Leaf Scars Research Articles

The Carboniferous Gondwanan lycophyte Bumbudendron, revisited

The type material of Bumbudendron is reviewed in the light of current knowledge about fossil lycophytes. The bark is characterized having cushions with an infrafoliar bladder and a ligule. The variation in leaf bases and leaf scars and their presence may not only depend on the plant’s age or position on the stem, but also the plant’s preservation. The diagnosis of the genus is emended to include the presence of a ligule and a ligule pit in sterile and fertile leaves, the presence or absence of a preserved leaf scar, and variations in size and shape of the cushions resulting from preservation. Bumbudendron nitidum is here regarded as a synonym of B. millanii, the latter name having priority. In this concept, genus Bumbudendron comprises five species: B. paganzianum and B. millanii (Carboniferous of Argentina and Brazil), B. versiforme (Carboniferous and Lower Permian of Argentina and Uruguay), B. patagonicum (Permian of Argentina), and B. peruvianum (Lower Carboniferous of Peru). A review of the species of lycophytes from India, Niger, Ghana, and Egypt is suggested to determine whether they are assignable to Bumbudendron, and thus to define the geographic range of this genus.

Evaluation of Ten Alternative Treatments for the Management of Harlequin Bug (Murgantia histrionica) on Brassica Crops.

Harlequin bug (Murgantia histrionica) poses a significant threat to cruciferous vegetable crops, leading to economic losses and challenges in sustainable agriculture. This 2-year field study evaluated the efficacy of exclusion netting and selected biopesticides in controlling harlequin bug populations in a field-grown broccoli crop. Treatments included an untreated control, industry standards Azera and Entrust, and ProtekNet mesh netting. Additionally, three commercial essential oil treatments including Essentria IC-3, Nature-Cide, and Zero Tolerance were tested along with two bokashi fermented composting products BrewKashi and Oriental Herbal Nutrient (OHN). During both the first and second year of the study, none of the commercially produced essential oil products or bokashi products were effective in controlling harlequin bug or preventing leaf scars. Conversely, ProtekNet consistently provided the highest level of protection against harlequin bugs of all stages as well as leaf damage scars; it also provided the largest broccoli head width and highest yield. Entrust showed similar results compared to ProtekNet, both with the control of harlequin bug life stages and with leaf scars. These findings indicate that both ProtekNet and Entrust are effective organic alternatives for managing harlequin bug on broccoli, while the selected essential oil and bokashi products do not appear to be effective.

Determining the Main Infection Courts in Sweet Cherry Trees of the Canker Pathogens Calosphaeria pulchella, Cytospora sorbicola, and Eutypa lata.

The major fungal canker pathogens causing branch dieback of sweet cherry trees in California include Calosphaeria pulchella, Cytospora sorbicola, and Eutypa lata. These pathogens have long been known to infect cherry trees mainly through pruning wounds. However, recent field observations revealed numerous shoots and fruiting spurs exhibiting dieback symptoms with no apparent pruning wounds or mechanical injuries. Accordingly, this study was conducted to assess the incidence of the three pathogens in symptomatic terminal shoots and dying fruiting spurs, in addition to the wood below pruning wounds in branches. Surveys were conducted in five sweet cherry orchards across three counties in California. We also investigated the possibility that leaf scars, bud scars, and wounds resulting from fruit picking could serve as infection courts for Cal. pulchella, Cyt. sorbicola, and E. lata by means of artificial inoculations in the field. Orchard surveys revealed that Cal. pulchella had the highest pathogen incidence below pruning wounds in branch samples, followed by Cyt. sorbicola and E. lata. Among terminal shoots with dieback symptoms and dying fruiting spurs, Cyt. sorbicola was the most prevalent, followed by Cal. pulchella. Results from field inoculations indicated that fruit-picking wounds could serve as important infection courts for Cal. pulchella, Cyt. sorbicola, and E. lata, with average pathogen recovery of 41.5, 63, and 36.2%, respectively. Results also indicated that leaf and bud scars could serve as an entry site for Cyt. sorbicola, although recovery was relatively low. The present study is the first to identify harvest-induced wounds on fruiting spurs of sweet cherry as an important infection court of Cal. pulchella, Cyt. sorbicola, and E. lata.

Comparative Analysis of Dry Market Sample of Acorus calamus Linn. Sample with Pharmacopoeial Standards

A comparative analysis of market-available dry Acorus calamus Rhizome samples with pharmacopoeial standards provides valuable insights into the quality and authenticity of these products. The study revealed significant variations in morphological features among the market samples, highlighting the need for stringent quality control measures. The sample was identified as Acorus calamus Linn. While the drug meets API standards, it lacks a few features. Most of the samples are of irregular shape rather than cylindrical, and triangular, transverse leaf scars were absent. These observations suggest potential variations or discrepancies in the market-available samples compared to pharmacopoeial standards. Further investigations and quality control measures are essential to ensure the consistency and efficacy of Acorus calamus products in traditional and modern medicinal practices.

Deep Learning Approaches for Sunflower Disease Classification: A Study of Convolutional Neural Networks with Squeeze and Excitation Attention Blocks

Diseases in agricultural plants are one of the most important problems of agricultural production. These diseases cause decreases in production and this poses a serious problem for food safety. One of the agricultural products is sunflower. Helianthus annuus, generally known as sunflower, is an agricultural plant with high economic value grown due to its drought-resistant and oil seeds. In this study, it is aimed to classify the diseases seen in sunflower leaves and flowers by applying deep learning models. First of all, it was classified with ResNet101 and ResNext101, which are pre-trained CNN models, and then it was classified by adding squeeze and excitation blocks to these networks and the results were compared. In the study, a data set containing gray mold, downy mildew, and leaf scars diseases affecting the sunflower crop was used. In our study, original Resnet101, SE-Resnet101, ResNext101, and SE-ResNext101 deep-learning models were used to classify sunflower diseases. For the original images, the classification accuracy of 91.48% with Resnet101, 92.55% with SE-Resnet101, 92.55% with ResNext101, and 94.68% with SE-ResNext101 was achieved. The same models were also suitable for augmented images and classification accuracies of Resnet101 99.20%, SE-Resnet101 99.47%, ResNext101 98.94%, and SE-ResNext101 99.84% were achieved. The study revealed a comparative analysis of deep learning models for the classification of some diseases in the Sunflower plant. In the analysis, it was seen that SE blocks increased the classification performance for this dataset. Application of these models to real-world agricultural scenarios holds promise for early disease detection and response and may help reduce potential crop losses.

Plant morpho evo-devo.

Evo-devo is often thought of as being the study of which genes underlie which phenotypes. However, evo-devo is much more than this, especially in plant science. In leaf scars along stems, cell changes across wood growth rings, or flowers along inflorescences, plants trace a record of their own development. Plant morpho evo-devo provides data that genes could never furnish on themes such as heterochrony, the evolution of temporal phenotypes, modularity, and phenotype-first evolution. As plant science surges into increasingly -omic realms, it is essential to keep plant morpho evo-devo in full view as an honored member of the evo-devo canon, ensuring that plant scientists can, wherever they are, generate fundamental insights at the appropriate level of biological organization.

Relative contribution of season, site, scion and rootstock genotype, and susceptibility to European canker to the variability in bacterial and fungal communities in apple leaf scar tissues

AbstractNeonectria ditissima infects apple trees through wounds, causing European canker. In the UK, the most important entry site for N. ditissima is leaf scar. Specific apple endophytes may contribute to cultivar resistance/tolerance to the pathogen. We assessed the relative effect of location, sampling time (season), and rootstock/scion genotype on bacterial and fungal endophyte communities in the apple leaf scar tissues of current‐season extension shoots and identified Operational Taxonomic Units (OTUs) with differential abundance between canker resistant and susceptible scions, and between rootstocks. Leaf scar tissues were sampled from two orchards at three times (10/2018, 06/2019 and 10/2019) for eight scion cultivars, each grafted onto two rootstocks, for profiling 16S and ITS rRNA regions. Endophyte composition was primarily affected by season (autumn vs. spring) and location (sites and blocks within site). There was a significant reduction in the community size in the spring, particularly for fungi, and species turnover between autumn and spring. This seasonal dynamics suggest that to protect leaf scars from N. ditissima infection in the autumn specific endophytes suppressing canker may have to be augmented annually around the leaf‐fall time. Scion and rootstock genotypes had limited effects on the endophyte community. A group of resistant cultivars differed from a group of susceptible ones in the relative abundance of many bacterial and fungal OTUs, most of which had low reads numbers. Nevertheless, several OTUs with high reads numbers differed in their relative abundance between resistant and susceptible scions, including OTUs from Sphingomonas, Methylobacterium, Vishniacozyma and Rhodotorula babjevae, and warrant further investigation for their potential role in host resistance/tolerance against N. ditissima.

Age Determination and Growth Characteristics of the Potentilla griffithii: A Comparison of Two Different Habitats in Western Sichuan Plateau, China.

This study proposes a rapid and non-destructive technique for determining the age of Potentilla griffithii individuals in the field by observing the sequence of leaf scars. Based on two- to three-year-old P. griffithii seedlings, planted in a common garden in the western Sichuan Plateau, China, the study found that the rates of basal leaf production were consistent, with leaves growing from March to April and falling off from October to December, leaving behind basal leaf scars. Thus, the age of individuals in situ could be determined by counting the leaf scars. Through this method, we determined the age structure and growth strategy of P. griffithii populations in two typical habitats in the western Sichuan Plateau. In open land habitats, the age structure of P. griffithii populations was relatively younger compared to understory habitats. In open land, P. griffithii tends to allocate more photosynthate terminal organs (leaves and fine roots) to absorbing more resources, as well as to its reproductive organs (flower stems and aggregate fruits), to expand the population. The P. griffithii population in the understory habitat is in its middle-age stage and concentrates more photosynthate in the coarse root part (e.g., the high coarse root mass fraction (FRMF)) to support the plant. Additionally, we found a significant correlation between P. griffithii plant age and various traits in open land habitats. Therefore, we conclude that plant age can be used as a good predictor of plant growth condition in open land. These results allow for predicting ecological processes, based on the ages and traits of P. griffithii plants, providing a theoretical basis to support the large-scale breeding of P. griffithii.

Validated SNAP markers based on the CYP P450 87 A3 gene in coconut (Cocos nucifera) are associated with yearly stem height increase

Abstract. Hatta ANNL, Sukma D, Maskromo I, Sudarsono S. 2023. Validated SNAP markers based on the CYP P450 87 A3 gene in coconut (Cocos nucifera) are associated with yearly stem height increase. Biodiversitas 24: 2503-2512. Tall and dwarf coconuts are coconut types used worldwide as the parents in hybrid coconut production, and they differ in their yearly stem height. The yearly stem height of coconuts is estimated as 11 leaf scars length. The CYP P450 87 A3 gene is essential in the yearly stem-height increase (YSI) character. This study aims to validate single nucleotide-amplified polymorphism (SNAP) markers based on sequence variabilities of the coconut CYP P450 87 A3 gene and analyze their association with the coconut YSI character. The CYP P450 87 A3 partial genomic fragments were PCR amplified, sequenced, and used to develop SNAP markers. The markers were subsequently validated using 155 samples of 31 coconut varieties. The analysis showed that at least 17 single nucleotide polymorphisms (SNPs) exist in the exon-1 and 2 of the coconut CYP P450 87 A3 gene, and SNAP markers were successfully developed. Single-locus analysis showed that the validated CYP2_SNP1 SNAP marker locus was associated with coconut YSI characters. The developed SNAP marker based on the partial CYP P450 87 A3 gene can potentially support future marker-assisted selection (MAS) in coconut breeding, especially for developing coconut with low YSI character.

From Endophyte Community Analysis to Field Application: Control of Apple Canker (Neonectria ditissima) with Epicoccum nigrum B14-1

Apple canker, caused by Neonectria ditissima (Tul. and C. Tul.) Samuels and Rossman, is a major disease of apples (Malus domestica) worldwide. N. ditissima infects through natural and artificial wounds. Infected wood develops canker lesions which girdle branches and main stems causing reduced yield and tree death. N. ditissima is difficult to control; removal of inoculum (cankers) is expensive and therefore seldom practiced, whilst effective chemical products are being banned and no biocontrol products have been found to be effective against N. ditissima. This study used cues from a previous apple endophyte community analysis to isolate and test fungal endophytes belonging to the genus Epicoccum as potential endophytic biocontrol agents. Epicoccum nigrum B14-1, isolated from healthy apple trees, antagonised N. ditissima in vitro and reduced the incidence of N. ditissima infections of leaf scars by 46.6% and pruning wounds by 5.3% in field conditions at leaf fall. Autumn application of B14-1 conidia increased E. nigrum abundance in apple tissues at 10–20 days post-inoculation by ca. 1.5×, but this returned to control levels after one year. E. nigrum B14-1 did not cause detrimental effects on apple foliage, buds, fruit, or growth and could therefore present a new biocontrol agent to manage N. ditissima in commercial apple production.

Morphology of wintering shoots of a rare species Exochorda serratifolia S. Moore in Primorsky Krai

The paper studies the morphology of winter shoots of the rare species Exochorda serratifolia S. Moore (Rosaceae Juss.) included in the Red Book of Primorsky Krai (Russian Federation) in the natural population (Khankaisky district of Primorsky Krai) and in culture (the arboretum of the Mountain Taiga Station of the Far Eastern Branch of the Russian Academy of Sciences) during 2020-2021. The studied morphological features (linear dimensions of the stem, buds and leaf scars, the number of metamers, bud scales, etc.) vary slightly. A number of morphological characteristics of the buds of Exochorda serratifolia – polyscaly, type of budding, the presence of a waxy coating are adaptive features to temperate continental climatic conditions. The obtained data on the morphology of overwintering shoots of Exochorda serratifolia can be used as additional diagnostic features for identification of the plant in a leafless state.

Re-study of Guangdedendron micrum from the Late Devonian Xinhang forest

BackgroundGuangdedendron micrum is the Late Devonian tree lycopsid that made up Xinhang fossil forest in Anhui, China, showing the earliest stigmarian rooting system. Based on new specimens of this lycopsid, the roots bearing rootlets, terminal parts of stems, vegetative leaves and monosporangiate strobili containing megaspores are researched in detail.ResultsThe roots with four robust rhizomorphs are largely expanded and approach the size of those of the Late Carboniferous giant tree lycopsids in swampy forests. The rootlets along rhizomorphic axis leave oval to circular scars after abscission. Narrow-fusiform leaf cushions display a leaf scar, vascular bundle and ligule pit. Cylindrical megasporangiate strobili are borne singly, in pairs, or occasionally once-dichotomized. Of each megasporophyll, the pedicel consists of a keel and possibly undeveloped alations, and the long-triangular lamina presents a heel. Megasporangium is sessile and contains multiple Lagenicula megaspores with distinct spines and a large gula.ConclusionsG. micrum displays large terminal monosporangiate strobili probably adapted to turbulent condition, and its megasporophylls together with multiple Lagenicula-type megaspores hint a possible primitive evolutionary status. These characteristics provide new insights into the evolution of fertile traits of early lycopsids.

Phenotypic traits of three local cassava (Manihot esculenta Crantz) genotypes cultivated by farmers in Rivers State, Nigeria

The study aimed to elucidate the morphological and anatomical traits for varietal delimitation and identification of three local cassava (Manihot esculenta var. aguregbu, var. cagbo and var. ekagon) varieties cultivated by farmers in Obio Akpor local government area of Rivers state. Twenty (20) qualitative and six (6) quantitative traits from the descriptors for cassava germplasm was used for morpho-characterization. The results obtained revealed phenotypic similarity for 15 qualitative traits among the three varieties. Trait differences was observed in the petiole color (red and green), prominence of foliar scars, and shape of stem, level of branching, root shape and constrictions. The distance between leaf scars was classed as short for all varieties but the metric value ranged from 1.6 cm for ekagon to 4.0 cm for aguregbu and cagbo. Other quantitative variation observed include petiole length (11.1 to 15.0 cm) and storage root length which was classified as medium (≤30 cm) and long (>30 cm). The number of leaf lobes was seven for all varieties. The epidermal traits showed a uniseriate epidermis with hypostomatic distribution. The stem, petiole, and midrib anatomy was similar in terms of tissue type and arrangement. However, the number of vascular bundles in the petiole was more in aguregbu (10) than in cagbo (8) and ekagon (8). The variable traits identified in this study provide diagnostic features that could aid in the identification of the three cassava genotypes.

The Influence of Host Genotypes on the Endophytes in the Leaf Scar Tissues of Apple Trees and Correlation of the Endophytes with Apple Canker (Neonectria ditissima) Development

Bacterial and fungal endophytes may help their host in terms of improved tolerance to abiotic and biotic stresses and enhanced growth. European apple canker, caused by Neonectria ditissima, is widespread in apple-growing regions. Infection by N. ditissima occurs through artificial or natural wounds, including leaf scars, picking wounds, and pruning cuts. Using F1 progeny trees in an experimental orchard derived from a cross between a canker-susceptible genotype and a canker-tolerant or -resistant genotype, we assessed both bacterial and fungal endophyte communities in apple leaf scars, and determined correlations of endophytes with canker development. All trees were artificially inoculated with an N. ditissima isolate postplanting. Specific components of apple endophytes as well as a number of individual fungal or bacterial groups in leaf scars were partially genetically controlled by host genotypes. Several bacterial groups were significantly correlated with canker-related traits, mostly positively associated with canker tolerance. A few fungal groups may facilitate canker development whereas others may compete with canker. However, most of these microbial groups could not be identified to the species level with confidence; even for those groups which could be assigned to the species level, there is insufficient knowledge about their ecological characteristics in relation to plants. The present results may be used to inform further research using biocontrol to manage N. ditissima and breeding for resistance.

Specific alleles as individual molecular markers and its association for sustainable breeding program in coconut palm

Molecular markers through individual identification have been used to protect plant varieties, identify varieties, purity test of seeds, and parented analysis in palm oil breeding programs. However, such identification has not been intensively developed on coconut palm. Therefore, this study aimed to obtain individual-specific markers of Indonesian coconut palms and their association. Coconut palms were selected randomly from 7accessions (74 palms) and then evaluated based on 10 SSR primers and main agro morphological characters. This research was carried out during 2017 and 2018 at Plant Breeding Laboratory, UGM, Yogyakarta and Mapanget Experimental Garden, IPCRI, North Sulawesi. CnCir 123-300, CnCir 87-120, CnCir J2-205 were unique alleles that resulted in this study. Five of eleven specific alleles were associated with essential traits of dwarf coconut. CnCir123-250 and CnCir123-300 were specific alleles associated with almost all characters observed in this study. CnCirA9-100 is the only allele that is negatively associated with the height of 11 leaf scars and positively associated with the main characters. Therefore, it is advantageous as a marker-assisted selection of the current coconut plant breeding program. Applications of specific molecular markers associated with essential characters are expected to improve the sustainability of coconut breeding programs.

Does apple canker develop independently on leaf scars of a single apple shoot?

European apple canker, caused by Neonectria ditissima, causes serious damage to apple trees, particularly young trees. Canker management is difficult because of the limited availability of effective fungicides, the long latency period, inoculum abundance and host resistance in commercial cultivars as well as the need for costly manual pruning interventions. To understand disease aggregation for more effective pruning management, we assessed whether canker infection and subsequent lesion development on leaf scars are independent from each other on the same shoot. Four inoculation experiments were conducted: one in glasshouse, and three in orchards. On each shoot, 10 consecutive leaf scars were inoculated and assessed for visible cankers over time in situ. Number of cankers developed per shoot as well as spatial distribution of these cankers within a shoot was statistically analysed. Most data of the number of visible canker lesions on a single shoot failed to fit binomial distributions (indicator for independence) and were fitted much better by beta binomial distributions. In a number of cases (4–20%), there appeared to be positive association between lesion development on neighbouring leaf scars. However, in one experiment where laboratory incubation and isolation of N. ditissima from inoculated but asymptomatic leaf scars (after eight months’ field incubation) were used the results suggested independence of canker development on a single shoot. We conclude that apparent aggregation of canker lesions on individual shoots is likely to originate from host responses. Such aggregation of canker lesions on individual shoots should be taken into consideration for field disease assessment and management.

Limited asymptomatic colonization of apple tree shoots by Neonectria ditissima following infection of leaf scars and pruning wounds

AbstractEuropean apple canker, caused by Neonectria ditissima, is an important disease of apple (Malus domestica). The fungus may reside in the tree without causing symptoms for up to a few years, thus making canker control difficult. Asymptomatic infections established in the nursery can result in severe canker outbreaks in newly established apple orchards. It has been suggested that N. ditissima might colonize the tree beyond the infection point during the asymptomatic stage. We investigated whether N. ditissima can colonize the internal tissues of apple shoots, both prior to and after visual symptoms. Apple trees were artificially inoculated via pruning wounds and leaf scars; then the pathogen was tracked at the inoculation point and beyond with isolation or real‐time quantitative PCR (qPCR). Before visual symptoms, N. ditissima could be detected in the infected pruning cut or leaf scar, but not at a distance of 10–15 mm from the entry point, or greater. Conversely, after symptom expression, the pathogen could be detected in the symptomless tissue at 10–15 mm from a canker lesion. This study demonstrated that the asymptomatic infection by N. ditissima can be detected using qPCR and that the pathogen does not grow systemically much beyond the initial entry point inside the plant before visual canker symptoms appear.

Euphorbia lakshminarasimhanii: a new pygmy succulent species from Konkan region of Maharashtra, India

Euphorbia lakshminarasimhanii (Euphorbiaceae), a new pygmy species belonging to the genus Euphorbia subg. Euphorbia sect. Euphorbia is described and illustrated from the Konkan region of Maharashtra, India. It is easily distinguished from all known Indian species by its unique sparsely‐branched pygmy habit, closely spaced and horizontally flattened tubercles, trapezoidal spine shields which are very close and overlapping at the apical region, giving a pouch like appearance, bifurcated spines completely separated by the leaf scar, leaves forming a crown, long bracts extending past the gland edge, coral red colored glands with indented margins, male florets 10 per fascicle, and capsule having globose cocci with thin keels.

Transposon Mutagenesis of Pseudomonas syringae Pathovars syringae and morsprunorum to Identify Genes Involved in Bacterial Canker Disease of Cherry.

Bacterial canker of Prunus, affecting economically important stone fruit crops including cherry, peach, apricot and plum, is caused by the plant pathogen Pseudomonas syringae (P.s.). Strains from two pathovars—P.s. pv. syringae (Pss) and P.s. pv. morsprunorum race 1 (PsmR1) and 2 (PsmR2)—in three phylogenetically distant clades have convergently evolved to infect Prunus. The bacteria enter woody tissues through wounds and leaf scars, causing black necrotic cankers. Symptoms are also produced on blossom, fruit and leaves. Little is known about the mechanisms P.s. uses to colonise tree hosts such as Prunus. Here, we created transposon (Tn) mutant libraries in one strain of P.s. from each of the three clades and screened the mutants on immature cherry fruit to look for changes in virulence. Mutants (242) with either reduced or enhanced virulence were detected and further characterised by in vitro screens for biofilm formation, swarming ability, and pathogenicity on leaves and cut shoots. In total, 18 genes affecting virulence were selected, and these were involved in diverse functions including motility, type III secretion, membrane transport, amino acid synthesis, DNA repair and primary metabolism. Interestingly, mutation of the effector gene, hopAU1, led to an increase in virulence of Psm R2.

Rehamnia (Lycopodiophyta), a new enigmatic Late Devonian plant from Morocco

Rehamnia michardis Oukassou and Naugolnykh, gen. et sp. nov. is described from the Late Famennian of the Foum El Mejez area (Northern Rehamna, Moroccan Meseta). This is the first record of Late Devonian plant from the Rehamna Hercynian massif. The new enigmatic plant remains are preserved as compression and impression in quartzitic sandstone of the top of Dalaa Formation. The material is represented by six practically complete specimens including holotype. General morphology of the stems, leaf scars and phylloids are similar to the same organographic structures of some representatives of lycopodiopsids s.l. (division Lycopodiophyta). The study opens many new gateways for deeper understanding of the diversity of Devonian land plants, with some respect to Gondwana paleofloristic realm.