Bioakumulasi Merkuri (Hg) pada Lamun Enhalus acoroides dan Mangrove Rhizophora apiculata di Pulau Pari, Kepulauan Seribu

<strong>Bioaccumulation of Mercury (Hg) in Seagrass <em>Enhalus acoroides</em> and Mangrove <em>Rhizophora apiculata</em> in Pari Island, Seribu Islands. </strong>Heavy metal pollution, especially Hg metal in Jakarta Bay, is feared to have a negative impact on the quality of the waters around the Jakarta Bay waters, one of which is Pari Island in the Thousand Islands. Seagrass and mangroves plants distributed surrounding Pari Island can be used as indicators of heavy metal pollution. The value of bioaccumulation and translocation of Hg metal factors will provide an overview of the ability of plants to accumulate heavy metals in their surroundings. This study aims to determine the bioaccumulation and translocation of the heavy metal Hg factor in <em>Enhalus acoroides</em> seagrass and <em>Rhizophora apiculata</em> mangroves on Pari Island, Seribu Islands. Seagrass and mangrove samples were taken at five sampling points through purposive sampling. The bioaccumulation value was calculated using the ratio of the metal concentrations in each part of the plant body and sediment. Meanwhile, the translocation factor value was calculated by the ratio of Hg concentration in each part of the plant body (roots/rhizomes, stems, and leaves). The results of this study indicate that the bioaccumulation value in seagrass is infinite (bioaccumulation factor, BAF=∞) and in mangroves is 1.57 (BAF&gt;1). The highest <em>translocation factor</em> value in seagrass leaves is 3.86 (translocation factor, TF) &gt;1) and in mangrove leaves is 2.84 (TF&gt;1). This study shows that seagrass and mangrove plants are classified as good bio accumulator and hyperaccumulator plants and accumulate heavy metals, especially Hg in the upper part of their bodies, namely leaves

Change of Several Plant Nutrient Elements by Plant Species and Organ

Nutrient elements, one of the major factors shaping plant development, are the major components of plants, and, after being taken from the soil, they are present in different organs of plant at different concentrations. The speciation of nutrient elements within plant body is vital importance for determining the contribution to plant development, knowing the transfer between organs within the body of organs, clearly understanding the factors influencing plant development, and shaping the plant development. In the present study, the change of the concentrations of K and Mg (macronutrient elements) and Cu (micronutrient elements) by species and organ in woody species Prunus cerasifera, Platanus orientalis, Acer negundo, Fraxinus excelsior, Catalpa bignonioides, Aesculus hippocastanum, and Tilia platypyllos. As a result, it was found that the changes of elements by species were statistically significant in all the organs, and, in general, the highest concentrations were observed in leaves. The study results revealed that the concentrations of these elements might significantly vary between the organs in the same species, which varies significantly by the species.

Penggunaan Student Teams Achievment Division (STAD) pada Materi Tubuh Tumbuhan dan Fungsinya untuk Meningkatkan Hasil Belajar Siswa Kelas III SDN Tamban Bangun Baru 1 oleh Fitriani

This study aims to determine, first whether the application of the STAD method can increase teacher activity in science learning material on plant body parts and functions in class III of SDN Tamban Bangun Baru 1? Second, can the application of the STAD method increase the activity of third graders at SDN Tamban Bangun Baru 1 in learning science about plant body parts and functions? And third, how to improve the learning outcomes of third-grade students at SDN Tamban Bangun Baru 1 on body parts and plants through the STAD method?The research was carried out in two cycles that were carried out repeatedly with the research subjects being third grade students of SDN Tamban Bangun Baru 1, Tamban District, Barito Kuala Regency. The results showed an increase from cycle I to cycle II. The activity of teachers using the STAD method increased by 86%. Student activity increased with a final score of 80% with very good criteria. This increase can be seen from the test scores at the end of the cycle with a class average of 91% learning completeness of both individual students by 80% with a value of 65 that has been carried out by each student and also an increase in the percentage of students who meet the KKM.Keywords: Student Team Achievement Division, Body Parts of Plant

Clathrin-mediated endocytosis-independent function of VAN3 ARF GTPase Activating Protein at the plasma membrane

ARF small GTPases in plants serve important cellular functions in subcellular trafficking and developmental functions in auxin-mediated patterning of the plant body. The Arabidopsis thaliana ARF regulator ARF-GAP VAN3 has been implicated to act at the plasma membrane (PM) and linked functionally to the clathrin- and dynamin-mediated endocytosis. Here we re-evaluated the localization of VAN3 at the PM and its function in endocytosis. Using Total Internal Reflection Fluorescence microscopy we observed remarkably transient associations of VAN3 to the PM at discrete foci, however, devoid of clathrin, the dynamin isoform DRP1A, or the ARF regulator GNOM, which is also involved in a developmental patterning function mediated from the PM. Clathrin-coated pits are abundant and endocytosis appears to proceed normally in van3-1 knockout mutant. In turn, post-translational silencing of clathrin expression indicates that the localization of VAN3 at the PM depends on clathrin function, presumably on clathrin-mediated endocytosis.

Dialog between Kingdoms: Enemies, Allies and Peptide Phytohormones

Various plant hormones can integrate developmental and environmental responses, acting in a complex network, which allows plants to adjust their developmental processes to changing environments. In particular, plant peptide hormones regulate various aspects of plant growth and development as well as the response to environmental stress and the interaction of plants with their pathogens and symbionts. Various plant-interacting organisms, e.g., bacterial and fungal pathogens, plant-parasitic nematodes, as well as symbiotic and plant-beneficial bacteria and fungi, are able to manipulate phytohormonal level and/or signaling in the host plant in order to overcome plant immunity and to create the habitat and food source inside the plant body. The most striking example of such phytohormonal mimicry is the ability of certain plant pathogens and symbionts to produce peptide phytohormones of different classes. To date, in the genomes of plant-interacting bacteria, fungi, and nematodes, the genes encoding effectors which mimic seven classes of peptide phytohormones have been found. For some of these effectors, the interaction with plant receptors for peptide hormones and the effect on plant development and defense have been demonstrated. In this review, we focus on the currently described classes of peptide phytohormones found among the representatives of other kingdoms, as well as mechanisms of their action and possible evolutional origin.

Meristematic Connectome: A Cellular Coordinator of Plant Responses to Environmental Signals?

Mechanical stress in tree roots induces the production of reaction wood (RW) and the formation of new branch roots, both functioning to avoid anchorage failure and limb damage. The vascular cambium (VC) is the factor responsible for the onset of these responses as shown by their occurrence when all primary tissues and the root tips are removed. The data presented confirm that the VC is able to evaluate both the direction and magnitude of the mechanical forces experienced before coordinating the most fitting responses along the root axis whenever and wherever these are necessary. The coordination of these responses requires intense crosstalk between meristematic cells of the VC which may be very distant from the place where the mechanical stress is first detected. Signaling could be facilitated through plasmodesmata between meristematic cells. The mechanism of RW production also seems to be well conserved in the stem and this fact suggests that the VC could behave as a single structure spread along the plant body axis as a means to control the relationship between the plant and its environment. The observation that there are numerous morphological and functional similarities between different meristems and that some important regulatory mechanisms of meristem activity, such as homeostasis, are common to several meristems, supports the hypothesis that not only the VC but all apical, primary and secondary meristems present in the plant body behave as a single interconnected structure. We propose to name this structure “meristematic connectome” given the possibility that the sequence of meristems from root apex to shoot apex could represent a pluricellular network that facilitates long-distance signaling in the plant body. The possibility that the “meristematic connectome” could act as a single structure active in adjusting the plant body to its surrounding environment throughout the life of a plant is now proposed.

Symmetry reduction in a hyperpolarization-activated homotetrameric ion channel

Plants obtain nutrients from the soil via transmembrane transporters and channels in their root hairs, from which ions radially transport in towards the xylem for distribution across the plant body. We determined structures of the hyperpolarization-activated channel AKT1 from Arabidopsis thaliana, which mediates K+ uptake from the soil into plant roots. These structures of AtAKT1 embedded in lipid nanodiscs show that the channel undergoes a reduction of C4 to C2 symmetry, possibly to regulate its electrical activation.

Leaf Epidermis: The Ambiguous Symplastic Domain

The ability to develop secondary (post-cytokinetic) plasmodesmata (PD) is an important evolutionary advantage that helps in creating symplastic domains within the plant body. Developmental regulation of secondary PD formation is not completely understood. In flowering plants, secondary PD occur exclusively between cells from different lineages, e.g., at the L1/L2 interface within shoot apices, or between leaf epidermis (L1-derivative), and mesophyll (L2-derivative). However, the highest numbers of secondary PD occur in the minor veins of leaf between bundle sheath cells and phloem companion cells in a group of plant species designated “symplastic” phloem loaders, as opposed to “apoplastic” loaders. This poses a question of whether secondary PD formation is upregulated in general in symplastic loaders. Distribution of PD in leaves and in shoot apices of two symplastic phloem loaders, Alonsoa meridionalis and Asarina barclaiana, was compared with that in two apoplastic loaders, Solanum tuberosum (potato) and Hordeum vulgare (barley), using immunolabeling of the PD-specific proteins and transmission electron microscopy (TEM), respectively. Single-cell sampling was performed to correlate sugar allocation between leaf epidermis and mesophyll to PD abundance. Although the distribution of PD in the leaf lamina (except within the vascular tissues) and in the meristem layers was similar in all species examined, far fewer PD were found at the epidermis/epidermis and mesophyll/epidermis boundaries in apoplastic loaders compared to symplastic loaders. In the latter, the leaf epidermis accumulated sugar, suggesting sugar import from the mesophyll via PD. Thus, leaf epidermis and mesophyll might represent a single symplastic domain in Alonsoa meridionalis and Asarina barclaiana.

Extended JAZ degron sequence for plant hormone binding in jasmonate co-receptor of tomato SlCOI1-SlJAZ

Abstract(+)-7-iso-Jasmonoyl-l-isoleucine (JA-Ile) is a lipid-derived phytohormone implicated in plant development, reproduction, and defense in response to pathogens and herbivorous insects. All these effects are instigated by the perception of JA-Ile by the COI1-JAZ co-receptor in the plant body, which in Arabidopsis thaliana is profoundly influenced by the short JAZ degron sequence (V/L)P(Q/I)AR(R/K) of the JAZ protein. Here, we report that SlJAZ-SlCOI1, the COI1-JAZ co-receptor found in the tomato plant, relies on the extended JAZ degron sequence (V/L)P(Q/I)AR(R/K)XSLX instead of the canonical JAZ degron. This finding illuminates our understanding of the mechanism of ligand perception by JA-Ile in this plant, and will inform both efforts to improve it by genetic modification of the SlCOI1-SlJAZ co-receptor, and the development of the synthetic agonists/antagonists.