Adaxial Side Research Articles

Morpho-anatomical features of the flower Tulipa biebersteiniana Schult. еt Schult. in the South of the Central Russian Upland

The processes of formation of many species are observed in the south of the Central Russian Upland. For these conditions, the morpho-anatomical features of the tepals of Tulipa biebersteiniana Schult. Et. Schult. fil as the adaptive potential of seed propagation were studied for the first time. The tepals are arranged in two circles and differ in morphological and anatomical features. Differences in the structure of the main cells of the epidermis on the abaxial and adaxial sides were revealed. On the abaxial side, the main epidermal cells are rectangular, sometimes fusiform or rarely diamond-shaped, arranged in rows. They are covered with a weakly longitudinally wrinkled cuticle. The side walls of the abaxial surface are straight or slightly curved. On the adaxial surface, the side walls are zigzag, passing to the lateral edge in strongly sinuous. The localization, estimated functions and sizes of the hairs on the leaves of the tulip were determined. Single celled trichomes are located in two places.

Stomata Profile Comparisons in Abaxial and Adaxial Zones of Dendrobium aphyllum and Arachnis flos-aeris Leaves

Stomata play an essential role in transpiration and metabolism. Orchids are Crassulacean Acid Metabolism (CAM) plants which are generally succulent leaf type. Orchids have several types of stomata, depending on habitat and environmental parameters that affect them. This study aimed to compare the stomata, including the anatomical structure, activity, and density of the orchids Dendrobium aphyllum and Arachnis flos-aeris. The method used was printing the surface of the leaves using glue and observed with a microscope. Data obtained were analyzed with the help of Image raster 3.0 and MS. Excel. In the present study, the stomata of D. aphyllum and A. flos-aeris are characterized by anomocytic type. The highest stomata density was obtained on the abaxial part of D. aphyllum 09.00 am 1177.78 um2. The adaxial leaves of both species are classified as low, or no stomata are found at all. The distance between the stomata on the abaxial leaves of D. aphyllum and A. flos-aeris is denser than the leaves' adaxial side. Stomata activity in orchids is related to orchids' adaptation process to the environmental parameters of their habitat. Stomata activity affects the transpiration process and CO2 fixation in orchid CAM metabolism.

Anatomical Structure of Polygonatum Mill. Species in the Precarpathian Region

Polygonatum Mill. species are found in woods of the temperate zone of the Northern Hemisphere. There are four species growing in Ukraine, the most common of which is Polygonatum multiflorum (L.) All. In forest and shrub habitats are also widespread Polygonatum odoratum (Mill.) Druce., Polygonatum latifolium Desf. and Polygonatum verticillаtum (L.) All. Polygonatum species have rhizomes of the sympodial type. They are of a primary anatomical structure. In the primary growth of the stem, as well as rhizomes, there is the central cylinder (stele) and the cortex. The structure of the leaf blade is related to the performance of basic functions: photosynthesis, respiration and transpiration. The leaves are isolateral with a lighter adaxial and shaded abaxial sides. The leaf is covered with epidermis. Beneath the epidermis is chlorenchyma, which makes up the leaf pulp - mesophyll.
 The microscopic structure of Polygonatum multiflorum (L.) All. was studied. The anatomic description includes the characteristic of rhizomes, leaves and stems structure.

Presence of Powdery Mildew Caused by Erysiphe corylacearum on Hazelnut (Corylus avellana) in Italy.

Hazelnut (Corylus avellana) is widely grown in Italy, which is the second largest producer worldwide with 132,700 tonnes harvested from 78,593 hectares (FAOSTAT, 2018 ). Powdery mildew caused by Phyllactinia guttata has been reported in Italy and in other European countries, but recently in Austria, Switzerland and in central Europe a new species was discovered (Voglmayr et al., 2020; Beenken, 2020). During summer 2020, in Villar Fioccardo (Torino province, Piedmont, Italy) on hazelnut (cv. 'Tonda Gentile') growing on the edges of private gardens and parks, an extensive colonization of the adaxial side of the leaves with white powdery mycelium covering more than 80% of the surface was observed. Also, the abaxial side of the leaves showed the scattered presence of powdery, white, and thin mycelium. The powdery fungal pathogen collected from leaves had amphigenous, hyaline, branched, septate 1.5 to 3.7 μm wide mycelium; lobed, solitary hyphal appressoria; vertically elevated above the mycelium 53 to 82 μm long and 5 to 12 μm wide conidiophores (n = 30); hyaline, ellipsoid, ovoid to doliform conidia, solitary on conidiophores, 21 to 36 μm long, 15 to 21 μm wide (average 28 to 18 μm) (n = 50). Chasmothecia appeared in late September 2020 and they were spherical, single or in groups, 83 to 138 (average 100) μm in diameter (n = 50); 7 to 15 aseptate appendages were straight, sometimes flexuous, 55 to 111 (average 73) μm long (n = 50), with four to five times dichotomous branched apexes and recurved tips. In each chasmothecium, there were three to five ellipsoid, ovoid to subglobose asci with a length of 41 to 60 μm and a width of 28 to 56 μm (average 52 to 44 μm) (n = 30). Asci contained four to eight ascospores, 15 to 26 μm long and 10 to 17 μm wide (average 19 to 12 μm) (n =50). Mycelia were carefully scraped from the leaves with a scalpel and DNA was extracted by using the E.Z.N.A. Fungal DNA Mini Kit (Omega Bio-Tek, Darmstadt, Germany). Partial rDNA internal transcribed spacer region (ITS) of two isolates (DB20SET01, DB20SET01) was amplified using specific primers PMITS1/PMITS2 (Cunnington et al. 2003) and sequenced. Obtained sequences were deposited in GenBank (Accession Nos. MW045425, MW045426). BLAST analysis of the obtained 749-bp fragments showed 100% identity to ITS rDNA sequences of Erysiphe corylacearum from Switzerland (MN822721) and Azerbaijan (LC270863). One-year-old plants of C. avellane cv. Tonda Gentile were artificially inocuated by dusting conidia from infected leaves. Inoculated plants were incubated under controlled conditions at 23°C ± 1 and 70 to 80% relative humidity. Typical symptoms (white bloom) appeared on the upper surface of the leaves at 8 to 10 days after inoculation. No symptoms were found on control plants treated with sterile water. The fungus isolated from inoculated leaves was morphologically identical to the original isolates from diseased plants collected from Villar Fioccardo. Erysiphe corylacearum causes a new and aggressive form of powdery mildew. Since the first observation in north-eastern Turkey in 2013, it has spread rapidly throughout the Black Sea region, causing significant economic losses (Sezer et al., 2017). It has also been reported in Iran, Azerbaijan, and Ukraine (Arzanlou et al. 2018; Heluta et al., 2018). The disease has been observed sporadically in Piedmont, Italy, during summer 2020 (Regione Piemonte & Agrion, 2020) in some hazelnut growing areas, but presently, doesn't appear to impact yield. This is the first report of E. corylacearum, causing an aggressive powdery mildew on hazelnut in Italy, and as such, may more severely affect hazelnut groves in Italy and cause considerable yield losses. Literature cited Arzanlou M et al. 2018. Forest Pathology, 48:e12450. https://doi.org/10.1111/efp.12450. Beenken L et al. 2020. New Disease Reports 41, 11. http://dx.doi.org/10.5197/j.2044-0588.2020.041.011. Cunnington JH et al. 2003. Australasian Plant Pathology, 32, 421-428. Food and Agriculture Organization (FAO). 2018. http://www.fao.org/faostat/en/#home Heluta V.P. et al.2019. Ukrainian Botanical Journal, 2019, 76(3), 252-259. Regione Piemonte SFR & Agrion. 2020. https://www.regione.piemonte.it/web/sites/default/files/media/documenti/2020-10/mal_bianco_nocciolo_da_erysiphe_corylacearum.pdf Sezer AD et al. 2017. Phytoparasitica, 45, 577-581. Voglmayr H et al. 2020. New Disease Reports, 42, 14 http://dx.doi.org/10.5197/j.2044-0588.2020.042.014.

Augmented phytotoxic effect of nanoencapsulated ophiobolin A

Ophiobolin A is a secondary phytotoxic metabolite produced by some pathogenic fungal species responsible for severe plant diseases, considered to play a role in disease development and symptom appearance. Herein we investigated whether the phytotoxic activities of ophiobolin A against weed species could be improved by nanoencapsulation. Given the rapid natural degradation of the compound, it was hoped that nanoencapsulation would prolong the phytotoxic effects or enhance the bioactivity, thus leading to improved weed control capabilities. This article presents an assessment of the effectiveness of encapsulated ophiobolin A on 11 commonly found weed species, compared to the pure ophiobolin, to the particle alone, and a combination of mixed particles and ophiobolin A, by applying the solution droplets to both intact or injured leaf surface, on the adaxial or abaxial side. The bioassays showed the improved efficacy of the encapsulated ophiobolin, and the need for leaf lesions to diffuse the particles into the tissues.

SAW homeodomain transcription factors regulate initiation of leaf margin serrations.

Plant leaves are the main photosynthetic organ of plants and they occur in an array of different shapes. Leaf shape is determined by morphogenesis whereby patterning of the leaf margin can result in interspaced leaf serrations, lobes, or leaflets, depending on the species, developmental stage, and in some instances the environment. In Arabidopsis, mutations in the homeodomain transcription factors SAW1 and SAW2 result in more prominent leaf margin serrations. Here we show that serrations appear precociously in the saw1 saw2 mutant. The pattern of auxin maxima, and of PIN1 and CUC2 expression, which form a feedback loop that drives serration outgrowth, is altered in saw1 saw2 and correlates with precocious serration initiation. SAW1 is not expressed in the outer epidermal cell layer where PIN1 convergence points generate auxin maxima. Instead, SAW1 is expressed on the adaxial side of the leaf and expression in this domain is sufficient for function. We suggest that SAW1 and SAW2 repress serration initiation and outgrowth by promoting the transition to a determinate fate in the leaf margin.

Evaluation of Factors Affecting Direct Organogenesis in a Somatic Tissue Culture of Sinningia speciosa (Lodd.) Hiern

In this study, the influence of genotype, concentration of thidiazuron (TDZ), and explant position on the culture medium in organogenesis in a somatic tissue culture of two gloxinia cultivars was investigated. Isolated explants cultured on the medium containing TDZ formed adventitious shoots directly without an intervening callus phase. Explant regeneration frequency varied depending on the genotype, TDZ concentration, and explant position on the medium. The analysis of variance revealed that cultivar (C), TDZ concentration (T), position of explant on culture medium (P), and the interaction of C × T, C × P, T × P, and C × T × P significantly influenced the frequency of shoot formation. However, the effect of interface C × P and C × T × P on the number of shoots per explant was not significant. “Snowy” leaf explants manifested a significantly higher mean shoot formation frequency (p ˂ 0.01) in comparison with the cultivar “Midnight Purple”. The medium enriched with 3.5 μM TDZ resulted in the highest organogenesis frequency, while the highest shoot number per explant was acquired on medium supplemented with 4.0 μM TDZ. The explants of the tested cultivars cultured on the medium with the adaxial side down showed a significantly higher (p ˂ 0.01) shoot formation frequency in comparison with explants cultured on the medium with the abaxial side, and they showed a higher mean number of shoots per explant. An effective method for in vitro organogenesis of Sinningia speciosa (Lodd.) Hiern without an intervening callus phase was established.

Leaf age is important for assessment of resistance in chrysanthemum against Frankliniella occidentalis

Feeding behaviour of pest insects on host plants depends on the plant morphology and chemical composition. So far, leaf position was demonstrated important for estimation of thrips resistance in Capsicum, where resistant associations showed a higher resistance in the youngest leaves compared to old leaves. In the current study, the feeding behaviour of female Frankliniella occidentalis, a major pest of chrysanthemum, and the egg-laying activity was assessed in a non-choice experiment in the climate chamber. We hypothesize that the physiological status, i.e. the age of chrysanthemum leaves, is an important resistance factor influencing thrips silver damage and the number of offspring. In general, the results show significantly higher feeding damage on old (basal) leaves of susceptible cultivars compared to resistant cultivars on the abaxial side of the leaf. In contrast, we detected no significant differences on the adaxial side of the leaves neither for old nor for young leaves. However, feeding damage on different leaf positions is an important factor for resistance level determination. Additionally, we detected significant differences in reproductive activity, i.e. number of hatched larvae on old leaves compared to young leaves for all cultivars. Overall, on old leaves we detected more larvae. The comparison between the old leaves of all cultivars exhibited a significant difference between one resistant and one susceptible cultivar. Contrary to that, the comparison between the young leaves of all cultivars exhibited no significant differences. All findings are important for advancing future resistance screenings in chrysanthemum.

Study of infection process of five species of Colletotrichum comparing symptoms of glomerella leaf spot and bitter rot in two apple cultivars

Bitter rot (BR) and glomerella leaf spot (GLS) occur in all the Brazilian South orchards with different species frequency per region. The main species found in Brazil belong to the Colletotrichum acutatum complex (Cac) and to the C. gloeosporioides complex (Cgc). The objectives of this study were to evaluate the favorable conditions for the germination and growth of five Colletotrichum species and, to compare pathogenicity and aggressiveness among species and between two apple cultivars in fruit, causing BR, and in leaves, causing GLS. The highest germination of conidia (above 90%) was achieved between 15 and 30 °C for Cgc species while for Cac species the highest germination (mean of 71%) was at 25 °C. The optimal temperature for mycelial growth did not differ between complexes and ranged from 23 to 27 °C. Althought, Cgc had a higher estimated maximum temperature then Cac. C. siamense cause BR symptoms regardless of cultivar or type of inoculation. C. nymphaeae and C. melonis caused symptoms in wounded and unwounded fruit but for C. paranaense and C. fructicola the symptoms were observed only in wounded fruit. Leaf symptoms of GLS was more severe in stressed leaves inoculated on the abaxial side compared to non-stressed leaves inoculated on the adaxial side. C. fructicola and C. nymphaeae were able to cause GLS symptoms in leaves with severity varying from 17.5 to 25% (cv. Gala). C. fructicola was the most severe causing GLS symptoms in cv. Gala (severity around 20.5%) and, in cv. Eva (severity around 11%). We discuss the roles that each species plays as a pathogen to better understand BR and GLS in different orchards conditions.

Leaf blade anatomy of the rare Siberian flora species Mertensia sibirica (L.) G. Don fil. (Boraginaceae)

The authors present the findings of a leaf blade anatomy study for the rare relict Siberian flora species Mertensia sibirica (L.) G. Don fil. (Boraginaceae). They collected samples for the study from natural habitats in Chita Region (Chikoy Range) and then planted them in the introduction area of the Siberian Botanic Garden (Tomsk) located in the southern taiga subzone of Western Siberia. The parameters of the photosynthetic and stomatal complex of M. sibirica were studied for the first time. It was found out that the rosette and cauline leaves of the species under study are hypostomatous, with an anomocytic stomatal complex. The epidermis is single-layer. On average, the adaxial epidermis has larger cells vs. abaxial epidermis. The leaf mesophyll is 242.90–369.90 µm thick, dorsiventral. The adaxial side of the leaf comprises glandular trichomes surrounded with pronounced rosettes of cells in the base part. The cauline leaf significantly differs from the rosette leaf in finer cells of its adaxial and abaxial epidermis (and, consequently, their larger number per 1 mm2), while the adaxial epidermal cells are thicker, and in a larger number of stomata in the abaxial epidermis. The palisade mesophyll in the cauline leaf is more developed vs. the rosette leaf, while the cells are longer and the palisade/spongy mesophyll ratio is higher. The rosette leaves have a more developed system of vascular tissues vs. cauline ones, as they play the main role in providing plants with water and nutrients. The contribution of the cauline leaf palisade mesophyll to the photosynthetic potential of M. sibirica is higher vs. that of the rosette leaf (the ratio between palisade and spongy mesophyll is 0.45 vs. 0.36, respectively), which characterizes the cauline leaf as more heliophytic. The stomatal complex and mesophyll parameters under study are primarily characterized by low variance. As for dermal tissue parameters, medium variance is typical of the thickness and size of the abaxial and adaxial epidermal cells. Coefficients of variation for the cells of the upper mesophyll layer (CV=31.2–41.6%) and the number of stomata on the lower epidermis of the rosette leaf (CV=21.5%) demonstrate medium and high variance. A very high coefficient of variation (116.2–174.0) is registered for the adaxial epidermis parameter characterizing the density of trichomes per 1 mm2. The study results were used to develop an optimal M. sibirica cultivation regime under conditions of introduction in the southern taiga subzone of Western Siberia.

Extracellular ice formation in special intercellular air spaces in Stachys byzantina C. Koch

In the present study, the sites of extracellular ice formation within leaves and petioles of Stachys byzantina C. Koch were identified and anatomically studied by different imaging techniques. Naturally acclimated plant parts were analyzed during the winter season in various states (fixed, native, before freezing, frozen and after thawing) by using digital microscopy, cryo scanning electron microscopy or via µ‐CT. Besides ice bodies occurring in normal intercellular spaces within the mesophyll, larger ice accumulations developed at special sites close to the vascular bundle of the petiole and the adaxial leaf veins. At those sites, ice accumulated in mainly four continuous intercellular spaces, which are reversibly expandable. In those spaces, various “connective zones” allowed the cells to remain connected during the freezing process. Two of these large intercellular spaces are located on the abaxial side, the other two on the adaxial side. This symmetrical arrangement continues into the petiole. Due to the dehydrating effect of extracellular ice formation, the living tissue showed considerable shrinkage during freezing. However, almost no freezing induced wilting could be detected, probably due to the stabilizing effect of collenchyma and lignified vascular tissue.

Transcription of the WUSCHEL-RELATED HOMEOBOX 4 gene in Arabidopsis thaliana

Phylogenetic shadowing and chromatin accessibility data suggested that essential regulatory elements are absent in the 2.9 kb immediate upstream region of the published WOX4pro::YFP cambium marker. Inclusion of an additional 6.3 kb of upstream promoter sequence and confocal imaging with different fluorophores in transgenic Arabidopsis lines revealed a much wider cell-type-specific expression pattern in parenchymous cells of the aerial plant body. The previously demonstrated activity of the WOX4pro::YFP marker in the cambium of vascular strands in the young Arabidopsis inflorescence stem depicts only sectors of a circular subcortical layer of parenchymous AtWOX4-positive cells. Transcription starts in subepidermal cells within the inflorescence apex in a phyllotactic pattern and extends into successively branching lateral organs, which are connected via small tube-like domains of AtWOX4-expressing cells with the circular subcortical parenchymal layer that extends basipetally down the stem. AtWOX4 expression is most dynamic in leaves, where promoter activity is observed transiently at the adaxial side of the lamina and remains detectable later in the palisade parenchyma, although at a weaker level than in the vasculature. In the root the extended AtWOX4 promoter is active through the proximal root meristem, i.e. in the quiescent centre (QC) and its surrounding initials, a pattern that is broader than transcription of its stem cell promoting relative AtWOX5 in the QC. Outside the proximal meristem AtWOX4 transcription is observed in upper cell layers of the columella root cap beneath or above within the stele in proto- and metaxylem cells, in a ribbon-type pattern which divides the central cylinder in two equal halves. This xylem-specific expression it the root stele relates to established AtWOX4 activity in xylem parenchyma specificity within vascular bundles of the stem.

First Report on the Occurrence of an Aggressive Pathotype, 734, of Plasmopara halstedii Causing Sunflower Downy Mildew in Hungary.

Downy mildew of sunflower (Helianthus annuus L.) is caused by Plasmopara halstedii (Farl.) Berl. et de Toni, leading to significant losses in crop production worldwide. The number of new and more aggressive pathotypes has increased rapidly over the last 10 years in Europe (Virányi et al. 2015, Bán et al. 2018), therefore, constantly monitoring the distribution of races is an important task. As part of regular surveys in June 2019, severe downy mildew was identified in some regions, appearing as chlorotic lesions along the veins of the adaxial side and white sporulation on the abaxial side of the leaves of severely stunted hybrids containing PI6 and PI7 resistance genes. The identification of the pathogen was performed microscopically based on morphological characteristics (average size of sporangia: 28x20 µm). Disease incidence (the ratio of diseased plants) ranged between 10 and 30% per field in three regions and resulted in moderate yield loss. Isolates (defined as a lesion per leaf) were collected from 4 to 8 infected leaves of each hybrid by region and stored at -70°C. Two, one and one isolates of P. halstedii were selected and characterized from the southeastern (Békés County), northern (Nógrád County) and northeastern (Borsod-Abaúj-Zemplén County) regions of Hungary, respectively. The pathotype of the four isolates was determined using the international standardized nomenclature method reviewed by Trojanová et al. (2017), including nine sunflower differential inbred lines (HA-304, RHA-265, RHA-274, PMI-3, PM-17, 803-1, HAR-4, QHP2 and HA-335). Zoosporangia from frozen sunflower leaves were washed off into bidistilled water and the concentration was adjusted to 3.5x104 sporangia/ml using a hemocytometer. Three-day-old seedlings with a radical of 1 to 1.5 cm long were immersed in the sporangial suspension and kept at 16°C overnight (Cohen and Sackston 1973). Inoculated seedlings were planted into trays containing clear moistened perlite (d = 4 mm) and grown in a growth chamber with a photoperiod of 12 h. The experiment was carried out twice with each isolate using 15 seeds/differential line with two replicates. Bidistilled water was sprayed on the plants 9 days after inoculation, and then trays were covered with a black polyethylene bag and maintained at 19°C overnight to induce sporulation. The first disease assessment was done based on cotyledons bearing white sporulation. Next, a second evaluation was performed 21 days after inoculation assessing stunting of the plants, chlorotic lesions on true leaves and damping-off. All 4 isolates examined caused disease on differential lines HA-304, RHA-265, RHA-274, PMI-3, PM-17 and HA-335, whereas the other lines showed no symptoms and signs of sunflower downy mildew. As a result, it was concluded that the presence of P. halstedii pathotype 734 was confirmed. This pathotype is likely widespread in Hungary as it could be detected from three different regions. Moreover, the possibility that pathotype 734 is present in Hungary has been raised before (Iwebor et al. 2018). This pathotype is already widespread in the USA and Russia and is considered to be highly aggressive, since it was able to infect hybrids with resistance genes PI6 and PI7 (Iwebor et al. 2018, Spring 2019). To our knowledge, this is the first report of pathotype 734 of P. halstedii in Hungary and Central Europe. Continuous monitoring and incorporation of new resistance genes into sunflower hybrids are essential steps in the future to control P. halstedii.

Floral structure inThismia(Thismiaceae: Dioscoreales): new insights from anatomy, vasculature and development

AbstractThismia is characterized by an exceptionally complicated floral morphology that is currently not understood properly. In the taxonomic literature, descriptive rather than morphological terms are often applied to parts of the flower in Thismia, relating to the general appearance of the floral organs instead of their precise homologies. Precise understanding of the floral structure is complicated by the rarity of Thismia spp. and the paucity of appropriate material. Here we provide a comprehensive study of reproductive organs of three Thismia spp. (T. annamensis, T. javanica and T. mucronata) including the first investigation of inflorescence architecture and early floral development in Thismiaceae. We found a hitherto unknown diversity of the reproductive shoots in the genus, manifested in the number of floral prophylls (two or three, in contrast to a single prophyll in the vast majority of monocots) and in the branching plane resulting in two distinct inflorescence types, a drepanium and a bostryx. We report the non-acropetal sequence of initiation of floral whorls (with stamens being the last elements to initiate), never previously described in monocots, and the gynoecium composed of completely plicate carpels, also a rare feature for monocots. Floral vasculature is relatively uniform in Thismia, but significant interspecific differences are found in tepal innervation, including the number of tepal traces; some of these differences are not immediately related to the external tepal morphology. We argue that the annulus, which acts as a roof of the hypanthium, possesses an androecium nature and represents congenitally fused bases of stamen filaments. We describe the stamens as laminar structures, which are also shortly tubular in the distal part of the supraconnective with the adaxial tubular side forming a skirt-like appendage. Finally, the placentas, which are column-like when mature, are initially parietal, becoming secondarily similar to free-central placentas through schizogenous separation from the ovary wall.

Differential Distribution of Flavonoids and Phenolic Acids in Leaves of Kalanchoe delagoensis Ecklon & Zeyher (Crassulaceae).

Kalanchoe delagoensis is adapted to intense solar irradiation, drought, and heat, partially due to the presence of phenols, important photo-protective compounds and antioxidants. This study aimed to evaluate the distribution of flavonoids and phenolic acid derivatives throughout the erect-tubular leaves of K. delagoensis. Specimens grown under sunny conditions were used for histochemical and high-performance liquid chromatography coupled with diode array detection (liquid HPLC-DAD) analysis. The NP (2-aminoethyl diphenylborinate) test suggested the presence of phenolic acids throughout the leaf blade below the epidermis and in chloroplasts, mainly in the leaf base. Flavonoids were detected specifically in chloroplasts, on the adaxial side of the middle third and at the leaf apex, near the meristematic cells. There was a tendency of flavonoid accumulation from the middle third to the apex, especially surrounding the gem, while phenolic acids were observed mainly in the base. This can be explained by the more exposed leaf apex and to the presence of apical buds (high production and regulation sites of ROS). The HPLC-DAD analysis showed different classes of flavonoids and phenolic acid derivatives in the leaf extracts, agreeing with the NP test results. This is the first time that the substitution of phenolic acids by flavonoids from the leaf base to the apex has been described.

Chemical profiles of cuticular waxes on various organs of Sorghum bicolor and their antifungal activities

Sorghum bicolor is widely cultivated in arid and semi-arid areas. This paper reports the chemical profiles of cuticular waxes on adaxial and abaxial sides of common leaf, flag leaf, sheath and stem from six sorghum cultivars and the variations of leaf cuticular waxes at seedling, jointing and filling stages. Then, the bioassay of leaf and sheath wax were evaluated against Penicillium sp and Alternaria alternata. The six sorghum cultivars had similar wax profiles. In total, eight wax compounds were identified, including fatty acids, aldehydes, primary alcohols, alkanes, secondary alcohols, ketones, sterols and minor triterpenoids. Leaf wax coverage increased from 2.2 to 3.1 μg/cm2 at seedling stages to 6.5–14.0 μg/cm2 at jointing and filling stages, respectively. The relative abundance of primary alcohols decreased from 51 to 62% at seedling stage to 17–33% at jointing stage whereas alkanes increased from 5-9% to 19–33%. Leaf was dominated with alkanes (28.4%) and aldehydes (28.4%), sheath with acids (42.8%), and stem with aldehydes (80.8%). Epicuticular wax of leaf and sheath contained higher proportions of alkanes whereas the intracuticular waxes contained higher proportions of sterols. The leaf wax improved the growth of Penicillium but reduced that of A. alternaria, whereas sheath wax reduced the growth of Penicillium but unchanged A. alternaria. The detailed sorghum wax profiles improve our understanding of the physiological roles of these waxes and their diversified potential usages in industries.

Advanced Microtexture Study of Anacardium occidentale L. Leaf Surface From the Amazon by Fractal Theory.

This work applies stereometric parameters and fractal theory to characterize the structural complexity of the 3D surface roughness of Anacardium occidentale L. leaf using atomic force microscopy (AFM) measurements. Surface roughness was studied by AFM in tapping mode, in air, on square areas of 6,400 and 10,000 μm2. The stereometric analyses using MountainsMap Premium and WSXM software provided detailed information on the 3D surface topography of the samples. These data showed that the morphology of the abaxial and adaxial side of the cashew leaf is different, which was also observed in relation to their microtextures. Fractal analysis showed that the adaxial and abaxial sides have strong microtexture homogeneity, but the adaxial side presented higher surface entropy. These results show that image processing associated with fractal theory can be an indispensable tool for identifying plant species by their leaves because this species has singularities on each side of the leaf.

Suppression of B function by chimeric repressor gene-silencing technology (CRES-T) reduces the petaloid tepal identity in transgenic Lilium sp.

Some monocotyledonous plants, including liliaceous, amaryllidaceous and iridaceous ones, produce flowers with petaloid tepals in whorls 1 and 2 organs. For explaining the molecular mechanism of two-layered petaloid tepal development, the modified ABC model has been proposed, in which B class genes are expressed in whorl 1 organs as well as in whorls 2 and 3 organs. We have previously obtained results strongly support the modified ABC model by chimeric repressor gene-silencing technology (CRES-T)-mediated suppression of B function in the liliaceous plant Tricyrtis sp. In the present study, we introduced a CRES-T construct derived from the B class gene of Tricyrtis sp. (TrihDEFa-SRDX) into Lilium sp. in order to examine the effect of suppressing B function on the floral organ identity. Flowers of transgenic plants did not open fully and had pale pink-colored tepals with decreased numbers of papillae on the adaxial side in whorls 1 and 2 compared with those of non-transgenic plants. No apparent morphological alterations were observed in whorls 3 and 4 organs. Both the amount of total anthocyanins and the expression levels of endogenous flavonoid biosynthesis-related genes (LhMYB12, LhbHLH2, LhCHS, LhF3H, LhF3’H, LhDFR and LhANS) decreased in whorls 1 and 2 organs of transgenic plants compared with non-transgenic plants. In addition, the expression levels of endogenous B class genes (LFDEF, LFGLOA and LFGLOB) decreased in transgenic plants and the level was negatively correlated with the degree of morphological alteration. Thus suppression of B function may reduce the identity of petaloid tepals in whorls 1 and 2 of transgenic Lilium sp.

Anatomia foliar de biótipos de Conyza sumatrensis suscetível e resistente ao glifosato

Conyza sumatrensis é uma planta daninha que apresenta resistência ao herbicida glifosato. A resistência pode ser devido a diferenças anatômicas entre biótipos resistentes e suscetíveis ao herbicida. O objetivo deste trabalho foi realizar a descrição anatômica da folha de biótipos de Conyza sumatrensis resistentes e suscetível ao herbicida glifosato, com vistas a identificar possíveis alterações que possam influenciar a absorção e/ou a translocação do herbicida. Para tanto, foram coletadas folhas de dois biótipos resistentes e um suscetível ao glifosato e fixadas em FAA 70 e, posteriormente, em etanol 70. Foram realizadas a determinação da espessura da epiderme na face adaxial das folhas, diâmetro dos feixes vasculares, além do índice e densidade estomática. As análises histológicas foram realizadas utilizando-se microscópio óptico, sendo tomadas fotografias de, no mínimo, quatro leituras em cada lâmina. Os resultados observados na caracterização da epiderme adaxial e do diâmetro dos feixes vasculares, não apresentaram diferenças entre os biótipos resistente e suscetível. Por outro lado, o biótipo suscetível apresenta maior densidade e índice estomático quando comparado aos demais, podendo estar relacionado com a suscetibilidade ao herbicida glifosato entre os materiais.

Synergistic Interaction of Phytohormones in Determining Leaf Angle in Crops.

Leaf angle (LA), defined as the angle between the plant stem and leaf adaxial side of the blade, generally shapes the plant architecture into a loosen or dense structure, and thus influences the light interception and competition between neighboring plants in natural settings, ultimately contributing to the crop yield and productivity. It has been elucidated that brassinosteroid (BR) plays a dominant role in determining LA, and other phytohormones also positively or negatively participate in regulating LA. Accumulating evidences have revealed that these phytohormones interact with each other in modulating various biological processes. However, the comprehensive discussion of how the phytohormones and their interaction involved in shaping LA is relatively lack. Here, we intend to summarize the advances in the LA regulation mediated by the phytohormones and their crosstalk in different plant species, mainly in rice and maize, hopefully providing further insights into the genetic manipulation of LA trait in crop breeding and improvement in regarding to overcoming the challenge from the continuous demands for food under limited arable land area.