Assembly of a simple scalable device for micromechanical testing of plant tissues.

Tensile testing is widely used to evaluate the mechanical properties of biological materials including soft primary plant tissues. Commercially available platforms for tensile testing are often expensive and limited in customizability. In this chapter, we provide a guide for the assembly and use of a simple and low-cost micromechanical testing apparatus suitable for research and educational purposes. The build of the setup is presented with scalability and universality in mind and is based on a do-it-yourself mind frame towards mechanical tests on plant organs and tissues. We discuss hardware and software requirements with practical details on required components, device calibration and a script to run the device. Further, we provide an example in which the device was used for the uniaxial tensile test of onion epidermis.

An improved centrifuge method for determining water extraction curves and vulnerability curves in the long-vessel species Robinia pseudoacacia.

Significant improvements to the centrifuge water-extraction method of measuring the percentage loss volume of water (PLV) and corresponding vulnerability curves (VCs) are reported. Cochard and Sperry rotors are both incapable of measuring the VCs of species with long vessels because of premature embolism induced by hypothetical nanoparticles that can be drawn into segments during flow measurement. In contrast, water extraction pushes nanoparticles out of the sample. This study focuses on a long-vessel species, Robinia pseudoacacia, for which many VCs have been constructed by different methods, and the daily water relations have been quantified. PLV extraction curves have dual Weibull curves, and this paper focuses on the second Weibull curve because it involves the extraction of water from vessels, as proven by staining methods. We demonstrate an improved water extraction method after evaporation correction that has accuracy to within 0.5%, shows good agreement with two traditional methods that are slower and less accurate, and is immune to nanoparticle artefacts. Using Poiseuille's Law and the geometry of vessels, we argue that the percentage loss of conductivity (PLC) equals 2PLV-PLV2 in a special case where all vessels, regardless of size, have the same vulnerability curve. In this special case, this equation predicts the data reasonably well.

Depolarizing metrics for plant samples imaging.

Optical methods, as fluorescence microscopy or hyperspectral imaging, are commonly used for plants visualization and characterization. Another powerful collection of optical techniques is the so-called polarimetry, widely used to enhance image contrast in multiple applications. In the botanical applications framework, in spite of some works have already highlighted the depolarizing print that plant structures left on input polarized beams, the potential of polarimetric methods has not been properly exploited. In fact, among the few works dealing with polarization and plants, most of them study light scattered by plants using the Degree of Polarization (DoP) indicator. Other more powerful depolarization metrics are nowadays neglected. In this context, we highlight the potential of different depolarization metrics obtained using the Mueller matrix (MM) measurement: the Depolarization Index and the Indices of Polarimetric Purity. We perform a qualitative and quantitative comparison between DoP- and MM-based images by studying a particular plant, the Hedera maroccana. We show how Mueller-based metrics are generally more suitable in terms of contrast than DoP-based measurements. The potential of polarimetric measurements in the study of plants is highlighted in this work, suggesting they can be applied to the characterization of plants, plant taxonomy, water stress in plants, and other botanical studies.

Sobre a botânica, a etnofarmacologia e a química de Calycophyllum spruceanum (Benth. ) Hook. f. ex K. Schum / On the botany, ethnopharmacology, and chemistry of Calycophyllum spruceanum (Benth. ) Hook. f. ex K. Schum

RESUMO O fato de possuir espécies com potencial econômico ilimitado, faz com que o ambiente amazônico se torne alvo constante da biopirataria e da extração predatória dos recursos. Muitas espécies deste ambiente sequer possuem catalogação e, mesmo assim, encontram risco eminente de desaparecimento. Neste âmbito, trabalhos que reúnam dados sobre estas espécies possuem grande valor científico, cultural e econômico, sendo este o estímulo que desencadeou a produção desta revisão. Aqui a espécie Calycophyllum spruceanum (Benth.) Hook. f. ex K. Schum., uma Rubiaceae amazônica, é contemplada por meio de características botânicas, indicações etnofarmacológicas e propriedades químicas. Popularmente conhecida como mulateiro, a espécie é frequentemente receitada na etnomedicina como cicatrizante e rejuvenescedor, além de ser usada no controle de manchas de pele. Como peculiaridade botânica, mulateiro apresenta tronco retilíneo com epiderme fina esverdeada que evolui para uma periderme castanho-escuro, que é anualmente renovada. Em termos químicos, há destaque para a presença de alcalóides, taninos e, sobretudo, secoiridóides (7-metoxididerrosideo, 6´-acetil-β-D-glucopiranosildiderrosideo e 8-0-tigloildiderrosideo são peculiares à espécie). Mesmo com propriedades fotoprotetoras comprovadas, C. spruceanum ainda carece de pesquisas, sobretudo àquelas voltadas para a produção ex situ da planta e àquelas que demonstrem a relação entre a ecologia da planta e a produção de metabólitos funcionais para a indústria.

ABSTRACT The Amazonian environment is a constant target for biopiracy and predatory extraction of resources due to the species with vast economic potential. Many of these species have not even been cataloged, and yet are already at imminent risk of extinction. In this paper, Calycophyllum spruceanum (Benth.) Hook. f. ex k. Schum., an Amazonian Rubiaceae, is studied with information on its botanical characteristics, ethnopharmacological uses, and chemical properties. Popularly known as mulateiro, the species is often prescribed in ethnomedicine for healing and vitality, and is also used to control skin patches. As a botanical peculiarity, it has a thin green epidermis that evolves into a dark brown periderm, which is renewed annually. In terms of chemistry, there is emphasis on the presence of alkaloids, tannins, and, especially, secoiridoids (7-methoxydiderroside, 6′-acetyl-β-D-glucopyranosyldiderroside, and 8-O-tigloyldiderroside are peculiar to the species). Even with proven photoprotective properties, research on C. spruceanum is still lacking, in particular studies aimed at the ex situ production of the plant and those that show the relationship between the plant’s ecology and the production of functional metabolites for the industry.

An efficient petiole-feeding bioassay for introducing aqueous solutions into dicotyledonous plants.

Introducing bioactive molecules into plants helps establish their roles in plant growth and development. Here we describe a simple and effective petiole-feeding protocol to introduce aqueous solutions into the vascular stream and apoplast of dicotyledonous plants. This 'intravenous feeding' procedure has wide applicability to plant physiology, specifically with regard to the analysis of source-sink allocations, long-distance signaling, hormone biology and overall plant development. In comparison with existing methods, this technique allows the continuous feeding of aqueous solutions into plants without the need for constant monitoring. Findings are provided from experiments using soybean plants fed with a range of aqueous solutions containing tracer dyes, small metabolites, radiolabeled chemicals and biologically active plant extracts controlling nodulation. Typically, feeding experiments consist of (i) generating samples to feed (extracts, solutions and so on); (ii) growing recipient plants; (iii) setting up the feeding apparatus; and (iv) feeding sample solutions into the recipient plants. When the plants are ready, the feeding procedure can take 1-3 h to set up depending on the size of experiment (not including preparation of materials). The petiole-feeding technique also works with other plant species, including tomato, chili pepper and cabbage plants, as demonstrated here.