Variations in epidermal trichomes of a mystic weed Parthenium hysterophorus L. from semi-arid regions of Barmer, Rajasthan (India).

This study for the first time examined foliar epidermal anatomical characteristics (Epidermal cells, types of stomata and trichomes) of thirteen Artemisia species (Including rare ones) with Light microscopy (LM) and Scanning electron microscopy (SEM) from the Northeast (Gilgit-Baltistan) region of Pakistan. The epidermal cells varied from polygonal to irregular and elongate in shape, while wavy to smooth in margins. This investigation revealed four different types of stomata viz; Anomocytic, diacytic, anomotetracytic and anisocytic, which were unequally scattered on both the adaxial and abaxial surfaces of studied Artemisia species. Ten different types of trichomes were observed in the studied species. Four types of glandular trichomes including peltate, pluricellular, capitate and thin necked were observed, whereas six types of nonglandular trichomes including, Aduncate, unicellular calavate, conical type, stinging hair type, unicellular tector and unicellurar filiform were observed. This study authenticated that the morphology of these foliar anatomical characteristics in amalgamation with other features are helpful for the species delimitation within the genus Artemisia.

The structure, micromorphology and distribution of trichomes on <i>Dracocephalum moldavicum</i> L. shots were investigated using light and scanning electron microscopy (SEM). There were distinguished 3 types of non-glandular trichomes, 3 types of glandular trichomes and papillae of the osmophore in the epidermis of the corolla. The highest density of non-glandular and glandular trichomes was found on the abaxial surface of the calyx, on bracts and in the upper part of the stem. Structural variations in the head and stalk of long glandular trichomes were demonstrated. The dimensions of particular types of trichomes are given in the present paper. Differences in the structure of the trichomes of this species are presented, compared to literature data. The micromorphology of particular trichome types is documented in numerous photographs showing the rich ornamentation of the cuticle of non-glandular trichomes.

Extracts of different polarities were obtained from plants of Lavandula stoechas subsp. luisieri and Lavandula pedunculata collected in the Center and Southwest Portugal. In order to have an idea on the possible classes of compounds present in each extract, they were subjected to a preliminary phytochemical screening through thin layer chromatography on silica gel plates, developed in appropriated mixtures of eluents and revealed with the specific reagents. Both taxa showed a hydrophilic and lipophilic chemical composition, being more diverse in L. stoechas subsp. luisieri. The micromorphology and histochemistry of secretory structures were also investigated by light and scanning electron microscopy. The common types of glandular trichomes, found in the Lamiaceae, peltate and capitate type I and II, were identified in each species as well as non-glandular stellate trichomes. In addition to these, L. pedunculata also presented capitate type III trichomes and still more two types of secretory trichomes: i) stellate type with both glandular and non glandular arms and ii) another type of capitate trichome, with a long and broad stalk formed by 2 cells, the basal is conical and much larger than the second, this similar to a ring, which supports a pluricelular head. These types of trichomes appear in the leaves but predominate in the flowers. The histochemical tests confirmed the existence of hydrophilic and lipophilic metabolites in glandular trichomes, except in the peltate hairs of the leaves of L. stoechas subsp. luisieri where only lipophilic secretions prevail.

A comparative study of the leaf microstructures of 19 taxa belonging to the Persicaria sect. Cephalophilon and related four Koenigia taxa was performed by LM and SEM to evaluate their systematic significance. Both amphistomatic and hypostomatic leaves were observed in the taxa studied. The stomatal size ranged from 17.04–41.96 × 13.41–37.30 μm, and stomata on the adaxial side were larger than those on the abaxial side in general. Anomocytic stomata occurred most commonly, but more than one type of stomata was observed on the same surface. Paracytic stomata was found in both Persicaria palmata and P. criopolitana. The epidermal cells usually have straight to sinuate anticlinal cell walls (ACW), and the ACW on the abaxial side of most taxa is much more undulated than that on the adaxial side. Cuticular striation was observed in most of the studied taxa, which was restricted to only the adaxial side. Two types of crystals were observed: druse and prismatic, and seven types of trichome were recognized: five types of non-glandular trichomes (stellate with smooth surface, multiseriate with either smooth or striated surface, and uniseriate with either smooth or papillose surface), and two types of glandular trichomes (peltate and long-stalked pilate). The leaf micromorphology in this study was categorized into five types based on the stomata, epidermis, crystal and trichome, as further systematic significance of the leaf epidermal characters within the P. sect. Cephalophilon are discussed. In addition, we propose a new taxonomic combination in the P. sect. Cephalophilon.

An attempt was made to understand the diversity of trichomes both at morphological and chemical levels in wild (Solanum viarum, S. mammosum, S. indicum, S. gilo, S. torvum) and cultivated eggplant (S. melongena) species. Cultivated and wild eggplant species have morphologically and chemically diverse trichomes. The presence of specific type of trichomes, their densities and chemical composition varied across species. The wild species viz., S. viarum and S. mammosum have seven (Type II to VIII) morphologically distinguishable types of trichomes including two types of glandular trichomes (Type VI, VII) as against uniform occurrence of branched stellate trichomes (Type VIII) alone in cultivated species. Differences among the phytochemicals viz., phenols and flavonoid levels were also observed across the eggplant species and type of trichomes.

Host plant resistance is an important component for minimizing the losses due to the pod borer, Helicoverpa armigera, which is the most devastating pest of pigeonpea. An understanding of different morphological and biochemical components of resistance is essential for developing strategies to breed for resistance to insect pests. Therefore, we studied the morphological and biochemical components associated with expression of resistance to H. armigera in wild relatives of pigeonpea to identify accessions with a diverse combination of characteristics associated with resistance to this pest. Among the wild relatives, oviposition non-preference was an important component of resistance in Cajanus scarabaeoides, while heavy egg-laying was recorded on C. cajanifolius (ICPW 28) and Rhynchosia bracteata (ICPW 214). Accessions belonging to R. aurea, C. scarabaeoides, C. sericeus, C. acutifolius, and Flemingia bracteata showed high levels of resistance to H. armigera, while C. cajanifolius was as susceptible as the susceptible check, ICPL 87. Glandular trichomes (type A) on the calyxes and pods were associated with susceptibility to H. armigera, while the non-glandular trichomes (trichome type C and D) were associated with resistance to this insect. Expression of resistance to H. armigera was also associated with low amounts of sugars and high amounts of tannins and polyphenols. Accessions of wild relatives of pigeonpea with non-glandular trichomes (type C and D) or low densities of glandular trichomes (type A), and high amounts of polyphenols and tannins may be used in wide hybridization to develop pigeonpea cultivars with resistance to H. armigera.

The poisonous and invasive weed Parthenium hysterophorus L., also referred to as "famine weed" or "congress grass," is highly dangerous for human health, agriculture, and biodiversity. This plant is well known for its aggressive growth and allelopathic qualities, which prevent natural vegetation and good crops from growing. An overview of the benefits and treatment of Parthenium hysterophorus is given in this abstract. Many techniques, including mechanical removal, chemical herbicides, biological control agents, and cultural practices, are used to combat this weed. To successfully control its spread, integrated techniques are frequently advised. Parthenium hysterophorus has drawbacks, yet it also has some positive qualities. It has therapeutic qualities, and research indicates that it may be used in phytoremediation and the synthesis of biofuel. The main goal is to draw attention to how critical it is to manage Parthenium hysterophorus properly while investigating its possible benefits, underscoring the necessity of long-term, all-encompassing solutions to deal with this environmental threat.

Ultrastructure and Secretion of Glandular Trichomes of Tobacco Leaves

The indumentum of Piriqueta and Turnera is made up of nine different types of trichomes, which broadly can be divided into glandular and non-glandular. Taking into account foot shape, head size and pedicle size, five variants of glandular trichomes are recognized: microcrapitate, stipitate-capitate, sessile-capitate and setiform. The non-glandular trichomes can be simple (unicellular or pluricellular-uniseriate), stellate or porrect-stellate. The setiform glandular hairs are present in most species of Piriqueta. Simple unicellular hairs are the most widespread type, frequently being found in combination with other trichomes. Stellate trichomes show a restricted distribution in both genera. Within Piriqueta, section Africana has only simple trichomes, whereas section Piriqueta has also porrect-stellate trichomes; groups of species can be set up according to the presence and type of glandular trichomes. Within Turnera the stipitate-capitate trichomes are exclusive to series Papilliferae; sessile-capitate trichomes are found in series Microphyllae, Annulares and in some species of Salicifoliae; clavate trichomes are found only in series Turnera; setiform glandular hairs are exclusive to T. collotricha, whereas the microcapitate trichomes are widely distributed.

The types, morphology, distribution, structure, and development process of the glandular trichomes on the leaves of Thymus quinquecostatus Celak had been investigated in this study. Two different types of glandular trichomes were determined in detail, namely, capitate trichomes and peltate ones. Besides, there were distinct differences on morphology, distribution, structure, and development process between the two kinds of trichomes. As the peltate trichome stepping into senium stage, it caved in the epidermis integrally, which was different from the capitate one. The secretion of the capitate trichome contained essential oil, polyphenols, and flavonoids, while, in addition to these three components, the secretion of the peltate one also contained acid polysaccharides. A distinctive difference was also seen in the secretory pathway of the secretion between the two types of trichomes. The secretion of capitate one was extruded through the cuticle of the head cell, but the secretion of the peltate one kept accumulating in the subcuticular space of the head cells until it was released by cuticle rupture.

Invasive alien plant species are recognized as a significant threat for species extinction globally. Sri Lanka, been a tropical country has the optimum conditions for distribution of various invasive plant species, and they are a threat to the local biodiversity. Many research have been carried out towards utilization of such plants as a method of successful eradication. Horticultural growers use synthetic fungicides to overcome the problems caused by plant pathogenic fungi, and it has lead to many negative impacts on environment and human health. Consequently, demand for the natural fungicides is increasing. With this background, there is a potential to use invasive plants as natural fungicides due to the presence of bioactive compounds within them. Tithonia diversifolia is an invasive plant species in Sri Lanka. The aim of this study was to find the efficacy of T. diversifolia leaf extracts to inhibit selected fungal pathogens causing leaf spots in ornamental plants. Extractions were done using methanol, dichloromethane and n-hexane. Antifungal activity was tested using standard methods against Curvularia sp., Fusarium sp., and Alternaria sp. Highest inhibition for Curvularia sp. and Fusarium sp. were obtained in n-hexane and methanolic leaf extracts respectively. Minimum inhibitory concentration (MIC) for the Curvularia sp. in n-hexane was 0.0175 g/ml and MIC for Fusarium sp. in methanolic extract was less than 0.0175 g/ml. Leaf anatomical observations revealed three types of trichomes. They were non-grandular and two types of glandular trichomes; capitate and non-capitate. Preliminary tests and Gas chromatographic analysis were done to determine the phytochemical constituents of the three extracts. Results revealed that the three extracts are different from each other where methanolic and dichloromethane were capable in extracting more secondary metabolic compounds. Methanolic and dichloromethane were tested for total phenolics and methanolic extract had the highest content with a 4.4963 μg/ml. Therefore, it can be concluded that leaf extracts from T. diversifolia have the potential to be used as a natural fungicide on disease causing fungi in plants while conserving biodiversity. Keywords: Invasive species, Tithonia diversifolia, Natural fungicides, Phytochemical, Biodiversity

In Parthenium hysterophorus L. four trichome types i.e. (1) cylindrical hair, (2) moniliform hair, (3) simple multiseriate hair and (4) shaggy hair, have been recognized mostly on the basis of their structural differences. In the past, these types have not been observed in any species of Parthenium studied so far. Out of these four, two types i.e. cylindrical and moniliform hairs are known to occur in the Compositae and remaining two i.e. simple multiseriate and shaggy hairs are the new forms for the family and have been observed for the first time in presently investigated species. Trichomes are an important taxonomic tool in distinguishing between genera and species. Trichomes of the different species of Parthenium as noticed from their structure are useful in distinguishing these species and even their corresponding organs.

Suppressive abilities of legume fodder plants against the invasive weed Parthenium hysterophorus (Asteraceae)

Light, conventional and environmental scanning electron microscopy of the trichomes of Cucurbita pepo subsp. pepo var. styriaca and histochemistry of glandular secretory products.

Stereological and histochemical analyses of the glandular trichomes on leaves of Rosmarinus officinalis were carried out using light and fluorescence microscopy. Non-glandular and two types of glandular trichomes – peltate and capitate – are described. The stereological method was used for estimating the volume density of epidermis, mesophyll, mechanical tissue, central cylinder, intercellular spaces and volume density of different types of glandular trichomes. The results showed that the volume density of adaxial epidermis was higher than abaxial epidermis. The volume density of peltate trichomes was higher than the volume density of capitate ones. The values obtained for number of peltate and capitate trichomes showed that the capitate trichomes type I were more numerous. The histochemical tests showed positive reactions to proteins and polysaccharides for both types of trichomes, while the phenolic substances were found only in peltate trichomes.