Research Highlights: Some plants stop growing and die after producing fruits, here’s why


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By Stefan.lefnaer – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=47804197

Some plants stop growing and die after producing fruits, here’s why

  • Monocarpic plants are plants that die after producing fruits.
  • When these plants reach certain number of fruits, flower production stops and cells responsible for growth cease dividing.
  • This process of cessation is called proliferative arrest which ensures that nutrient is available for the formation of seeds.
  • Proliferative arrest is an agricultural interest because it influences the flowering time scale and fruit production.
  • The mechanism behind the initiation of the flowering period is well studied.
  • However, the regulatory pathways and cellular processes that take part in the flowering cessation and triggering proliferative arrest is not well understood.
  • Researchers identified the molecular and cellular changes associated with cell division and tissue growth in the shoot apical meristem throughout the flowering time period and proliferative arrest.
  • Shoot apical meristem is the region of a plant that contains multipotent stem cells responsible for the development of plant organs above the ground.[1]
  • Researchers discovered that before proliferative arrest occurs, cytokinin signaling was suppressed.
  • Cytokinin is a plant hormone that induces cytokinesis or plant growth.[2]
  • Additionally, researchers observed that repression of type B cyclins and WUSCHEL is correlated with proliferative arrest.
  • B cyclins are proteins involved in the process of cell cycle.[3]
  • WUSCHEL is a master regulator involved in plant growth signaling.[4]
  • These molecular changes were observed to go along with changes in cell number and size.
  • A separate analysis revealed that a mutation in FUL does not trigger proliferative arrest.
  • FUL is the gene associated with controlling flowering time, meristem identity and leaf formation.[5]
  • The study determined two phases that lead to proliferative arrest: early reduction and late blocking of cytokinin-related events.

Sources:

Paz Merelo et al. (2021). A cellular analysis of meristem activity at the end of flowering points to cytokinin as a major regulator of proliferative arrest in Arabidopsis, Current Biology. DOI: 10.1016/j.cub.2021.11.069

[1] https://www.nature.com/subjects/shoot-apical-meristem

[2] https://en.wikipedia.org/wiki/Cytokinin

[3] https://en.wikipedia.org/wiki/Cyclin_B

[4] https://link.springer.com/article/10.1007/s00299-020-02511-5

[5] https://pubmed.ncbi.nlm.nih.gov/21284215


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Research Highlights: Where we plant coffee, cashew, and avocado right now may not be suitable in the future


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black coffee fruit picked during daytime
Photo by mali maeder on Pexels.com

Where we plant coffee, cashew, and avocado right now may not be suitable in the future

  • Coffee, cashew, and avocado are among the most important cash crops and possess importance in the economy.
  • Coffee beans are used in many beverages and drink products.
  • Cashew seeds are commonly consumed as snack nuts.
  • Avocados are used as ingredient to many food items.
  • Coffee, cashew, and avocado are plantation crops with a long lifespan of several decades and their cultivation requires long-term planning.
  • The Intergovernmental Panel on Climate Change predicted that the global temperature will be 1.2 to 3.0°C higher by year 2050.
  • Scientists highlight the importance of evaluating the impact of climate change on the plants biophysical suitability in order to develop adaptation measures and selecting appropriate varieties of crops.
  • Researchers created model of the current and future suitability of these plants on a global scale based on climate and soil requirement.
  • They model the year 2050 climate change impact on the crops both globally and in the countries mainly producing the crops.
  • Researchers discovered that climate factors including long dry season, mean temperatures, low minimum temperatures, and yearly precipitation reduce the suitability of growing these crops more than land and soil factors which include soil pH, texture, and slope steepness.
  • They predicted that there will be shifts in suitable growing regions due to global warming.
  • Coffee will be the most susceptible with negative climate impacts highly expected in all main producing regions which include Brazil, Vietnam, Indonesia and Colombia.
  • Areas suitable for cultivating cashew and avocado are expected to expand globally; however, most main producing countries will experience decrease in suitability.
  • The main cashew-producing countries include Vietnam, India, Côte d’Ivoire and Benin, while the main avocado-producing countries include Mexico, the Dominican Republic, Peru and Indonesia.
  • The study highlights the importance of climate change adaptation in most major producing regions of all the three crops.
  • Areas with lower temperature such as in high latitudes and altitudes may profit from increasing minimum temperatures.
  • The study shows the first global evaluation of the impacts of climate change on cashew and avocado suitability.

Source:

Grüter R, Trachsel T, Laube P, Jaisli I (2022) Expected global suitability of coffee, cashew and avocado due to climate change. PLoS ONE 17(1): e0261976. https://doi.org/10.1371/journal.pone.0261976


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Research Highlights: Broccoli Contains Compound That Can Kill Yeast


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green broccoli vegetable on brown wooden table
Photo by Pixabay on Pexels.com

Broccoli Contains Compound That Can Kill Yeast

  • Broccoli is a common edible green plant in the family Brassicaceae with all of the parts eaten as vegetable.[1]
  • A compound called 3,3’-diindolylmethane or DIM can be obtained from the digestion of indole-3-carbinol, found in broccoli.
  • DIM promotes cell death and autophagy in some human cancer.
  • Autophagy refers to the natural process of cell degradation by which unnecessary or non-functional cellular components are removed or recycled.
  • DIM extends lifespan in the yeast called Schizosaccharomyces pombe.
  • S. pombe, often called fission yeast, is a species of yeast used in traditional brewing.[3]
  • However, the way by which DIM promotes cell destruction in humans and extends lifespan in S. pombe are not very well understood.
  • Researchers show that DIM promotes cell destruction in log-phase cells which is dose-dependent.
  • .Log-phase is the period by which cells exponentially increase in number.
  • Researchers discovered that when high concentration of DIM was added, the cell’s nuclear envelope was disrupted and the chromosome tightly packed at an early stage.
  • On the other hand, when low concentration of DIM was added, cells were degraded but did not cause disruption on the nuclear envelope.
  • Cells defective in autophagy were more vulnerable to the low concentration of DIM which suggest the autophagic pathway contributes to the cell’s survival against DIM.
  • Additionally, researchers discovered that the cells with lem2 mutation are more sensitive to DIM.
  • Lem2 is a protein that regulates the size of the cell’s nuclear envelope.[2]
  • The nuclear envelope of cells with lem2 mutation was disrupted even at low DIM concentration.
  • The results highlight the importance of autophagic pathway and nuclear envelope integrity in maintaining cell viability during exposure to low DIM concentration.
  • Researchers speculated that the process of cell death and autophagy induce by DIM are conserved in humans and S. pombe.
  • Future studies are needed to understand more about the DIM being able to induce cell death and autophagy in humans and S. pombe.

Sources:

Emami P, Ueno M (2021) 3,3’-Diindolylmethane induces apoptosis and autophagy in fission yeast. PLoS ONE 16(12): e0255758. https://doi.org/10.1371/journal.pone.0255758

[1] https://en.wikipedia.org/wiki/Broccoli

[2] https://www.nature.com/articles/s41467-019-09623-x

[3] https://en.wikipedia.org/wiki/Schizosaccharomyces_pombe


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Research Highlights: Plant’s Glowing Properties Produce Stunning Images of Microscopic Structures


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Plant’s Glowing Properties Produce Stunning Images of Microscopic Structures

  • Microscopic staining has been used to enhance the visualization of samples at the microscopic level.
  • Before viewing samples under a microscope, cells and tissues must be stained which requires long preparation processes.
  • Another way to improve cellular visualization is by utilizing fluorescence tagging.
  • A fluorescence tag is a molecule that attaches to detect proteins, antibodies, and amino acids.[1]
  • Many research studies utilize fluorescence microscopy to view plant internal structures.
  • However, throughput can be hindered by using fluorescent antibodies or labels.
  • Researchers proposed a minimal protocol that uses existing autofluorescence and aldehyde-induced fluorescence in plant structures to improve throughput in visualization.
  • Researchers subjected twelve species to five fixative treatments.
  • The following five fixative treatments are 1% paraformaldehyde and 2% glutaraldehyde, 2% paraformaldehyde, 2% glutaraldehyde, formalin-acid-alcohol, and 70% ethanol.
  • Researchers used a confocal laser scanning system to collect images seen by a microscope.
  • Researchers compared fixative influence on plant sample structural preservation and autofluorescence of tissues.
  • Viridiplantae or green plant samples treated with formaldehyde produced useful structural data without requiring additional histological staining.
  • Additionally, a microscope capable of fluorescence is the only equipment required for acquiring such images.
  • The protocol allows for a high-throughput sample processing by obsoleting multiple-day preparations.

Sources:

Pegg, T. J., Gladish, D. K., and Baker, R. L.. 2021. Algae to angiosperms: Autofluorescence for rapid visualization of plant anatomy among diverse taxa. Applications in Plant Sciences 9( 6): e11437. https://doi.org/10.1002/aps3.11437

[1] https://en.wikipedia.org/wiki/Fluorescent_tag


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Research Highlights: Bacterial Protein Makes “Zombie” Plant


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Photo courtesy of Whitney Cranshaw, Colorado State University, Bugwood.org

Bacterial Protein Makes “Zombie” Plant

  • Obligate parasite is an organism that completes its life-cycle by exploiting a suitable host.
  • Some obligate parasites induce significant observable changes in their hosts which allows the parasites to be transmitted easily to other trophic levels.
  • However, the mechanisms underlying these changes are not well understood.
  • Researchers demonstrated how bacterial protein SAP05 from pathogenic phytoplasmas transmitted by insect take control of numerous developmental processes in plants.
  • Protein effectors are small molecules that selectively bind to a protein and modulate its biological activity.[2]
  • Phytoplasma is an obligate intracellular parasite of plant phloem tissue.[3]
  • Phytoplasma lacks cell wall and mainly transmitted by leafhoppers but also by plant propagation materials and seeds.[4]
  • These protein effectors make the host lifespan longer and promote witches’ broom-like growth of leaf and sterile shoots, parts colonized by phytoplasmas and vectors.
  • Normally, proteins not needed by plants are tagged with ubiquitin marking them as to be degraded.
  • A machinery called proteasome then degrades the tagged proteins for recycling.
  • SAP05 hijacks the protein degradation process and causes plant proteins involved in regulating growth to be degraded.
  • SAP05 binds to both regulatory protein and the proteasome facilitating the degradation of these protein.
  • Without these regulatory proteins, plant growth is affected which results in multiple vegetative shoot and tissue growth and suspension of plant aging.
  • Ubiquitin receptor is common among eukaryotic organisms; however, SAP05 does not bind to insect ubiquitin receptor.
  • Researchers pinpointed two amino acids in proteasome that are required to interact with SAP05.
  • If these two amino acids in plant protein are replaced with amino acids from insect protein instead, they no longer interact with SAP05 and prevents the witches’ broom abnormal growth.
  • The study highlights an effector protein that enables obligate parasitic phytoplasmas to promote an excess of growth development in their hosts.
  • The new findings offer the possibility of manipulating two amino acids in crops to provide long-lasting resilience against phytoplasmas and the effect of SAP05.

Related Video

Sources:

https://doi.org/10.1016/j.cell.2021.08.029

https://www.jic.ac.uk/press-release/the-microbial-molecule-that-turns-plants-into-zombies

[2] https://en.wikipedia.org/wiki/Effector_(biology)

[3] https://en.wikipedia.org/wiki/Phytoplasma

[4] https://www.frontiersin.org/articles/10.3389/fmicb.2019.01349/full


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