Adaxial Side Research Articles

Classifying adaxial and abaxial sides of diseased citrus leaves with selected hyperspectral bands and YOLOv8

Huanglongbing (HLB; citrus greening) and citrus canker are invasive diseases afflicting Florida citrus groves, causing financial losses through yield loss, smaller fruit, blemishes, premature fruit drop and/or eventual tree death. Often, symptoms of these diseases resemble those of other disease or disorders. Early detection of HLB and canker via in-grove leaf inspection can permit more effective mitigation tactics and management of groves. Autonomous, vision-based disease scouting in a grove offers a financial benefit to the Florida citrus industry. This study investigates the potential of hyperspectral reflectance imagery (HSI) for detecting and classifying these conditions in the presence of other, less consequential leaf defects. Leaves with visible symptoms of HLB, canker, zinc deficiency, scab, melanose, greasy spot, and a control set were collected and both sides were imaged with a line-scan hyperspectral camera. Spectral bands from this imagery were selected using two methods: an unsupervised method based on principal component analysis (PCA), a supervised method based on linear discriminant analysis (LDA), which were compared with randomly selected bands as a control. The YOLOv8 network architecture was trained to classify each side of these leaves with each band combination. LDA-selected bands from the front of the leaves yielded an overall classification accuracy of 87.09 %, with higher recall of melanose and precision of control than any other model tested. Leaves with HLB and zinc deficiency were classified most accurately, with both band selection methods yielding F1 scores of at least 0.955 and 0.934, respectively. These findings favor the use of supervised band selection for HSI-based in-grove disease detection.

Mentha choujunensis, a new species from Indian Trans-Himalayan region of Ladakh

Mentha choujunensis (Lamiaceae), a new species from Suru valley of district Kargil in Ladakh, Trans-Himalaya, India is described here. The new species can be distinguished from its closest congeneric M. longifolia in possessing prostate stem, leaves petiolate and ovate to ovate-lanceolate, sparsely pubescent, trichomes 1-celled on adaxial side and 2-celled on abaxial side, base oblique, margin serrate, calyx less than half the length of corolla tube, 8–10 veined, calyx teeth reddish brown with distal trichomes 3–4 celled long and corolla white. Photo-illustrations, comparison of diagnostic characters of the new species with M. longifolia and taxonomic key for the Indian species under section Mentha are provided to facilitate field identification.

Investigation of the effect of forced precipitation of working fluid on a vineyard sprayer for weed control

BACKGROUND: A distinctive feature of the sprayer presented is the possibility of more effective penetration of the working solution into the middle and lower tiers of weeds, as well as on the lower (abaxial) side of the leaf. This is ensured by the use of an air-liquid jet, which significantly increases the effectiveness of the applied chemical method of weed control. AIMS: Analysis of the effect of air jets on the deposition of chemicals on the surface of leaves of weeds. The penetration of the drug into the middle and lower tiers of plants, as well as deposition on the adaxial and abaxial sides of the leaves, is taken into account. METHODS: To combat unwanted vegetation, a special device was used, which was used in field research without air support, and with its use. With the help of the developed technique, spraying was carried out on indicator cards fixed on the upper, middle and lower tiers of the plant RESULTS: For the first time, an innovative technology based on the use of a flexible air distribution sleeve as part of a herbicide sprayer was proposed to combat weeds in vineyards. This sleeve ensures the precise supply of air flow from the fan to the spraying area of the working fluid. The result of such an air-liquid flow is improved efficiency and monodispersity of herbicide droplets, which, in turn, ensures uniform coverage of the lower tiers and the abaxial surface of the leaves of weeds. This innovative solution opens up new prospects in the fight against unwanted vegetation in the vineyards. CONCLUSIONS: The practical value of the proposed weed control technology is to increase the quality of the technological operation due to the forced precipitation of the working solution.

Acaricidal Efficacy of Abamectin against Tetranychus urticae Populations When Combined with Entomopathogenic Fungi

Tetranychus urticae (Acari: Tetranychidae) is a widespread and serious mite pest that infests tomato plants and causes economic losses worldwide. We investigated the acaricidal efficacy of two isolates of entomopathogenic fungi (EPF) Metarhizium robertsii (WG-7) and Beauveria bassiana (WG-12) alone and in combination with abamectin when applied topically to tomato leaf discs in the laboratory against T. urticae. We also evaluated the establishment and proliferation of T. urticae mite life stages on tomato plants in the greenhouse after application of each of the above treatments. The combination of abamectin with each EPF caused 100% mortality in T. urticae immatures after 2 days while each EPF or abamectin alone caused moderate mortality, not exceeding 74.2% 3 days post-exposure. Complete (100%) mortality of adults was observed after 5 days in leaf discs treated with M. robertsii plus abamectin whereas B. bassiana plus abamectin caused 100% mortality after 7 days. The mean number of eggs, emerged immatures, and adults were significantly reduced on both sides of the leaves (i.e., abaxial and adaxial sides) after using the combined application of M. robertsii or B. bassiana plus abamectin, compared to abamectin alone and controls. Our results reveal that the acaricidal efficacy of abamectin combined with either EPF was significantly better in managing the T. urticae life stages than either treatment alone under greenhouse conditions.

First Report of Powdery mildew Caused by Golovinomyces ambrosiae on Verbena × hybrida in the U.S.

Verbena × hybrida, also known as common garden verbena, has an important ornamental value for their wide range of flower colors and for attracting hummingbirds and butterflies. During the winter of 2021-2022 (December through February), more than 50% pot-grown verbena plants showed symptoms of powdery mildew in a field trial at a Syngenta Crop Protection research facility in Vero Beach, FL. Symptoms were characterized by the development of white, superficial mycelium on the adaxial side of leaves which, eventually, progressed to covering the whole surface of leaves, causing leaf discoloration, shoot distortion, and eventual plant death. Morphological characterization was carried out by observing powdery mildew colonies under the microscope. This powdery mildew forms dense patches of white mycelia, mainly on the adaxial leaf surfaces. The mycelium was a mat of hyphae with septa. Conidiophores were erect. The foot cells were straight, followed by one to three short cells bearing short chains of up to four conidia. The conidia were hyaline and ellipsoidal to doliiform in shape. Conidial germination is of the Eudoidium type. The conidia ranged from 25 to 32 μm long by 12 to 16 μm wide. The length to width ratio ranged between 1.6 and 2.3, but most were between 2.0 and 2.2. This is further verification of its identity as Golovinomyces ambrosiae and not Golovinomyces latisporus, because the length to width ratio of the latter species is consistently less than 2.0 (Qiu et al. 2020). Chasmothecia were not observed. Additionally, the ITS, GAPDH, and IGS regions were sequenced using the primer pairs ITS4/ITS5 (White et al. 1990), PMGAPDH1/PMGAPDH3R (Bradshaw et al. 2022a), and IGS-12a/NS1R (Carbone and Kohn 1999), respectively. The ITS region (GenBank number=PP924119) cannot distinguish between G. latisporus and G. ambrosiae and as such aligned 100% with both species on GenBank. However, the GAPDH and IGS regions can be used to distinguish G. ambrosiae from G. latisporus (Bradshaw et al. 2022b). The GAPDH (GenBank number=PP931995) and IGS (GenBank number=PP931996) regions aligned 100% with multiple G. ambrosiae sequences from GenBank including ON360708 and MK452567, respectively. The specimen was deposited in the Larry F. Grand Mycological Herbarium (NCSLG 24479). To confirm pathogenicity, 'Tuscany® Pink Picotee' and 'Quartz XP Violet with Eye' plugs were transplanted to 10-cm diameter pots containing ProMix potting mix and maintained in a greenhouse (± 26 °C). Inoculation was carried out 21 days after transplanting by touching infected leaves onto healthy leaves of 15 disease-free plants of each variety. Fifteen non-inoculated plants of each variety were used as controls. Typical powdery mildew symptoms and signs were first observed ten days after inoculation and the pathogen was more aggressive on 'Tuscany® Pink Picotee'. Symptoms were not observed on non-inoculated plants. The fungus was morphologically identical to the one originally recovered from infected plants in the field. There have been many reports of Golovinomyces spp. affecting Verbena spp. worldwide; however, this is the first report of G. ambrosiae causing powdery mildew on Verbena × hybrida in the U.S. (Braun and Cook, 2012, Choi et al., 2021; Bradshaw et al. 2024). Powdery mildews reduce plant quality and decreases the aesthetics value of infected plants, causing great losses to the ornamental industry. Correct identification of the causal agent is crucial to recommend appropriate control methods, as they may differ according to the pathogen species.

Sly-miR398b Mediates Mature Leaf Flattening by Orchestrating Auxin and H2O2 Signalling in Tomato.

Leaf flattening plays a pivotal role in optimizing light capture and enhancing photosynthesis efficiency. While extensive research has clarified the molecular mechanisms governing the initial stages of leaf flattening, understanding the maintenance of this process in mature leaves remains limited. Our investigation focused on sly-miR398b in tomatoes and revealed its crucial role in maintaining leaf flattening. In situ hybridization experiments indicated predominant expression of sly-miR398b in the abaxial side. Disrupting sly-miR398b using CRISPR/Cas9 relieved its suppression on target gene (Cu/Zn-SOD, SlCSD1), elevating SlCSD1 levels specifically on the abaxial side. Consequently, this asymmetrical expression of SlCSD1 increased hydrogen peroxide (H2O2) levels in the abaxial side, hindering auxin influx genes while promoting auxin efflux gene expression. This shift reduced auxin response gene expression in the abaxial side of mature leaves compared to the adaxial side, leading to leaf epinasty in sly-miR398b mutants. Exogenous H2O2 spraying induced leaf epinasty, downregulating SlGH3.5 and upregulating SlPIN3 and SlPIN4. Remarkably, spraying with 1-naphthalacetic acid (NAA) restored leaf flattening in sly-miR398b mutants. Our findings offer novel insights into mature leaf flattening maintenance via sly-miR398b's regulation of auxin and H2O2 signalling pathways.

Mechanical forces exerted on floral primordia with a novel experimental system modify floral development in Arabidopsis thaliana.

Mechanical forces play a crucial role in plant development, including floral development. We previously reported that the phyllotactic variation in the staminate flowers of Ceratophyllum demersum may be caused by mechanical forces on the adaxial side of floral primordia, which may be a common mechanism in angiosperms. On the basis of this result, we developed a novel experimental system for analysis of the effects of mechanical forces on the floral meristem of Arabidopsis thaliana, aiming to induce morphological changes in flowers. In this experimental system, a micromanipulator equipped with a micro device, which is shaped to conform with the contour of the abaxial side of the young floral primordium, is used to exert contact pressure on a floral primordium. In the present study, we conducted contact experiments using this system and successfully induced diverse morphological changes during floral primordial development. In several primordia, the tip of the abaxial sepal primordium was incised with two or three lobes. A different floral primordium developed an additional sepal on the abaxial side (i.e., two abaxial sepals). Additionally, we observed the fusion of sepals in some floral primordia. These results suggest that mechanical forces have multiple effects on floral development, and changes in the tensile stress pattern in the cells of floral primordia are induced by the mechanical forces exerted with the micro device. These effects, in turn, lead to morphological changes in the floral primordia.

Regulation mechanism of droplets wetting on banana leaf surface and its dynamic contact angle wetting model

The effective wetting and deposition of pesticide droplets on the leaf surface significantly affect the control of pests and diseases, and its mainly affected by the leaf surface properties and pesticide formulation properties. This article aims to investigate the wettability regulation mechanism and dynamic wetting properties of banana leaves, in order to intelligently design appropriate pesticide formulations. The micro-morphology of the banana leaves exhibits a micro-nano dual-scale structure with different microstructures and roughness on the adaxial side and abaxial side. Correspondingly, the wettability on the adaxial side of the banana leaf with higher roughness (Rq = 71.1 nm) is always better than that on the abaxial side (Rq = 42.5 nm). The droplet contact performance of droplets exhibits a strong concentration dependence of surfactants, which regulate the inter-species differences in the wettability of different pesticide formulations on both sides. Besides, the dynamic wetting process of pesticide droplets exhibits strong time dependence, by using a time series method to establish an AR(2) model, precise simulation and prediction of the contact angle changes on the adaxial side (R2 = 0.9560) and abaxial side (R2 = 0.8903) during the dynamic wetting process were achieved. The dynamic wetting model provides new insights into the spreading and deposition processes of droplets on leaves. This work provides a favorable reference for the study of the dynamic balance between wetting and adhesion properties of pesticide spray on leaf surfaces.

Transcriptomic profiling reveals histone acetylation-regulated genes involved in somatic embryogenesis in Arabidopsis thaliana

BackgroundSomatic embryogenesis (SE) exemplifies the unique developmental plasticity of plant cells. The regulatory processes, including epigenetic modifications controlling embryogenic reprogramming of cell transcriptome, have just started to be revealed.ResultsTo identify the genes of histone acetylation-regulated expression in SE, we analyzed global transcriptomes of Arabidopsis explants undergoing embryogenic induction in response to treatment with histone deacetylase inhibitor, trichostatin A (TSA). The TSA-induced and auxin (2,4-dichlorophenoxyacetic acid; 2,4-D)-induced transcriptomes were compared. RNA-seq results revealed the similarities of the TSA- and auxin-induced transcriptomic responses that involve extensive deregulation, mostly repression, of the majority of genes. Within the differentially expressed genes (DEGs), we identified the master regulators (transcription factors - TFs) of SE, genes involved in biosynthesis, signaling, and polar transport of auxin and NITRILASE-encoding genes of the function in indole-3-acetic acid (IAA) biosynthesis. TSA-upregulated TF genes of essential functions in auxin-induced SE, included LEC1/LEC2, FUS3, AGL15, MYB118, PHB, PHV, PLTs, and WUS/WOXs. The TSA-induced transcriptome revealed also extensive upregulation of stress-related genes, including those related to stress hormone biosynthesis. In line with transcriptomic data, TSA-induced explants accumulated salicylic acid (SA) and abscisic acid (ABA), suggesting the role of histone acetylation (Hac) in regulating stress hormone-related responses during SE induction. Since mostly the adaxial side of cotyledon explant contributes to SE induction, we also identified organ polarity-related genes responding to TSA treatment, including AIL7/PLT7, RGE1, LBD18, 40, HB32, CBF1, and ULT2. Analysis of the relevant mutants supported the role of polarity-related genes in SE induction.ConclusionThe study results provide a step forward in deciphering the epigenetic network controlling embryogenic transition in somatic cells of plants.

A 3-component module maintains sepal flatness in Arabidopsis

As in origami, morphogenesis in living systems heavily relies on tissue curving and folding through the interplay between biochemical and biomechanical cues. By contrast, certain organs maintain their flat posture over several days. Here, we identified a pathway that is required for the maintenance of organ flatness, taking the sepal, the outermost floral organ, in Arabidopsis as a model system. Through genetic, cellular, and mechanical approaches, our results demonstrate that the global gene expression regulator VERNALIZATION INDEPENDENCE 4 (VIP4) fine-tunes the mechanical properties of sepal cell walls and maintains balanced growth on both sides of the sepals, mainly by orchestrating the distribution pattern of AUXIN RESPONSE FACTOR 3 (ARF3). vip4 mutation results in softer cell walls and faster cell growth on the adaxial sepal side, which eventually cause sepals to bend outward. Downstream of VIP4, ARF3 works through modulating auxin to downregulate pectin methylesterase VANGUARD1, resulting in decreased cell wall stiffness. Thus, our work unravels a 3-component module that relates hormonal patterns to organ curvature and actively maintains sepal flatness during its growth.

Effect of light-induced changes in leaf anatomy on intercellular and cellular components of mesophyll resistance for CO2 in Fagus sylvatica.

Mesophyll resistance for CO2 diffusion (rm) is one of the main limitations for photosynthesis and plant growth. Breeding new varieties with lower rm requires knowledge of its distinct components. We tested new method for estimating the relative drawdowns of CO2 concentration (c) across hypostomatous leaves of Fagus sylvatica. This technique yields values of the ratio of the internal CO2 concentrations at the adaxial and abaxial leaf side, cd/cb, the drawdown in the intercellular air space (IAS), and intracellular drawdown between IAS and chloroplast stroma, cc/cbd. The method is based on carbon isotope composition of leaf dry matter and epicuticular wax isolated from upper and lower leaf sides. We investigated leaves from tree-canopy profile to analyse the effects of light and leaf anatomy on the drawdowns and partitioning of rm into its inter- (rIAS) and intracellular (rliq) components. Validity of the new method was tested by independent measurements of rm using conventional isotopic and gas exchange techniques. 73% of investigated leaves had adaxial epicuticular wax enriched in 13C compared to abaxial wax (by 0.50‰ on average), yielding 0.98 and 0.70 for average of cd/cb and cc/cbd, respectively. The rIAS to rliq proportion were 5.5:94.5% in sun-exposed and 14.8:85.2% in shaded leaves. cc dropped to less than half of the atmospheric value in the sunlit and to about two-thirds of it in shaded leaves. This method shows that rIAS is minor but not negligible part of rm and reflects leaf anatomy traits, i.e. leaf mass per area and thickness.

Morpho-anatomical studies of family lamiaceae species of district Lahore, Punjab: a revision to flora of Pakistan

BackgroundThis study was aimed to determine the taxonomic position and delimitation of fifteen Lamiaceae taxa using leaf epidermal morpho-anatomical features in Lahore. A main objective of the study was also the revision and upgradation of Lamiaceae taxa in the flora of Pakistan, as no details of studied species are found in the flora of Pakistan.MethodsThe examination of significant anatomical parameters, such as epidermal cell shape and size, stomatal types, guard and subsidiary cells shape and size, stomatal cavity size, trichome size and shape, oil droplets, crystals, and secretory cavity characteristics were studied using light microscopic (LM) and scanning electron microscopic (SEM) techniques. Among all the studied Lamiaceae species, these anatomical features varied significantly. Principal component analysis and correlation were done to distinguish the species’ similarities.ResultsMost species had pentagonal and hexagonal epidermal cells with straight anticlinal wall thickness. On the adaxial surface, paracytic stomata were found in Ocimum basilicum L. and Rosmarinus officinalis L. Diacytic stomata was observed in Ajuga reptans L. and anisocytic stomata in Galeopsis tetrahit L. In the abaxial surface, trichomes were present in five species, i.e., Mentha suaveolens Ehrh. A. reptans, Thymus vulgaris L., M. haplocalyx, and Salvia splendens Ewat. In S. splendens, peltate and glandular trichomes were seen whereas, in other species, trichomes were long, unbranched glandular and had tapering ends. In adaxial side trichomes were present only in M. suaveolens, A. reptans, S. bazyntina, O. basciculum, S. splendens, S. officinalis, S. rosemarinus. In other species, trichomes were absent on the adaxial surface. In abaxial view, M. suaveolens had the largest length of trichomes, and O. basciculum had the smallest. S. splendens L. had the largest trichome width, while T. vulgaris had the smallest.ConclusionHence, according to these findings, morpho-anatomical traits are useful for identifying Lamiaceae taxa. Also, there is a need of upgradation and addition of studied taxa in flora of Pakistan comprehensively.

Structure and Function of Blueberry Fruit and Flowers: Stomata, Transpiration and Photoassimilation

Blueberry (Vaccinium corymbosum L.) stands out among fruit in terms of three open physiological questions about its climacteric character, CO2 uptake, and the absence or presence of stomata on its floral organs. The objective of the present study was to examine the structures of blueberry flowers and fruit to explain their contribution to CO2 exchange and transpiration in order to clarify these discrepancies. Blueberries were dewaxed and the sepals/corolla removed for stomata counts, and their micromorphology was studied via LT-SEM. The fruit has stomata, contrary to beliefs in the literature, possibly because the stomata are occluded by the dense wax cover or ‘bloom’ and hidden on the distal part of the ovary in between and underneath the corolla. However, stomata were located on the distal part of the fruit surrounded by the sepals (calyx) and found predominantly on the abaxial sepals, while the adaxial side of the sepals and the proximal part of the ovary lacked stomata. The petals were devoid of stomata, trichomes, and chlorophyll and abscised after anthesis. In contrast, the sepals remained until maturity, contributing 5–7% to the berry surface but contributing to the majority of fruit stomata and chlorophyll. With 59–71% of the fruit’s chlorophyll, sepals were a significant source of the CO2 uptake. Similarly, with 95% of the berry stomata, sepals were a significant source of water loss, measured via porometry of fruit with and without sepals. Overall, this study identified the ovary as a minor source and sepals as the dominant source of CO2 and H2O exchange in blueberries.

Micromorphological and Chemical Characterization of Drimys winteri Leaf Surfaces: The Secondary Alcohols Forming Epicuticular Wax Crystals Are Accompanied by Alkanediol, Alkanetriol and Ketol Derivatives.

The cuticle is a hydrophobic coating of most aerial plant surfaces crucial for limiting non-stomatal water loss. Plant cuticles consist of the lipid polyester cutin and associated waxes with compositions varying widely between plant species and organs. Here, we aimed to provide a comparative analysis of the dark-glossy adaxial and pale-glaucous abaxial sides of Drimys winteri (Winteraceae) leaves. Scanning electron microscopy showed nanotubular wax crystals lining the entire abaxial side of the leaf (including stomatal pores), while the adaxial side had patches of mixed platelet/tubule crystals and smooth areas between them. Consecutive treatments for wax removal and cutin depolymerization revealed that the waxes were deposited on a cutin network with micron-scale cavities across the entire abaxial surface including the stomata pores, and on a microscopically smooth cutin surface on the adaxial side of the leaf. Gas chromatography coupled to mass spectrometry and flame ionization detection showed that the wax mixtures on both sides of the leaf were complex mixtures of very-long-chain compounds dominated by the secondary alcohol nonacosan-10-ol and alkanediols with one hydroxyl on C-10. It is therefore very likely that the characteristic tubular wax crystals of both leaf sides are formed by these alcohols and diols. Further secondary alcohols and alkanediols, as well as ketols and alkanetriols with one functional group on C-10, were identified based on mass spectral fragmentation patterns. The similarities between all these mid-chain-functionalized compounds suggest that they are derived from nonacosan-10-ol via regio-specific hydroxylation reactions, likely catalyzed by three P450-dependent monooxygenases with different regio-specificities.

Within-tree distribution and seasonal dynamics of Eutetranychus banksi and Euseius stipulatus (Acari: Tetranychidae, Phytoseiidae) on citrus: Implications for the biological control of the pest

The Texas citrus mite, Eutetranychus banksi (McGregor) (Acari: Tetranychidae), is a citrus pest widely distributed throughout the Americas and recently introduced in Spain. In this study we studied the within-tree distribution of E. banksi and the predatory phytoseiid mites, identify the phytoseiid species associated with the pest, and describe the seasonal trends to analyse the predator’s behaviour in response to the increase in pest density, allowing evaluation of biological control possibilities. The Texas citrus mite was mainly found on the adaxial (upper) side of leaves from the current year's shoots located at the periphery of the tree canopy, whereas phytoseiids prefer the abaxial (lower) side of leaves inside the tree canopy. The spider mite preferred to feed on leaves rather than fruits, whereas phytoseiids use both substrates equally. Eutetranychus banksi showed a single population peak in late summer-early autumn, while phytoseiids showed two peaks, a main spring peak and a second less abundant in autumn. The seasonal dynamics of E. banksi and phytoseiids on fruits occurred in parallel to those recorded on leaves. Euseius stipulatus (Athias-Henriot) was the most frequent and abundant phytoseiid species, apparently displacing other predatory mites. In autumn, when E. banksi reached high densities, phytoseiids moved from the leaf abaxial sides inside the tree canopy to the adaxial sides on the periphery and to the fruits, to feed on E. banksi. In addition, a change in phytoseiid colouration from white to reddish-brown was observed. Both, the number of red phytoseiids and their leaf occupation increased significantly in response to the prey population growth, which was indirect evidence of their contribution to the biological pest control. However, the low predator:prey ratios observed cannot avoid the pest population growth.

Characterization and Mapping of a Rolling Leaf Mutant Allele rlT73 on Chromosome 1BL of Wheat.

Leaf rolling is regarded as an important morphological trait in wheat breeding. Moderate leaf rolling is helpful to keep leaves upright and improve the photosynthesis of plants, leading to increased yield. However, studies on the identification of genomic regions/genes associated with rolling leaf have been reported less frequently in wheat. In this study, a rolling leaf mutant, T73, which has paired spikelets, dwarfism, and delayed heading traits, was obtained from a common wheat landrace through ethyl methanesulfonate mutagenesis. The rlT73 mutation caused an increase in the number of epidermal cells on the abaxial side and the shrinkage of bulliform cells on the adaxial side, leading to an adaxially rolling leaf phenotype. Genetic analysis showed that the rolling leaf phenotype was controlled by a single recessive gene. Further Wheat55K single nucleotide polymorphism array-based bulked segregant analysis and molecular marker mapping delimited rlT73 to a physical interval of 300.29-318.33 Mb on the chromosome arm 1BL in the Chinese Spring genome. We show that a point mutation at the miRNA165/166 binding site of the HD zipper class III transcription factor on 1BL altered its transcriptional level, which may be responsible for the rolling leaf phenotype. Our results suggest the important role of rlT73 in regulating wheat leaf development and the potential of miRNA-based gene regulation for crop trait improvement.

The PROLIB leaf radiative transfer model: Simulation of the dorsiventrality of leaves from visible to mid-wave infrared

Many plant species have dorsiventral leaves that have significant differences in optical properties from one side to the other. Several studies have revealed that ignoring this asymmetry induces significant errors in plant canopy reflectance, and current leaf models simulating leaf dorsiventrality are limited to the 0.4–2.5 μm wavelength range. This article, partly based on two recently collected datasets in the 2.5–14 μm wavelength range, demonstrates that ignoring leaf dorsiventrality induces significant errors in brightness temperature and effective emissivity at the canopy scale. The PROLIB model, which inherits from the PROSPECT-VISIR and LIBERTY models, is the first radiative transfer model to simulate the reflectance and transmittance of both leaf sides from 0.4 to 5.7 μm. The palisade and spongy mesophylls are represented as plate and sphere layers, respectively, to account for the structural asymmetry of leaf cells. The sieve effect that explains the differences in transmittance between the adaxial and abaxial sides of the leaf is successfully incorporated into PROLIB. Evaluation of the model on several leaf datasets shows that: (1) It reproduces well the adaxial and abaxial optical properties of the leaves, with a root mean square error (RMSE) of 0.0109 for reflectance and transmittance. (2) It can be inversed to retrieve leaf traits, with RMSE values for leaf chlorophyll, carotenoid, anthocyanin, water, and dry matter content of 5.519 μg/cm2, 2.344 μg/cm2, 4.219 μg/cm2, 0.0022 g/cm2, and 0.0017 g/cm2, respectively (corresponding normalized RMSE values of 22.0%, 34.0%, 49.4%, 19.6%, and 24.7%). However, better and more complete leaf datasets are needed for leaf dorsiventrality analysis and model calibration.

First Report of Powdery Mildew on Viburnum chinshanense Caused by Erysiphe pseudoviburni in China.

Viburnum chinshanense, a deciduous shrub in the family Caprifoliaceae, is a dominant tree distributed mainly in the North-Central and South-Central regions of China (Zhu et al. 2023). Because of its lush white flowers and vibrant red fruits, V. chinshanense is used widely as ornamental tree in China. In May 2022, severe powdery mildew symptoms were observed on V. chinshanense on the Huaxi Campus of Guizhou Normal University, Guiyang, China. The incidence was approximately 75% among 80 V. chinshanense plants observed. White mycelia were present on both adaxial and abaxial leaf sides, but not on fruits, petioles, or stems. Infected leaves showed slight chlorosis and twisting. The mycelia were amphigenous, forming small-to-large patches, often sparse on the upper leaf surface, but mostly confluent on the lower leaf surface. Hyphae were hyaline, 4-7 μm wide. Hyphal appressoria were lobed to multilobed, in opposite pairs or solitary. Conidiophores were erect, straight, or somewhat flexuous, 60-130 µm long (n = 30). Foot cells were subcylindrical to slightly curved-sinuous at the base, 20-40 × 6-10 µm (n = 30) in size, followed by 1-3 shorter cells. Conidia formed singly, occasionally two to three in a chain. Conidia were ellipsoid to ovoid, cylindrical, and 24-40 × 16-20 µm (n = 50). No fibrosin bodies were observed on the conidia. Chasmothecia were subglobose, 56-115 µm in diameter. The appendages were 35-70 µm long. Based on these morphological characteristics, the powdery mildew fungus was identified as Erysiphe pseudoviburni (Bradshaw et al. 2020). To confirm the identification, the ribosomal DNA internal transcribed spacer (ITS) and the ribosomal large subunit (LSU) region were amplified and sequenced using the ITS1/ITS4 primer pair (White et al. 1990) and the NL1/NL4 primer pair (Ziemiecki et al. 1990), respectively. The obtained 643-bp ITS sequence (GenBank accession no. ON729292) had 99.84% identity with E. pseudoviburni strains KUS-F27310 (MN431595) and MUMH0001 (LC009904). The obtained 593-bp LSU sequence (ON729293) had 99.83% identity with E. pseudoviburni (LC009904 and MN431595). Based on the phylogenetic analysis of the combined ITS and LSU dataset (Bradshaw et al. 2020), the isolate (GZVD-1) was grouped in a clade with the E. pseudoviburni strains KUS-F27319, KUS-F27310, and MUMH0001. To fulfill Koch's postulates, leaves of three healthy potted V. chinshanense plants were inoculated by gently pressing with diseased leaves. Non-contact plants were used as controls. All plants were incubated in a greenhouse at 25 ± 2°C, 80% relative humidity. Similar powdery mildew symptoms were observed on the inoculated plants 12 days after inoculation, whereas the control plants remained symptomless. The reisolated fungus from the inoculated plants was morphologically identical to that on originally diseased plants. ITS and LSU sequences of the reisolated fungus showed 100% identity with ON729292 and ON729293, respectively. E. pseudoviburni has previously been reported to infect some Viburnum species, including V. sieboldii in Japan (Takamatsu et al. 2015) and V. odoratissimum in South Korea (Bradshaw et al. 2020). To the best of our knowledge, this is the first report of powdery mildew caused by E. pseudoviburni on V. chinshanense in China. This work expands the known host range of E. pseudoviburni in the Viburnum genus.

Overlooked shell features: asymmetrical columellar folds in volutid gastropods

ABSTRACT Many gastropods have columellar folds, defined as continuous spiral ridges extending from the aperture to the shell interior on the adaxial side of the aperture. Despite their ubiquity, columellar folds have received little phylogenetic or functional study. In the vast majority of cases, columellar folds have a symmetrical profile, with the anterior (abapical) slope similar to the posterior (adapical) slope. Here I draw attention to the highly unusual phenomenon of asymmetry of columellar folds, where the anterior slope is markedly less inclined than the posterior slope of each fold. I have detected this condition in the volutid genera Scaphella Swainson, 1832; Cymbiola Swainson, 1831 and Lyrischapa Aldrich, 1911; as well as in the Palaeocene and Eocene genus Eovasum Douvillé, 1920. Following a review of Lyrischapa and Eovasum, I suggest that these two genera are closely related members of the volutid subfamily Indovolutinae, and that asymmetrical columellar folds have evolved three times in Volutidae. Although their function remains elusive, asymmetrical folds might prevent abapical displacement of the soft parts during rapid extension of the foot or feeding organs.

Exposure to Light of the Abaxial versus Adaxial Side of Detached Kalanchoë blossfeldiana Leaves Affects Anthocyanin Content and Composition Differently.

The accumulation and composition of anthocyanins in leaves of Kalanchoë blossfeldiana, detached and kept for five days under natural light conditions, were investigated. The presence of fifteen derivatives of cyanidin, petunidin, and delphinidin was found. Changes in the content of each anthocyanin in the leaves before and after exposure to light on the abaxial (naturally upper) and adaxial (naturally lower) sides of the leaves were compared. When the adaxial side was exposed to light, the anthocyanin contents of the leaves did not change. In contrast, when the abaxial side of detached leaves was exposed to light, there was enhanced accumulation of delphinidin-rhamnoside-glucoside, cyanidin-rhamnoside-glucoside, cyanidin-glucoside-glucoside, and two unknown derivatives of petunidin and delphinidin. Application of methyl jasmonate (JA-Me) on the abaxial side exposed to light inhibited the accumulation of these anthocyanins. This effect could probably be due to the presence of these anthocyanins in the epidermal cells of K. blossfeldiana leaves and was visible in the microscopic view of its cross-section. These anthocyanins were directly exposed to JA-Me, leading to inhibition of their formation and/or accumulation. The lack of significant effects of JA-Me on anthocyanin mono- and tri-glycosides may indicate that they are mainly present in the mesophyll tissue of the leaf.