Genetic Basis of Carnivorous Leaf Development

Plant carnivory is often manifested as dramatic changes in the structure and morphology of the leaf. These changes appear to begin early in leaf development. For example, the development of the Sarracenia purpurea leaf primordium is associated with the formation of an adaxial ridge, whose growth along with that of the leaf margin resulted in a hollow structure that later developed into a pitcher. In Nepenthes khasiana, pitcher formation occurs during the initial stages of leaf development, although this has not been shown at the primordial stage. The formation of the Utricularia gibba trap resulted from the growth of the dome-shaped primordium in both the longitudinal and transverse directions. Recent research has begun to unfold the genetic basis of the development of the carnivorous leaf. We review these findings and discuss them in relation to the flat-shaped leaves of the model plant Arabidopsis.

Characterization of Carnivorous Plants Sarracenia Purpurea L. Transformed with Agrobacterium Rhizogenes

Carnivorous plant of Sarracenia genus are used by human in folk medicine for centuries. The reason for this phenomenon is biochemical composition of Sarracenia plants, which possess many bioactive compounds with anti-inflammatory, antioxidant, antiviral and antibacterial properties.The subject of this research was genetic transformation of Sarracenia purpurea L. with Agrobacterium rhizogenes strain 15834, 9402 and A4 by using two alternatively methods of bacterial injection or co-culture the bacteria with plants explants. These studies confirmed the possibility of hairy roots induction in S. purpurea using the strain of A. rhizogenes 15834 and the injection method. Seven lines of transformed plants, exhibiting the integration of rolB gene, were obtained. The formed hairy roots showed morphological differences in comparison to the roots of unmodified plants. A mathematical model was used to optimize the conditions for the extraction of bioactive compounds. Extracts isolated under optimal conditions from transformed plants showed biochemical changes i.e., the increase in the accumulation of total polyphenols and triterpenes in comparison to untransformed plants, especially when induced roots were analyzed. HPLC analysis showed increase in the level of betulinic acid in some transformed Sarracenia lines. Betulinic acid remains pentacyclic triterpenoid compound with high pharmacological significance. The further work connected with isolation and identification of the other bioactive compounds will be done in the nearest future.

Anti-herpes virus activity of the carnivorous botanical, Sarracenia purpurea

Herpes simplex virus type-1 (HSV-1), one of the most widely spread human viruses in the Herpesviridae family, causes herpes labialis (cold sores) and keratitis (inflammation of the cornea). Conventional treatment for HSV-1 infection includes pharmaceutical drugs, such as acyclovir and docosonal, which are efficacious but maintain the potential for the development of viral drug resistance. Extracts from the carnivorous pitcher plant, Sarracenia purpurea, have previously been shown to inhibit the replication of HSV-1. In this study, we demonstrate that S. purpurea extracts can inhibit the replication of HSV-1 by two distinct mechanisms of action. These extracts directly inhibit extracellular virions or viral attachment to the human host cell as well as inhibiting the expression of viral immediate-early, early and late genes when added at various times post-infection. This botanical has previously been shown to inhibit the replication of poxviruses through the inhibition of early viral gene transcription. These results support a broader anti-viral activity of S. purpurea extracts against both pox and herpes viruses.

Developmental sequence of the syncarpous gynoecium of Sarracenia purpurea (Sarraceniaceae) with flattened and broadened carpels and an umbrella-shaped style

The umbrella-shaped style of Sarracenia has a flattened and broadened distal half forming an umbrella canopy, and a slender cylindrical proximal half forming an umbrella stalk. The developmental sequence that gives rise to this unique structure has never been studied in detail. Data from light microscopy and scanning electron microscopy showed that the five carpels are initiated as discrete primordia, which then undergo congenital fusion and conduplicate folding and become a pentagonal syncarpous gynoecium. The distal region of the carpel then bends abaxially and undergoes significant expansion via a marginal meristem, forming the umbrella shape. Carpel closure is achieved via postgenital fusion at both transverse and longitudinal slits. Each of the five pollen tube transmitting tracts is enclosed by the adaxial surface of the carpel, and the inner epidermis of the umbrella canopy represents the expanded abaxial surface of the carpels, whereas the outer epidermis represents the expanded distal region of the fused carpellary margins. Epidermal trichomes develop first, then secretory glands and stomata appear later at the same stage on the umbrella canopy. This study provides insights into the evolution of the umbrella-shaped style utilizing both common and specialized carpel developmental programs with a novel spatial and temporal pattern.

Regulation by the Pitcher Plant Sarracenia purpurea of the Structure of its Inquiline Food Web

ABSTRACTPhytotelmata, the water-filled habitats in pitcher plants, bromeliad tanks, and tree-holes, host multitrophic food webs that are model experimental systems for studying food-web structure and dynamics. However, the plant usually is considered simply as an inert container, not as an interacting part of the food web. We used a response-surface and factorial field experiment to determine effects of nutrient enrichment (multiple levels of NH4NO3, PO4, and captured prey), top predator (removed or present), and the plant itself (with or without plastic tubes inserted into the pitchers to isolate the food web from the plant) on the macrobial food web within the modified leaves (“pitchers”) of the carnivorous pitcher plant Sarracenia purpurea. Connection to the plant, addition of NH4NO3 and removal of the top predator significantly increased the food web’s saturation, defined as its trophic depth and number of interactions. No effects on food-web saturation resulted from addition of PO4 or supplemental prey. Plants such as S. purpurea that create phytotelmata are more than inert containers and their inhabitants are more than commensal inquilines. Rather, both the plant and the inquilines are partners in a complex network of interactions.

Stigma, pollen tube transmitting tract, and epidermal micromorphology of the style of Sarracenia purpurea (Sarraceniaceae)

Entomophilous flowers of the genus Sarracenia have a unique umbrella-shaped style, which consists of a broadened and flattened umbrella canopy and a thin cylindrical umbrella stalk. Anatomical and micromorphological features of the style of Sarracenia purpurea L. were studied using light microscopy and scanning electron microscopy. This study found that the pollen tube transmitting tracts (PTTTs) start as a semi-solid canal filled with endotrophic conducting tissue, and run from the peripheral to the center of the canopy where the PTTT becomes a hollow canal supported by ectotrophic conducting tissue. The presence of stomata on the epidermis of the canopy and chloroplasts in its ground parenchyma indicate photosynthetic activities. Convex epidermal cells with intense cuticular striations on the canopy that are similar yet different from those on various regions of the sepals and petals indicate that it may provide contrasting visual cues for pollinators. Multicellular secretory glands and trichomes, which may provide olfactory cues and tactical cues respectively, are also found on the canopy. Thus, the stylar umbrella not only serves as a region for pollen grain capture, pollen germination, and pollen tube transmission but may also play an important role during pollinator–flower interactions.