Phylogeny and highland adaptation of Chinese species in Allium section Daghestanica (Amaryllidaceae) revealed by transcriptome sequencing.

Allium L. is one of the largest monocotyledonous genera with extensive distribution in the Northern Hemisphere. The fundamental phylogenies of Allium have been investigated using many morphological and molecular characters. However, the morphological characters may not agree with the molecular results in some Allium groups or sections (such as the Chinese Allium section Daghestanica), which may result in ambiguous species relationships and hinder further evolutionary and adaptive researches. Here, transcriptome sequences of the six Chinese endemics from Allium section Daghestanica were collected, with their single-copy genes (SCGs) were extracted. The interspecies relationships were analyzed using concatenation and coalescent methods. The branch-site model (BSM) was conducted to detect the positively selected genes (PSGs) in five highland species of this section. Based on 1644, 1281 and 1580 SCGs in flowers, leaves, and flowers-leaves combination respectively, a robust consistent and well-resolved phylogeny was generated from the concatenation method. Strong conflicts among individual gene trees were detected in the coalescent method, and morphological characters were incongruent with molecular relationships to some degree. Many PSGs were involved in responses of various stresses and stimuli (e.g. hypoxia, low temperature, aridity), DNA repair, metabolism, nutrient or energy intake, photosynthesis, and signal transduction. Our study revealed a clear interspecies relationship of Chinese endemics in Allium section Daghestanica and suggested that the discordance between morphological characters and molecular relationships might result from that the former are more susceptible to convergence compared with the latter. PSGs detected in our study may provide some insights into highland adaptation in Allium species.

Microscopic investigations and pharmacognostic techniques used for the standardization of herbal drug Nigella sativa L.

A comprehensive account on standardization of herbal drug Nigella sativa L. (Tukhm-e-Kalonji) by using microscopic as well as pharmacognostic parameters. In the field of herbal medicines, the main issues are quality, purity, and effectiveness, as in many cases herbal drugs are knowingly or unknowingly substituted or adulterated with similar species or varieties. In herbal market the seeds of N. sativa are commonly adultered with seeds of Allium cepa L. intentionally or accidentally due to their similar morphology. In the present study, the microscopic characterization of herbal drug was done by morphological, palynological, and anatomical features. A great diversity was found in anatomical features of two species, as irregular epidermal cells, actinocytic stomata, and nonglandular trichomes were found in N. sativa while in A. cepa epidermal cells were rectangular in shape, stomata type was paracytic, and trichomes were absent. Pharmacognostic characterization was made by fluorescence analysis and physiochemical parameters. Physicochemical parameters like moisture content, total ash, acid insoluble ash, water soluble ash, and water insoluble ash were also evaluated. The above parameters, being reported to the first time for the studied plant species, and are significant towards establishing the microscopic and pharmacognostic standards for future identification and authentication of genuine herbal drug. RESEARCH HIGHLIGHTS: Microscopic Investigations for the standardization of herbal drug Nigella sativa L. (Tukhm-e-Kalonji). Pharmacognostic techniques are potentially significant for the standardization of herbal drug Nigella sativa in comparison with its adulterant. Useful for preparation of standards for herbal pharmacopeia.

Evolution of leaf blade anatomy in Allium (Amaryllidaceae) subgenus Amerallium with a focus on the North American species.

PREMISE OF THE STUDY: Reconstructing ancestral states is a useful method to understand the pathway and patterns of character evolution and to test specific hypotheses within a phylogenetic context. Using a phylogenetic hypothesis of the subgenus Amerallium and related subgenera based on molecular data, we reconstructed the evolutionary history of leaf blade anatomical characters and identified those characters that are most congruent with phylogenetic relationships. Furthermore, we used these character histories to investigate the evolution of terete leaves and explore a possible correlation between environment and leaf anatomy in the North American species. METHODS: Sixty-seven North American and Old World species were sampled from all major infrageneric taxa and lineages for transectional leaf anatomy. To provide a phylogenetic framework for interpretation, representatives of Old World Amerallium and related subgenera were added to a published data matrix of North American taxa and ITS, ETS, trnL-F, and rpL32-trnL sequences. KEY RESULTS: Four anatomical characters, namely leaf-blade shape in transection, presence versus absence of palisade mesophyll, distribution and orientation of vascular bundles, and position of laticifer cells, were found to be congruent with phylogenetic relationships and useful diagnostic traits within North American species. Character reconstructions show that terete leaves in North American species evolved from flattened leaves via a possible transition from subterete to terete leaves. Furthermore, terete leaves possess traits that are indicative of possible adaptation to xeric environments. CONCLUSIONS: The findings from this study provide valuable information for understanding the evolution of leaf-blade anatomy in North American Allium species.

Nectar and flower traits of different onion male sterile lines related to pollination efficiency and seed yield of F1 hybrids.

Honey bees are the main pollinators of onion crops for seed production, but owing to low attractiveness of flowers, pollination is often inadequate. Pollination problems result in low seed yields. This problem is accentuated when male sterile lines (MSL) are used to produce hybrid onion seeds. In this study, the effect of floral attributes and nectar composition on the preference of honey bees of four MSLs and one onion open pollinated cultivar were assessed. The chemical composition of nectar was described through the analysis of sugars, trace elements, volatile organic compounds, and phenol compounds. The samples studied showed qualitative and quantitative differences in the analyzed traits of flowers and nectar among the different lines. Furthermore, field observations showed a great difference on the number of bee visits and seed yield among the onion lines analyzed. For the first time, this study demonstrates that there are marked differences in the chemical composition of nectar and floral morphology between open pollinated and MSLs and also within MSLs. In addition, these differences were correlated with the number of visits and seed yield. Therefore, it would be possible to select indirectly the most promising productive MSL using simple determinations of chemical compounds or floral morphological characters.

Phylogenetic analysis of Allium subg. Melanocrommyum infers cryptic species and demands a new sectional classification.

Allium subgenus Melanocrommyum (Alliaceae) from Eurasia comprises about 150 mostly diploid species adapted to arid conditions. The group is taxonomically complicated with different and contradictory taxonomic treatments, and was thought to include a considerable number of hybrid species, as the taxa show an admixture of assumed morphological key characters. We studied the phylogeny of the subgenus, covering all existing taxonomic groups and their entire geographic distribution. We analyzed sequences of the nuclear rDNA internal transcribed spacer region (ITS) for multiple individuals of more than 100 species. Phylogenetic analyses of cloned and directly sequenced PCR products confirmed the monophyly of the subgenus, while most sections were either para- or polyphyletic. The splits of the large sections are supported by differences in the anatomy of flower nectaries. ITS data (i) demand a new treatment at sectional level, (ii) do not support the hypotheses of frequent gene flow among species, (iii) indicate that multiple rapid radiations occurred within different monophyletic groups of the subgenus, and (iv) detected separately evolving lineages within three morphologically clearly defined species (cryptic species). In two cases these lineages were close relatives, while in Allium darwasicum they fall in quite different clades in the phylogenetic tree. Fingerprint markers show that this result is not due to ongoing introgression of rDNA (ITS capture) but that genome-wide differences between both lineages exist. Thus, we report one of the rare cases in plants where morphologically indistinguishable diploid species occurring in mixed populations are non-sister cryptic species.

Structural aspects and ecophysiology of anther opening in Allium triquetrum.

BACKGROUND AND AIMS: Tissue desiccation is considered to be involved in anther opening, and it is agreed that environmental humidity affects its timing. Different sources of evidence suggest that the later steps of the process (i.e. stomium opening and outward wall bending) are regulated in different ways. Anther opening was studied in Allium triquetrum under four regimes of relative humidity (RH) to analyse the effect of this parameter and to speculate about its possible regulation. METHODS: Anther histology was studied in cross-sections under a microscope. The times of visible anther opening and complete outward wall bending were recorded separately for each level of RH. Frequency distributions were plotted to express anther behaviour. KEY RESULTS: When a longitudinal stomium breaks the anther remains closed due to adherence of walls on each side of the stomium. Anther opening occurs when the adhering walls subsequently separate. Later, the walls shrink laterally and bend outward. The anthers of the inner whorl opened during the morning of the first day of anthesis, while those of the outer whorl opened during the afternoon. Low RH (20 %) did not cause any evident acceleration of anther opening, but it did cause delay and inhibition of the opening of some anthers in the outer whorl. High RH (55 and 98 %) caused different degrees of delay and also inhibition of anther opening, but most anthers opened within the expected range of time. The time taken for outward wall bending was shortened at 20 % RH. Anther wall outward bending was inhibited at 55 % and 98 % RH. CONCLUSIONS: Anther opening occurred at a specific moment of anther development, separated in time from stomium breakage, and seemed related to dehydration caused by reabsorption of water by contiguous tissues. Outward bending of the wall was facilitated by evaporation. Anther opening and anther wall outward bending seemed to be regulated differently in relation to water control.

Evolution of genome size across some cultivated Allium species.

Allium L. (Alliaceae), a genus of major economic importance, exhibits a great diversity in various morphological characters and particularly in life form, with bulbs and rhizomes. Allium species show variation in several cytogenetic characters such as basic chromosome number, ploidy level, and genome size. The purpose of the present investigation was to study the evolution of nuclear DNA amount, GC content, and life form. A phylogenetic approach was used on a sample of 30 Allium species, including major vegetable crops and their wild allies, belonging to the 3 major subgenera Allium, Amerallium, and Rhizirideum and 14 sections. A phylogeny was constructed using internal transcribed spacer (ITS) sequences of 43 accessions representing 30 species, and the nuclear DNA amount and the GC content of 24 Allium species were investigated by flow cytometry. For the first time, the nuclear DNA content of Allium cyaneum and Allium vavilovii was measured, and the GC content of 16 species was measured. We addressed the following questions: (i) Is the variation in nuclear DNA amount and GC content linked to the evolutionary history of these edible Allium species and their wild relatives? (ii) How did life form (rhizome or bulb) evolve in edible Allium? Our results revealed significant interspecific variation in the nuclear DNA amount as well as in the GC content. No correlation was found between the GC content and the nuclear DNA amount. The reconstruction of nuclear DNA amount on the phylogeny showed a tendency towards a decrease in genome size within the genus. The reconstruction of life form history showed that rhizomes evolved in the subgenus Rhizirideum from an ancestral bulbous life form and were subsequently lost at least twice independently in this subgenus.

Frequencies of plasmodesmata in Allium cepa L. roots: implications for solute transport pathways.

Plasmodesmatal frequencies (PFs) were analysed in Allium cepa L. roots with a mature exodermis (100 mm from the tip). For all interfaces within the root, the numbers of plasmodesmata (PD) microm(-2) wall surface (Fw) were calculated from measurements of 60 walls on ultrathin sections. For tissues ranging from the epidermis up to the stelar parenchyma, the frequencies were also expressed as total PD numbers mm(-1) root length (Fn), which is most instructive for considering the radial transport of ions and photosynthates (because the tissues were arranged in concentric cylinders). The Fn values were constantly high at the interfaces of exodermis-central cortex, central cortex-endodermis and endodermis-pericycle (4.05x10(5), 5.13x10(5), and 5.64x10(5), respectively). If the plasmodesmata are functional, a considerable symplastic transport pathway exists between the exodermis and pericycle. Two interfaces had especially low PFs: epidermis-exodermis (Fn=8.96x10(4)) and pericycle-stelar parenchyma (Fn=6.44x10(4)). This suggests that there is significant membrane transport across the interface of epidermis-exodermis (through short cells) and direct transfer of ions from pericycle to protoxylem vessels. In the phloem, the highest PF was detected at the metaphloem sieve element-companion cell interface (Fw=0.42), and all other interfaces had much lower PFs (around 0.10). In the pericycle, the radial walls had a high PF (Fw=0.75), a feature that could permit lateral circulation of solutes, thus facilitating ion (inward) and photosynthate (outward) delivery.