateral bending of the head.

How leaf-cutting ants gauge leaf portion size

They might not be able to leap tall buildings with a single bound, but leaf-cutting ants are insect superheroes, capable of carrying leaf pieces up to six times their body mass to cultivate fungus in their borrows. But how do the charismatic creatures determine the size of the fragments they carve with their mandibles? Do they use their bodies as a simple ruler, or do they use information about the position of their bodies to adjust how far they cut, adapting to the thickness of a leaf while dismembering it? Knowing that the insects alter the trajectory of a cut when sculpting ®Parafilm of different thicknesses, Flavio Roces from the University of Würzburg, Germany, decided to find out how the ants govern the size of the portions they trim. But first he, Daniela Römer and Rebecca Exl (also from University of Würzburg) needed to get to grips with how the insects snip out regular leaf fragments.Exl fashioned fake leaves from ®Parafilm – one layer for thin leaves (0.13 mm), three for thick leaves (0.38 mm) – rubbed them with crushed bramble leaves or rose oil to make them more appealing to the ants and installed them in the foraging area of a lab-based Atta sexdens ant colony. As soon as an ant climbed aboard, Exl retrieved the pseudoleaf and positioned it in front of a camera to record the ant's manoeuvres.Initially, the ant lay along the edge of the leaf, with the hind and middle leg on the side nearest the edge gripping the ®Parafilm. Then, it snipped upward, gradually rotating its body until upright as it cut in an arc, attaching the second hind limb when its body was almost vertical. As the ant continued cutting, it rotated further, eventually releasing the first hind limb from the leaf edge while still holding on with the second hind limb, until it severed the chunk by cutting through the leaf edge after swivelling the body through 180 deg. And when Exl compared the ants’ posture as they cut through thick and thin leaves, she realised that they adapted their technique, crouching their legs to reduce their reach to cut smaller elliptically shaped fragments when provided with thick leaves.But how were the ants controlling the size of the fragments they incised? Could knowledge about the position of their hind legs gripping the leaf edge guide their cutting trajectory? This time, Exl waited until each ant was halfway through a cut before gently inserting a piece of paper between the ant and the fake leaf to release its grip as it continued snipping. Without knowledge of the position of their legs relative to the leaf edge, some of the ants cut smaller elliptical portions. They were using information provided by their hind legs gripping the leaf edge to guide the trajectory of their cut. However, some ants were still able to cut similarly sized fragments. Were they using some other sensory information to guide their trajectory? Could hairs at the front of the neck, which detect the position of the head, contribute to their sense of cutting direction?Exl cautiously shaved off these hairs and allowed the ants to cut a ®Parafilm leaf while gently detaching the insect's limbs from the edge with the paper guard, and this time the ants completely lost track of direction, producing randomly shaped fragments that were nothing like the elliptical pieces they had cut previously. Leaf-cutting ants depend on knowledge of the position of their hind legs gripping the leaf edge and the position of their head to keep them cutting on the curve and ensure that they never cut fragments that exceed their exceptional strength.

CWAN: Self-supervised learning for deep grape disease image composition

Grape leaf diseases seriously affect grape yield and directly lead to the loss of the industrial economy. An accurate diagnosis is crucial for effective spraying and control. Presently, the combination of image blending and a deep recognition model is the most effective method for accurately identifying grape leaf diseases. Existing methods of image blending depend primarily on single-channel and multi-scale channel blending, computing and optimizing the Poisson equation, and the iterative optimization of learning-based methods for simple composite results. Although these methods have had some success, they are not able to simultaneously address lesion and leaf gap size, color bleeding, and edge smoothness. In this paper, we propose a novel image blending method named cascade wavelet attention network (CWAN). Specifically, CWAN consists of a cascade wavelet attention (CWA) and a blending autoencoder. First, we build a CWA to decompose the image into a multi-level and multi-scale frequency domain image. Then, the detailed features of the source and target domains are extracted, and the edges are smoothed. Following this, a shared decoder is designed to fuse these features in the corresponding frequency-domain layers, and the result serves as the attention feature. Finally, we design a blending autoencoder with a feature fusion mechanism to seamlessly blend lesions and leaves enhanced by CWA. We also construct a weighted blended loss function to avoid leaf color infiltration into the lesion in the blended image. Comprehensive experiments on two grape leaf disease datasets. Qualitative and quantitative results demonstrate the superiority and effectiveness of our model.

Fractal-Thermodynamic system analogy and complexity of plant leaves

More precise measurements of the complexity of leaf shapes can open new pathways to understanding plant adaptation and resilience in the face of global changes. We present a method to measure the complexity of plant leaf shapes by relating their fractal dimension to topological entropy. Our method relies on ‘segmental fractal complexity’ and stems from a fractal-thermodynamic system analogy. The complexity of plant leaf shapes is an algebraic combination of the fractal dimension of the components, leaf lamina, background, and leaf edge. We applied this method to leaf forms of 42 tropical plant species. Segmental fractal complexity is an improvement over the leaf dissection index because of its ability to capture the spatial positioning of a leaf’s lamina, edge, and background. It is also an advancement over conventional geometric and fractal dimension-based measures of leaf complexity because it does not entail information loss due to the pre-processing and is perceptibly simple.

Physiological and Nutritional Responses of Ungrafted Merlot and Cabernet Sauvignon Vines or Grafted to 101-14 Mgt and 1103P Rootstocks Exposed to an Excess of Boron

The aim of this study is to analyze the effect of excess boron (B) on the nutrient uptake, growth, and physiological performance of grapevines. Merlot and Cabernet Franc grapevines, either own-rooted or grafted onto 1103P and 101-14 Mgt rootstocks, were exposed in a hydroponic pot experiment to 0.5 mM boron for sixty days. Twenty-five days following the beginning of B treatment, the first symptoms of boron toxicity appeared, including leaf edge and margin yellowing, subsequent necrosis, and cupping of leaf blades. At harvest, sixty days after the start of the experiment, B concentration of the treated vines increased in all parts of the vine in the following order: Leaves > Roots > Trunks > Shoots. Leaf Boron concentration in treated vines ranged from 980.67 to 1064.37 mg kg−1 d.w. Boron excess significantly reduced the concentrations of all macro and micronutrients studied in this experiment. The total leaf chlorophyll (Chl) concentration decreased from 35.46 to 44.45%, thirty and sixty days, respectively, from the beginning of the boron treatments. In addition, an excess amount of boron resulted in a dramatic decrease in net CO2 assimilation rate, stem water potential, and PSII maximum quantum yield, irrespective of vine type (own-rooted or grafted). At the end of the experimental period, the total leaf phenolic content increased by 71.73% in Merlot and by 71.16% in Cabernet Franc due to Boron stress. The tressed vines grafted onto 1103P showed increased shoot and root dry weights, leaf chlorophyll content, CO2 assimilation rates, and Fv/Fm ratio compared to vines grafted onto 101-14 Mgt. It was found that rootstocks play an important role in B toxicity. The results showed that the leaf accumulation of boron was delayed to a greater extent by 1103P rootstock compared to 101-14 Mgt, resulting in the earlier appearance of leaf toxicity symptoms in vines grafted onto 101-14 Mgt rootstock compared to 1103P.

Pharmacobotanical study of Psychotria carthagenensis Jacq. (Rubiaceae), a species known as toxic and medicinal

Psychotria carthagenensis (Rubiaceae), popularly known as “erva-de-rato”, is known as poisonous, and its leaves are used as a constituent of “ayahuasca”. An anatomical study of its leaves was carried out to define parameters to support its taxonomy and quality control of ethnodrugs. Transverse and paradermic sections of petioles and leaf blades were made following the usual techniques of botanical anatomy. All semi-permanent laminas were then analyzed and photographed by light microscopy. Leaf blades were also studied with the support of the scanning electron microscope. Psychotria carthagenensis has hypostomatic epidermis, 1-2-stratified, in cross section, with three types of stomata (paracytic, anisocytic and anomocytic), and predominantly straight anticlinal cell walls, in frontal view, and glandular-peltate trichomes on both surfaces, the cuticle is smooth and thickened. The leaf edges are acute, mesophyll dorsiventral with the palisade parenchyma 1-seriate, and spongy parenchyma 4-seriate. The midrib is flat-convex with 4 bundles; petiole is semicircular with lateral projections with 9 vascular bundles. Midrib and petiole have collateral vascular system. Anisocytic and anomocytic stomata, glandular-peltate trichomes, petiole with the central bundle invaginate at the end, the syntopism of epicuticular waxes are distinctive parameters for P. carthagenensis, which support the standardization of its leaves used as medicines, in addition to contributing to the systematic of the Psychotria genus.

First Report of Colletotrichum fructicola Causing anthracnose on macadamia in China.

Macadamia (Macadamia ternifolia Maiden and Betche) is an important commercial crop in the world and has the reputation of being the king of nuts (Liu et al. 2019). In August 2020, symptoms of anthracnose appeared on leaves of macadamia in Chongzuo, Guangxi Province, China, with an incidence of 15-20%. The disease developed from the edge of leaf. Initially, the disease symptoms on leaves were faded green spots, light yellow. After expanding and linking together, the leaves appeared brown or black irregular spots, and the edges of diseased leaves dried up and formed large necrosis, eventually leading to defoliation. A large number of orange-yellow spots (acervuli) developed on the diseased parts. Under high humidity conditions, the diseased part was grayish-brown or black, and a large number of yellowish-brown conidia were produced on the leaf surface (Fig.1 A-E). Ten symptomatic leaves were collected and washed with distilled water. Twelve lesion marginal tissues were sterilized with 75% ethanol (V/V) for 30 s and 1% NaOCl for 1min and rinsed with sterile distilled water, plated on potato dextrose agar (PDA) and incubated at 28°C under light. After 3 days, the incubated samples all produced similar cultural morphology. One isolate named GXMC2 as a representative was selected for following study. The colony by single-spore purification on PDA were grayish green with a white outer ring and cottony on surface, pale blackish green in reverse side (Fig.1 F). Conidia with oil droplets were solitary, cylindrical, transparent and measuring 13.78 to 19.25 μm (average 16.90 μm) × 5.14 to 7.33 μm (average 6.23 μm) (n=100) (Fig.1 G). Appressoria were brown to dark brown, with different shapes such as ovoid, elliptical or irregular, some with lobes. The average size was 7.89 to 13.25 μm (average 10.64 μm) × 5.76 to 9.02 μm (average 7.86 μm) (n=100) (Fig.1 H). No setae were found. The isolate was identified as Colletotrichum fructicola on the basis of the morphology of the colonies, conidia and appressoria (Park et al. 2018). The six target gene sequences, including internal transcribed spacer (ITS), β-tubulin (TUB), actin (ACT), histone3 (HIS3), chitin synthase A (CHS), and glyceraldehydes-3-phosphate dehydrogenase (GAPHD) (Qiu et al. 2020), were selected for PCR amplification. The resulting sequences were deposited in GenBank under accession numbers MZ821661, MZ821660, MZ821662, MZ821663, MZ821664 and MZ821665 respectively. Phylogenetic analysis of the concatenated sequences were performed with MEGA 7.0 software. The isolate was grouped in the same clade as other C. fructicola (Fig.2). In May 2022, Inoculation was conducted in the field. Four-year-old macadamia leaves were disinfected with 75% alcohol. The conidial suspension was sprayed on 5 unwounded healthy leaves, and 5 leaves sprayed with sterile distilled water served as control. The experiment was replicated 3 times, with each replicate containing 5 leaves. The average daily temperature and average daily relative humidity in the field were 30°C and 62%, respectively. After 2 days, yellow-brown spots appeared on the inoculated leaves and expanded outward. After 4 days, the diseased areas were dark brown, and the controls remained asymptomatic. The same fungal pathogen was reisolated and purified from inoculated leaves and the identity was confirmed by morphological characterization and molecular analysis, confirming Koch's postulates (Fig.1 I-J). In China, C. fructicola has been reported on Passiflora edulis Sims, Brassica parachinensis, Illicium verum, Peucedanum praeruptorum, etc. (Li et al. 2021; Yu et al. 2022; Zhao et al. 2021; Ma et al. 2020). To our knowledge, this is the first report of anthracnose of macadamia caused by C. fructicola in China. This study provides the basis for further research on this disease.

Plant Species Classification Using Leaf Edge Feature Combination with Morphological Transformations and SIFT Key Point

This paper presents a new approach to plant classification by using leaf edge feature combination with Morphological Transformations and defining key points on leaf edge with SIFT. There are three steps in the process. Image preprocessing, feature extraction, and image classification. In the image preprocessing step, image noise is removed with Morphological Transformations and leaf edge detect with Canny Edge Detection. The leaf edge is identified with SIFT, and the plant leaf feature was extracted by CNN according to the proposed method. The plant leaves are then classified by random forest. Experiments were performed on the PlantVillage dataset of 10 classes, 5 classes of healthy leaves, and 5 classes of diseased leaves. The results showed that the proposed method was able to classify plant species more accurately than using features based on leaf shape and texture. The proposed method has an accuracy of 95.62%.

First report of Watermelon crinkle leaf-associated virus 2 infecting watermelon (Citrullus lanatus) in Oklahoma.

Watermelon (Citrullus lanatus) is one of the major cucurbit crops in Oklahoma, which is grown on >1,200 acres. It contributes $16 million to the state's economy (Shrefler et al., 2017; NASS, 2022). During the 2021 growing season, virus-like symptoms on watermelon plants were observed in a grower's field in Blaine County, Oklahoma. These symptoms included mottling, crinkled leaf edges, and a unique yellow mosaic pattern (Fig. 1). Leaf tissue samples were randomly collected from nine plants and total RNA was extracted using Spectrum Plant Total RNA Kit (Sigma-Aldrich). Total RNA from one sample (named BL13) was subjected to high-throughput sequencing (HTS) on the NextSeq 500/550 High-Output kit v2.5 (Illumina, USA) at the genomic facility of Oklahoma State University. A total of 21,52,786 trimmed pair-end reads were assembled using CLC Genomics Workbench (v12.0.3) (Qiagen, Inc.) and subjected to BLASTn analysis. Of these, three contigs of 6,626 bp, 1,383 bp and 1,233 bp (average coverage 20,658X) showed 99% nucleotide (nt) sequence identity with RNA1 of a watermelon crinkle leaf-associated virus (WCLaV-2) isolate from Brazil (LC636073). The HTS data for BL13 samples also revealed three contigs of 263 pb, 567 bp and 1,066 bp that matched with cucumis melo crytpic virus isolate CmCV-HLI but was not confirmed by RT-PCR. The presence of WCLaV-2 in the BL13 sample was confirmed by RT-PCR using primers (RNA1-F: 5'-CAAAACGCCCATAAG AATAG-3'and RNA1-R: 5'- CTCCATTAATGAGAACTAGGAG-3') which amplified a 1.2 kb segment of the RNA1. The PCR product was confirmed on 1% agarose gel, cloned and three independent recombinant clones Sanger sequenced (Eurofins Genomics LLC, Louisville, KY, USA). The resulting consensus sequence (1.2 Kb) (ON453838) was subjected to a BLASTn search against the Genbank databases, resulting in 99.76% nt identity with WCLaV-2 RNA1 (Accession no. LC636073). Screening of the remaining eight symptomatic samples by RT-PCR revealed another positive sample (named BL7) for WCLaV-2. Consensus nt sequence (1.2 Kb) analysis for the virus isolate from the BL7 sample (Accession no. ON453839) shared 99.84% nt identities with WCLaV-2 RNA1 (LC636073). Total RNA from BL13 and BL7 samples, as well as the remaining seven samples, were tested against three major potyviruses (PRSV-W, WMV, and ZYMV) by multiplex RT-PCR (Rajbanshi & Ali, 2019). Both BL13 and BL7 samples were negative to all three potyviruses but the other eight samples were positive to one or two of the potyviruses. WCLaV-2 is a negative-sense ssRNA virus (family Phenuiviridae) and has been recently reported from watermelon in China (Xin et al., 2017) and Brazil (Maeda et al. 2022). In the United States, it has been reported from Florida (Hendrick et al., 2021), Georgia (Adeleke et al., 2022), and Texas (Hernandez et al., 2021). The mode of transmission of WCLaV-2 and its direct effect on watermelon fruit is not known (Xin et al., 2017; Maeda et al., 2022). Our results report for the first time the occurrence of WCLaV-2 infecting watermelon naturally in Oklahoma and show a further potential threat to watermelon production in the State. Further studies are needed to determine the incidence of WCLaV-2 in other counties of Oklahoma.

Comparative transcriptome analysis reveals the regulatory mechanisms of two tropical water lilies in response to cold stress

BackgroundTropical water lily is an aquatic plant with high ornamental value, but it cannot overwinter naturally at high latitudes. The temperature drop has become a key factor restricting the development and promotion of the industry.ResultsThe responses of Nymphaea lotus and Nymphaea rubra to cold stress were analyzed from the perspective of physiology and transcriptomics. Under the cold stress, Nymphaea rubra had obvious leaf edge curling and chlorosis. The degree of peroxidation of its membrane was higher than that of Nymphaea lotus, and the content of photosynthetic pigments also decreased more than that of Nymphaea lotus. The soluble sugar content, SOD enzyme activity and CAT enzyme activity of Nymphaea lotus were higher than those of Nymphaea rubra. This indicated that there were significant differences in the cold sensitivity of the two varieties. GO enrichment and KEGG pathway analysis showed that many stress response genes and pathways were affected and enriched to varying degrees under the cold stress, especially plant hormone signal transduction, metabolic pathways and some transcription factor genes were from ZAT gene family or WKRY gene family. The key transcription factor ZAT12 protein in the cold stress response process has a C2H2 conserved domain, and the protein is localized in the nucleus. Under the cold stress, overexpression of the NlZAT12 gene in Arabidopsis thaliana increased the expression of some cold-responsive protein genes. The content of reactive oxygen species and MDA in transgenic Arabidopsis thaliana was lower, and the content of soluble sugar was higher, indicating that overexpression of NlZAT12 can improve the cold tolerance of Arabidopsis thaliana.ConclusionWe demonstrate that ethylene signalling and reactive oxygen species signalling play critical roles in the response of the two cultivars to cold stress. The key gene NlZAT12 for improving cold tolerance was identified. Our study provides a theoretical basis for revealing the molecular mechanism of tropical water lily in response to cold stress.

Keanekaragaman Morfologis Sukun [Artocarpus altilis (Park.) Fosberg. var. non-seminiferus] Di Daerah Banyumas

Breadfruit [Artocarpus altilis (Park.) Fosberg] is a plant that have different morphological variations in each region. The Banyumas area is an area that is very suitable for the growth of breadfruit. This study was aimed to determine the diversity of breadfruit plants based on their morphological characteristics. This research was conducted using a survey method, then the data were analyzed descriptively. The research variable was the morphological characteristics of the breadfruit plant, the parameters were the morphological of the canopy, buttress roots, stems, leaves, flowers, and fruits. The results showed that the morphological variations of breadfruit were found in the shape of the canopy varies, namely broad pyramid, pyramid, ovoid, round, and irregular, some have buttress roots and none, fruit shape varies, namely round and oval. Leaf blade length varies between 26-56 cm, leaf blade width varies between 20-45 cm, leaf stalk length varies between 3-6 cm, leaf shape is ovoid, upper leaf surface is smooth, lower leaf surface is rough, leaf edge incised, the tip of the leaf is tapered, the base of the leaf is wedged, the color of the leaf is dark green. Male flower length varies between 9-17 cm, male flower color varies, namely light green and brownish, male flower shape resembles a club, female flower diameter varies between 5-6 cm, female flower shape is round, female flower color is light green. Fruit weight varies between 450-1250 g, fruit diameter varies between 9-18 cm, fruit skin color is green, flesh color is white to yellowish white, flesh texture is smooth, fruit skin pattern is polygonal, and seeds are round, black.

Cotton leaf segmentation with composite backbone architecture combining convolution and attention.

Plant leaf segmentation, especially leaf edge accurate recognition, is the data support for automatically measuring plant phenotypic parameters. However, adjusting the backbone in the current cutting-edge segmentation model for cotton leaf segmentation applications requires various trial and error costs (e.g., expert experience and computing costs). Thus, a simple and effective semantic segmentation architecture (our model) based on the composite backbone was proposed, considering the computational requirements of the mainstream Transformer backbone integrating attention mechanism. The composite backbone was composed of CoAtNet and Xception. CoAtNet integrated the attention mechanism of the Transformers into the convolution operation. The experimental results showed that our model outperformed the benchmark segmentation models PSPNet, DANet, CPNet, and DeepLab v3+ on the cotton leaf dataset, especially on the leaf edge segmentation (MIoU: 0.940, BIoU: 0.608). The composite backbone of our model integrated the convolution of the convolutional neural networks and the attention of the Transformers, which alleviated the computing power requirements of the Transformers under excellent performance. Our model reduces the trial and error cost of adjusting the segmentation model architecture for specific agricultural applications and provides a potential scheme for high-throughput phenotypic feature detection of plants.

Effects of chlorine and peroxyacetic acid wash treatments on growth kinetics of Salmonella in fresh-cut lettuce

Fresh-cut produces are often consumed uncooked, thus proper sanitation is essential for preventing cross contamination. The reduction and subsequent growth of Salmonella enterica sv Thompson were studied in pre-cut iceberg lettuce washed with simulated wash water (SWW), sodium hypochlorite (SH, free chlorine 25 mg/L), and peroxyacetic acid (PAA, 80 mg/L) and stored for 9 days under modified atmosphere at 9, 13, and 18 °C. Differences in reduction between SH and PAA were non-existent. Overall, visual quality, dehydration, leaf edge and superficial browning and aroma during storage at 9 °C were similar among treatments, but negative effects increased with temperature. These results demonstrated that PAA can be used as an effective alternative to chlorine for the disinfection of Salmonella spp. in fresh-cut lettuce. The growth of Salmonella enterica sv Thompson was successfully described with the Baranyi and Roberts growth model in the studied storage temperature range, and after treatment with SWW, chlorine, and PAA. Subsequently, predictive secondary models were used to describe the relationship between growth rates and temperature based on the models’ family described by Bělehrádek. Interestingly, the exposure to disinfectants biased growth kinetics of Salmonella during storage. Below 12 °C, growth rates in lettuce treated with disinfectant (0.010–0.011 log CFU/h at 9 °C) were lower than those in lettuce washed with water (0.016 log CFU/h at 9 °C); whereas at higher temperatures, the effect was the opposite. Thus, in this case, the growth rate values registered at 18 °C for lettuce treated with disinfectant were 0.048–0.054 log CFU/h compared to a value of 0.038 log CFU/h for lettuce treated with only water. The data and models developed in this study will be crucial to describing the wash-related dynamics of Salmonella in a risk assessment framework applied to fresh-cut produce, providing more complete and accurate risk estimates.

Physiological and anatomical responses of Eugenia dysenterica to glyphosate

Abstract Brazil is among the countries that most use pesticides in the world. These chemicals cause undesirable changes in ecosystems, particularly the contamination of non-target native forest species through drift. The nuisances caused by pesticides go beyond environmental damage and include public health problems. The objective of this work was to evaluate the effects of glyphosate on leaf gas exchange, photosynthetic pigments and morphoanatomy of seedlings of Eugenia dysenterica. The visual toxicity, physiological and morphoanatomical characteristics of E. dysenterica, when exposed to concentrations of 0, 550, 1110 and 2220 g a.e. ha-1 of glyphosate, were analyzed. The results indicate that the herbicide caused toxicity in the leaves in all treatments. Reductions in photosynthesis (A), stomatal conductance (gs), and transpiration (E) at 47 DAA, were also identified. Glyphosate caused damage to the anatomical structures of E. dysenterica leaves. From the data analyzed it is possible to affirm that plants of E. dysenterica are sensitive to the action of glyphosate. Visible symptoms such as chlorosis and necrosis in the leaf edge are indicators that can be used by rural communities as a warning of the risk of contamination.

A Precise Image-Based Tomato Leaf Disease Detection Approach Using PLPNet.

Tomato leaf diseases have a significant impact on tomato cultivation modernization. Object detection is an important technique for disease prevention since it may collect reliable disease information. Tomato leaf diseases occur in a variety of environments, which can lead to intraclass variability and interclass similarity in the disease. Tomato plants are commonly planted in soil. When a disease occurs near the leaf's edge, the soil backdrop in the image tends to interfere with the infected region. These problems can make tomato detection challenging. In this paper, we propose a precise image-based tomato leaf disease detection approach using PLPNet. First, a perceptual adaptive convolution module is proposed. It can effectively extract the disease's defining characteristics. Second, a location reinforcement attention mechanism is proposed at the neck of the network. It suppresses the interference of the soil backdrop and prevents extraneous information from accessing the network's feature fusion phase. Then, a proximity feature aggregation network with switchable atrous convolution and deconvolution is proposed by combining the mechanisms of secondary observation and feature consistency. The network solves the problem of disease interclass similarities. Finally, the experimental results show that PLPNet achieved 94.5% mean average precision with 50% thresholds (mAP50), 54.4% average recall (AR), and 25.45 frames per second (FPS) on a self-built dataset. The model is more accurate and specific for the detection of tomato leaf diseases than other popular detectors. Our proposed method may effectively improve conventional tomato leaf disease detection and provide modern tomato cultivation management with reference experience.

First Report of Pratylenchoides leiocauda parasitic on Perilla frutescenes in the Republic of Korea.

Perilla (Perilla frutescens (L.) Britton var. japonica) is an annual herbaceous crop belonging to Lamiaceae. It is one of the most important crops in Korea. A survey of plant parasitic nematodes was carried out in 70 perilla fields in Geumsan and Miryang, Korea in 2020. Migratory endo-parasitic nematodes were extracted from the perilla roots using modified root incubation methods (Mountain and Patrick, 1959). False root-lesion nematodes (Pratylenchoides) were recovered from 41.4% of the fields. They were identified using morphological and molecular analyses. Among the Pratylenchoides species, Pratylenchoides leiocauda was described in France from soil around non-identified grass and weeds. P. leiocauda is reported to weaken the root systems of tomato, potato and strawberry (Sher, 1970; Li et al., 2020). The morphological characteristics of males and females from the 2020 survey were very similar to P. leiocauda. The lateral field contained six incisures and the pharyngeal glands overlapped the intestine dorsally for 1-2 times the body width. Additionally, they had a second nucleus near the pharyngeal intestine valve, female tails with incisures, and a smooth conical tail with 18-23 annules. Measurements and micrographs with the light-microscope (DM5000, Leica, Germany) and camera (DFC450, Leica, Germany) were taken from females (n=23) for mean, standard deviation and range of body length: 824.5 ± 71.0 (657.7-993.8) µm, maximum body width: 28.4 ± 2.7 (24.8-36.2) µm, stylet length: 22.8 ± 0.7 (21.4-24.0) µm and percent of distance from anterior end to vulva / body length: 57.7 ± 1.4 (54.0-60.3). Males (n=5) were characterized by a body length: 653.5 ± 64.3 (555.3-714.7) µm, a stylet length: 20.9 ± 1.0 (19.7-22.0) µm and a spicule length: 26.1 ± 2.5 (22.3-28.5) µm. Morphological measurements and characteristics (Fig. 1A-F) were compared to previous descriptions of P. leiocauda. As a result, the Korean population was larger than that of the originally described population from France, and was more similar to the Chinese population (Sher, 1970; Azizi et al., 2016; Li et al., 2020). In addition, PCR was performed for the COⅠ, LSU rRNA D2-D3 and ITS region using the primers (Mwesige et al., 2020). The sequenced COⅠ, LSU rRNA D2-D3 segments and ITS region are 447, 776 and 777 bp, respectively. The newly obtained sequences were submitted to GenBank database under accession numbers MZ418130, MZ414163 and MZ418133 of ITS region. A BLASTn search of the LSU rRNA D2-D3 sequence was most similar to P. leiocauda (MN539650), which is the species isolated from tomato in China (Li et al., 2020). The identities of these two sequences were 99.9% (775/776), with no insertions/deletions. The phylogenetic relationships strongly support P. leiocauda (Fig. 1G). Symptoms of perilla associated with P. leiocauda under field conditions included small and curled leaves, chlorosis of leaf edges, dark brown root epidermis and root necrosis (Fig. 2A, B). Koch's postulates were completed by inoculating 100 P. leiocauda into ten 45-cm-in-diameter pots filled with sterilized sandy loam soil and planted with perilla cultivar 'Ipdeulkkae 1-ho'. The potted plants were maintained for 50 days at 25℃ under greenhouse conditions. A P. leiocauda reproduction factor was 1.45 ± 0.20 was observed at the end of the trial, with 106 ± 21.6 recovered from soil and 39 ± 6.7 from root tissue. The root and shoot symptoms in the greenhouse trial were the same as those observed under field conditions (Fig. 2C, D). This, therefore, is the first record of P. leiocauda associated with perilla in Korea and management is warranted.