Micropropagation of Rare Scutellaria havanensis Jacq. and Preliminary Studies on Antioxidant Capacity and Anti-Cancer Potential.

We report the development of in vitro propagation protocols through an adventitious shoot induction pathway for a rare and medicinal Scutellaria havanensis. In vitro propagation studies using nodal explants showed MS medium supplemented with 10 µM 6-Benzylaminopurine induced the highest number of adventitious shoots in a time-dependent manner. A ten-day incubation was optimum for shoot bud induction as longer exposures resulted in hyperhydricity of the explants and shoots induced. We also report preliminary evidence of Agrobacterium tumefaciens EHA105-mediated gene transfer transiently expressing the green fluorescent protein in this species. Transformation studies exhibited amenability of various explant tissues, internode being the most receptive. As the plant has medicinal value, research was carried out to evaluate its potential antioxidant capacity and the efficacy of methanolic leaf extracts in curbing the viability of human colorectal cancer cell line HCT116. Comparative total polyphenol and flavonoid content measurement of fresh and air-dried leaf extract revealed that the fresh leaf extracts contain higher total polyphenol and flavonoid content. The HCT 116 cell viability was assessed by colorimetric assay using a 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide, showed a steady growth inhibition after 24 h of incubation. Scanning electron microscopy of leaf surface revealed a high density of glandular and non-glandular trichomes. This research provides a basis for the conservation of this rare plant and future phytochemical screening and clinical research.

Genome structure and metabolic features in the red seaweed Chondrus crispus shed light on evolution of the Archaeplastida.

Red seaweeds are key components of coastal ecosystems and are economically important as food and as a source of gelling agents, but their genes and genomes have received little attention. Here we report the sequencing of the 105-Mbp genome of the florideophyte Chondrus crispus (Irish moss) and the annotation of the 9,606 genes. The genome features an unusual structure characterized by gene-dense regions surrounded by repeat-rich regions dominated by transposable elements. Despite its fairly large size, this genome shows features typical of compact genomes, e.g., on average only 0.3 introns per gene, short introns, low median distance between genes, small gene families, and no indication of large-scale genome duplication. The genome also gives insights into the metabolism of marine red algae and adaptations to the marine environment, including genes related to halogen metabolism, oxylipins, and multicellularity (microRNA processing and transcription factors). Particularly interesting are features related to carbohydrate metabolism, which include a minimalistic gene set for starch biosynthesis, the presence of cellulose synthases acquired before the primary endosymbiosis showing the polyphyly of cellulose synthesis in Archaeplastida, and cellulases absent in terrestrial plants as well as the occurrence of a mannosylglycerate synthase potentially originating from a marine bacterium. To explain the observations on genome structure and gene content, we propose an evolutionary scenario involving an ancestral red alga that was driven by early ecological forces to lose genes, introns, and intergenetic DNA; this loss was followed by an expansion of genome size as a consequence of activity of transposable elements.

OUROBOROS is a master regulator of the gametophyte to sporophyte life cycle transition in the brown alga Ectocarpus.

The brown alga Ectocarpus siliculosus has a haploid-diploid life cycle that involves an alternation between two distinct generations, the sporophyte and the gametophyte. We describe a mutant, ouroboros (oro), in which the sporophyte generation is converted into a functional, gamete-producing gametophyte. The life history of the mutant thus consists of a continuous reiteration of the gametophyte generation. The oro mutant exhibited morphological features typical of the gametophyte generation and accumulated transcripts of gametophyte generation marker genes. Genetic analysis showed that oro behaved as a single, recessive, Mendelian locus that was unlinked to the IMMEDIATE UPRIGHT locus, which has been shown to be necessary for full expression of the sporophyte developmental program. The data presented here indicate that ORO is a master regulator of the gametophyte-to-sporophyte life cycle transition and, moreover, that oro represents a unique class of homeotic mutation that results in switching between two developmental programs that operate at the level of the whole organism.

Non-cell autonomous regulation of life cycle transitions in the model brown alga Ectocarpus.

The model brown alga Ectocarpus has a haploid-diploid life cycle, involving alternation between two independent multicellular generations, the gametophyte and the sporophyte. Recent work has shown that alternation of generations is not determined by ploidy but is rather under genetic control, involving at least one master regulatory locus, OUROBOROS (ORO). Using cell biology approaches combined with measurements of generation-specific transcript abundance we provide evidence that alternation of generations can also be regulated by non-cell autonomous mechanisms. The Ectocarpus sporophyte produces a diffusible factor that causes major developmental reprogramming in gametophyte cells. Cells become resistant to reprogramming when the cell wall is synthetized, suggesting that the cell wall may play a role in locking an individual into the developmental program that has been engaged. A functional ORO gene is necessary for the induction of the developmental switch. Our results highlight the role of the cell wall in maintaining the differentiated generation stage once the appropriate developmental program has been engaged and also indicate that ORO is a key member of the developmental pathway triggered by the sporophyte factor. Alternation between gametophyte and sporophyte generations in Ectocarpus is surprisingly labile, perhaps reflecting an adaptation to the variable seashore environment inhabited by this alga.

Biochemical and Molecular Characterization of Musa sp. Cultured in Temporary Immersion Bioreactor.

The genus Musa sp. contains commercially important fleshy fruit-producing plants, including plantains and bananas, with a strong potential for providing food security and sources of revenue to farmers. Concerns with the quality of vegetative tissues along with the possibility of the transmission of phytopathogens makes the availability of healthy plantlets limited for farmers. Micropropagation of plantains offers an alternative to producing large numbers of plantlets. However, conventional methods of micropropagation have high production costs and are labor-intensive. Recently, the temporary immersion bioreactor (TIB) has emerged as an alternative to conventional micropropagation (CM) methods. Our work utilized SEM microscopy (scanning electron microscope) and molecular and biochemical tools (qRT-PCR and ICP-OES) to characterize and compare the morphological properties, elemental composition, and photosynthetic gene expression of plantains cultured on TIB. Additionally, morphological features of growth and propagation rates were analyzed to compare outputs obtained from TIB and CM. Results showed higher growth and multiplication rates for plantlets cultivated in TIB. Gene expression analysis of selected photosynthetic genes demonstrated high transcript abundance of phosphoenolpyruvate carboxylase (PEPC) in plantain tissues obtained by TIB. Elemental composition analysis showed higher content of iron in plantains grown in TIB, suggesting a potential correlation with PEPC expression. These results demonstrate that micropropagation of Musa sp. via the liquid medium in TIB is an efficient and low-cost approach in comparison with solid media in CM.

Mosaic Evolution of Molecular Pathways for Sex Pheromone Communication in a Butterfly.

Unraveling the origin of molecular pathways underlying the evolution of adaptive traits is essential for understanding how new lineages emerge, including the relative contribution of conserved ancestral traits and newly evolved derived traits. Here, we investigated the evolutionary divergence of sex pheromone communication from moths (mostly nocturnal) to butterflies (mostly diurnal) that occurred ~119 million years ago. In moths, it is the females that typically emit pheromones to attract male mates, but in butterflies males emit pheromones that are used by females for mate choice. The molecular bases of sex pheromone communication are well understood in moths, but they have remained relatively unexplored in butterflies. We used a combination of transcriptomics, real time qPCR, and phylogenetics to identify genes involved in the different steps (i.e., production, regulation, and reception) of sex pheromone communication of the butterfly Bicyclus anynana. Our results show that the biosynthesis and reception of sex pheromones relies both on moth-specific gene families (reductases) and on more ancestral insect gene families (desaturases, olfactory receptors, odorant binding proteins). Interestingly, B. anynana appears to use what was believed to be the moth-specific neuropeptide Pheromone Biosynthesis Activating Neuropeptide (PBAN) for regulating sex pheromone production. Altogether, our results suggest that a mosaic pattern best explains how sex pheromone communication evolved in butterflies, with some molecular components derived from moths, and others conserved from more ancient insect ancestors. This is the first large-scale investigation of the genetic pathways underlying sex pheromone communication in a butterfly.

Convergent recruitment of TALE homeodomain life cycle regulators to direct sporophyte development in land plants and brown algae.

Three amino acid loop extension homeodomain transcription factors (TALE HD TFs) act as life cycle regulators in green algae and land plants. In mosses these regulators are required for the deployment of the sporophyte developmental program. We demonstrate that mutations in either of two TALE HD TF genes, OUROBOROS or SAMSARA, in the brown alga Ectocarpus result in conversion of the sporophyte generation into a gametophyte. The OUROBOROS and SAMSARA proteins heterodimerise in a similar manner to TALE HD TF life cycle regulators in the green lineage. These observations demonstrate that TALE-HD-TF-based life cycle regulation systems have an extremely ancient origin, and that these systems have been independently recruited to regulate sporophyte developmental programs in at least two different complex multicellular eukaryotic supergroups, Archaeplastida and Chromalveolata.

Sequencing and De Novo Assembly of the Complete Chloroplast Genome of the Peruvian Carrot (Arracacia xanthorrhiza Bancroft).

Arracacia xanthorrhiza is an important secondary food crop in South America and Puerto Rico. The lack of crop protection and improvement strategies leads to infections damaging the storage roots. Here, we report the annotated complete chloroplast genome sequence of A. xanthorrhiza as a step toward developing genomic resources for this crop.

Selection and validation of reference genes for qRT-PCR expression analysis of candidate genes involved in olfactory communication in the butterfly Bicyclus anynana.

Real-time quantitative reverse transcription PCR (qRT-PCR) is a technique widely used to quantify the transcriptional expression level of candidate genes. qRT-PCR requires the selection of one or several suitable reference genes, whose expression profiles remain stable across conditions, to normalize the qRT-PCR expression profiles of candidate genes. Although several butterfly species (Lepidoptera) have become important models in molecular evolutionary ecology, so far no study aimed at identifying reference genes for accurate data normalization for any butterfly is available. The African bush brown butterfly Bicyclus anynana has drawn considerable attention owing to its suitability as a model for evolutionary ecology, and we here provide a maiden extensive study to identify suitable reference gene in this species. We monitored the expression profile of twelve reference genes: eEF-1α, FK506, UBQL40, RpS8, RpS18, HSP, GAPDH, VATPase, ACT3, TBP, eIF2 and G6PD. We tested the stability of their expression profiles in three different tissues (wings, brains, antennae), two developmental stages (pupal and adult) and two sexes (male and female), all of which were subjected to two food treatments (food stress and control feeding ad libitum). The expression stability and ranking of twelve reference genes was assessed using two algorithm-based methods, NormFinder and geNorm. Both methods identified RpS8 as the best suitable reference gene for expression data normalization. We also showed that the use of two reference genes is sufficient to effectively normalize the qRT-PCR data under varying tissues and experimental conditions that we used in B. anynana. Finally, we tested the effect of choosing reference genes with different stability on the normalization of the transcript abundance of a candidate gene involved in olfactory communication in B. anynana, the Fatty Acyl Reductase 2, and we confirmed that using an unstable reference gene can drastically alter the expression profile of the target candidate genes.

Brown algae as a model for plant organogenesis.

Brown algae are an extremely interesting, but surprisingly poorly explored, group of organisms. They are one of only five eukaryotic lineages to have independently evolved complex multicellularity, which they express through a wide variety of morphologies ranging from uniseriate branched filaments to complex parenchymatous thalli with multiple cell types. Despite their very distinct evolutionary history, brown algae and land plants share a striking amount of developmental features. This has led to an interest in several aspects of brown algal development, including embryogenesis, polarity, cell cycle, asymmetric cell division and a putative role for plant hormone signalling. This review describes how investigations using brown algal models have helped to increase our understanding of the processes controlling early embryo development, in particular polarization, axis formation and asymmetric cell division. Additionally, the diversity of life cycles in the brown lineage and the emergence of Ectocarpus as a powerful model organism, are affording interesting insights on the molecular mechanisms underlying haploid-diploid life cycles. The use of these and other emerging brown algal models will undoubtedly add to our knowledge on the mechanisms that regulate development in multicellular photosynthetic organisms.

Genetic regulation of life cycle transitions in the brown alga Ectocarpus.

The life cycle of an organism is one of its most elemental features, underpinning a broad range of phenomena including developmental processes, reproductive fitness, mode of dispersal and adaptation to the local environment. Life cycle modification may have played an important role during the evolution of several eukaryotic groups, including the terrestrial plants. Brown algae are potentially interesting models to study life cycle evolution because this group exhibits a broad range of different life cycles. Currently, life cycle studies are focused on the emerging brown algal model Ectocarpus. Two life cycle mutants have been described in this species, both of which cause the sporophyte generation to exhibit gametophyte characteristics. The ouroboros mutation is particularly interesting because it induces complete conversion of the sporophyte generation into a functional, gamete-producing gametophyte, a class of mutation that has not been described so far in other systems. Analysis of Ectocarpus life cycle mutants is providing insights into several life-cycle-related processes including parthenogenesis, symmetric/asymmetric initial cell divisions and sex determination.