Identification of chemotaxonomic plant markers from the genus Centaurea L.

The use of chemotaxonomic methods for studying plants allows you to help identify the ancestral and species affiliation of closely related plants. Chemotaxonomy is especially useful for systematically young groups of plant taxa, characterized by great variability in morphological features, difficulty in identifying and clarifying systematic affiliation. The article analyses the content of various groups of biologically active compounds in plants of the genus Centaurea L. to find the most convenient chemotaxonomic markers. As a result of the analysis of the variability of flavonoids, sesquiterpene lactones, polysaccharides and other biologically active substances of the genus Centaurea, it was found that «flavonoid profiles» are most species-specific, and sesquiterpene lactones can serve as an additional taxonomic feature at the level of subgenera and sections of this genus. More detailed studies are needed to map the distribution of biologically active compounds as chemotaxonomic markers.

Completed Genomic Sequence of Bacillus thuringiensis HER1410 Reveals a Cry-Containing Chromosome, Two Megaplasmids, and an Integrative Plasmidial Prophage

Bacillus thuringiensis is the most used biopesticide in agriculture. Its entomopathogenic capacity stems from the possession of plasmid-borne insecticidal crystal genes (cry), traditionally used as discriminant taxonomic feature for that species. As such, crystal and plasmid identification are key to the characterization of this species. To date, about 600 B. thuringiensis genomes have been reported, but less than 5% have been completed, while the other draft genomes are incomplete, hindering full plasmid delineation. Here we present the complete genome of Bacillus thuringiensis HER1410, a strain closely related to B. thuringiensis entomocidus and a known host for a variety of Bacillus phages. The combination of short and long-read techniques allowed fully resolving the genome and delineation of three plasmids. This enabled the accurate detection of an unusual location of a unique cry gene, cry1Ba4, located in a genomic island near the chromosome replication origin. Two megaplasmids, pLUSID1 and pLUSID2 could be delineated: pLUSID1 (368 kb), a likely conjugative plasmid involved in virulence, and pLUSID2 (156 kb) potentially related to the sporulation process. A smaller plasmidial prophage pLUSID3, with a dual lifestyle whose integration within the chromosome causes the disruption of a flagellar key component. Finally, phylogenetic analysis placed this strain within a clade comprising members from the B. thuringiensis serovar thuringiensis and other serovars and with B. cereus s. s. in agreement with the intermingled taxonomy of B. cereus sensu lato group.

New And Neglected Morphological Features in the Taxonomy of Asian Lejeunea (Marchantiophyta)

The infrageneric classification of the large genus Lejeunea Lib. is poorly understood due to the lack of stable morphological characters characterizing supraspecific groups. Phenetic analysis of 26 morphological features of 31 Asian Lejeunea species separated two main species clusters based on the number of superior central cells at underleaf bases. The number of superior central cells had not previously been utilized in the classification of Lejeunea and appears to be new and stable morphological feature within this genus. The presence of surface wax was confirmed in L. flava (Sw.) Nees and was newly recorded in L. mimula Hürl. and L. tuberculosa Steph. We suggest that wax ornamentation may be a useful taxonomic feature at species level in Lejeunea.

A taxonomic revision of the genus Haplosyllis Langerhans, 1887 (Polychaeta: Syllidae: Syllinae)

The genus Haplosyllis Langerhans, 1887 is revised based on available types and newly collected specimens. 19 species are considered as valid, five as incertae sedis and four are referred to nomina dubia. Trypanoseta (Imajima, 1966) is synonymised with Haplosyllis, as the presence of trepan is considered a non-robust taxonomic feature, affecting H. ohma new comb. (Imajima & Hartman, 1964) and H. granulosa new comb. (Lattig, San Martín & Martín, 2007). Haplosyllis streptocephala (Grube, 1857) is a new combination and two species are considered to belong to Alcyonosyllis Glasby & Watson, 2001: A. bisetosa new comb. (Hartmann-Schröder, 1960) and A. gorgoniacola new comb. (Sun & Yang, 2004). All valid species are described and figured except those described during the last decade, which only includes diagnoses and chaetae illustrations. A dichotomous key to all valid species of Haplosyllis is provided.

Calcium Oxalate Cuticular Crystals in the Epidermis of Dracaena—A Taxonomic Feature of the Genus

The genus Dracaena has been placed in Agavaceae by most taxonomists. Recent work, however, has justified the placement in a separate family, Dracaenaceae. This study was initiated to examine the extracellular crystalline deposits in Dracaena and the possibility of this feature as a taxonomic trait of the genus. Fresh epidermal peels of five Dracaena species were observed under polarized light. Extracellular epidermal crystals were evident in all of them. The deposits were found between the cuticle and the outer primary epidermal cell wall. The crystal size varied from less than 1 μm to 5 μm along the long crystal axis. The size and quantity of the deposits varied between the species with largest and most numerous crystals in the cuticle of D. marginata and D. sanderiana. Dracaena deremensis, D. fragrans, and D. surculosa had smaller and less numerous crystals. The optical properties of the crystals were indicative of calcium oxalate monohydrate form which exhibited interference colors of second and third order. For comparison species of three members of Agavaceae were examined -Cordyline terminalis, Sansevieria trifasciata, and Yucca sp. No extracellular crystal deposits in the proximity of the epidermal wall were detected. Based on our observations, the genus Dracaena possessed an anatomical feature which could be used for identification. The existence of calcium oxalate crystals embedded in the cuticle was readily observable in fresh epidermal peels under polarized light.