Two-spot spider mite (yellow form), Tetranychus urticae
To start at the beginning because that's always a good place to start, plants need to get water and nutrients up to their leaves, so their 'designer' gave them a vascular system but without a pump, so, to maintain the upward flow, they need to evaporate away (or transpire) the water that just arrived in their leaves. They do this through tiny pores (or stomata; singular=stoma) that are just about visible to the naked eye, and clearly visible under a hand lens or a microscope.
These stomata are guarded by guard cells, one on either side, which can swell to close the stoma or shrink to allow the stoma to open, as the need arises.
However, these stomata are an open invitation to sap-sucking arthropods such as mites and aphids, which are cleverly designed, reputedly by the same designer that designed the stomata, which can push their mouthparts into the stoma to get at the nutrient-rich watery contents of the leaf.
So, having designed these sap-suckers to exploit the transport system it designed for plants, creationism's putative designer clearly saw the sap-suckers it had designed as a problem to be solved.
How it added this Heath-Robinson layer of additional complexity to solve the problem the earlier layer of complexity had caused is the subject of a research paper by a collaboration of researchers from the Centre for Plant Biotechnology and Genomics (CBGP), Spain, and Sainsbury Laboratory, Cambridge University (SLCU), Cambridge, UK and a news release from Cambridge University:
Plants utilise drought stress hormone to block snacking spider mites
Recent findings that plants employ a drought-survival mechanism to also defend against nutrient-sucking pests could inform future crop breeding programmes aimed at achieving better broadscale pest control.
Using an advanced fluorescent biosensor (ABACUS2) that can detect tiny changes in plant hormone concentrations at the cellular scale, scientists saw that abscisic acid (ABA), usually linked with drought response, started closing the plant’s entry gates within 5 hours of being infested with spider mites.
Microscopic leaf pores (stomata) are important for gas exchange but are also the major sites for water loss. When there is a water shortage, plants act to conserve water by producing the drought stress hormone ABA to close their stomata.
Coincidentally, the closure of stomata also obstructs the preferred entry points for nutrient-sucking pests like spider mites. The two-spotted spider mite is one of the most economically damaging pests – it’s not fussy and attacks a broad range of more than 1000 plants, including 150 crops. Barely visible to the naked eye, these tiny pests pierce and then suck dry plant cells. They can build up to enormous numbers very quickly and can be one of the most destructive pests in the garden and horticulture industry, spoiling house plants and reducing yields of vegetables, fruit and salad crops.
There has been debate about ABA's role in pest resistance. Initially, it was noticed that stomata close when plants are attacked by nutrient-sucking pests, leading to various hypotheses, including that this closure could be a plant response to losing water due to the pests' feeding or even that the pests act to close stomata to prevent plants from sending distress volatiles to pest predators.
In a collaboration between the Centre for Plant Biotechnology and Genomics (CBGP) in Spain and Sainsbury Laboratory Cambridge University (SLCU), researchers studying how thale cress (Arabidopsis thaliana) responds to the two-spotted spider mite (Tetranychus urticae) have determined the plant leaps into action almost immediately, employing the same hormone as for drought to also block spider mites from penetrating plant tissues and, as a result, significantly reducing pest damage.
The findings published in Plant Physiology found the peak closure of stomata is achieved within a time frame of 24 to 30 hours.
“Open stomata are natural apertures where pests like aphids and mites insert their specialised feeding structures, called stylets, to pierce and then suck out the nutrient rich contents from individual sub-epidermal cells”, said Irene Rosa-Díaz, who carried out the spider mite experiments at SLCU and CBGP during her PhD with Professor Isabel Diaz at the Centro de Biotecnología y Genómica de Plantas, Universidad Polytécnica de Madrid, and National Institute of Agricultural and Food Research and Technology (UPM-INIA).
Alexander Jones’ research group at SLCU develops in vivo biosensors that are revealing hormone dynamics in plants at unprecedented resolution, including ABACUS2 that quantified cellular ABA in these mite experiments.
Dr Jones said the study highlights the important interactions between biotic and abiotic stresses in plants:
Recent findings that plants employ a drought-survival mechanism to also defend against nutrient-sucking pests could inform future crop breeding programmes aimed at achieving better broadscale pest control.
Using an advanced fluorescent biosensor (ABACUS2) that can detect tiny changes in plant hormone concentrations at the cellular scale, scientists saw that abscisic acid (ABA), usually linked with drought response, started closing the plant’s entry gates within 5 hours of being infested with spider mites.
Microscopic leaf pores (stomata) are important for gas exchange but are also the major sites for water loss. When there is a water shortage, plants act to conserve water by producing the drought stress hormone ABA to close their stomata.
Coincidentally, the closure of stomata also obstructs the preferred entry points for nutrient-sucking pests like spider mites. The two-spotted spider mite is one of the most economically damaging pests – it’s not fussy and attacks a broad range of more than 1000 plants, including 150 crops. Barely visible to the naked eye, these tiny pests pierce and then suck dry plant cells. They can build up to enormous numbers very quickly and can be one of the most destructive pests in the garden and horticulture industry, spoiling house plants and reducing yields of vegetables, fruit and salad crops.
There has been debate about ABA's role in pest resistance. Initially, it was noticed that stomata close when plants are attacked by nutrient-sucking pests, leading to various hypotheses, including that this closure could be a plant response to losing water due to the pests' feeding or even that the pests act to close stomata to prevent plants from sending distress volatiles to pest predators.
The findings published in Plant Physiology found the peak closure of stomata is achieved within a time frame of 24 to 30 hours.
“Open stomata are natural apertures where pests like aphids and mites insert their specialised feeding structures, called stylets, to pierce and then suck out the nutrient rich contents from individual sub-epidermal cells”, said Irene Rosa-Díaz, who carried out the spider mite experiments at SLCU and CBGP during her PhD with Professor Isabel Diaz at the Centro de Biotecnología y Genómica de Plantas, Universidad Polytécnica de Madrid, and National Institute of Agricultural and Food Research and Technology (UPM-INIA).
We were able to show mite infestation induced a rapid stomatal closure response, with the plant hormone ABA rising in the leaf tissues – highest in stomatal and vascular cells, but also all other leaf cells measured. We showed through multiple different experiments that stomatal closure hinders mites. Plants that were pre-treated with ABA to induce stomatal closure and then infested with mites showed decreased mite damage, while ABA-deficient mutant plants where stomata cannot close well and plants that have a more stomata are more susceptible to mites.
Irene Rosa-Diaz, lead author
Centro de Biotecnología y Genómica de Plantas (CBGP)
Universidad Politécnica de Madrid, Spain.
Universidad Politécnica de Madrid, Spain.
Dr Jones said the study highlights the important interactions between biotic and abiotic stresses in plants:
Early warning cues from mite feeding induces a cascade of immune signalling molecules, including jasmonic acid (JA) and salicylic acid (SA), among other chemical responses. Together, these results show that ABA accumulation and stomatal closure are also key defence mechanisms employed to reduce mite damage.
The next step is to investigate what the initial mite-produced signal is that the plant is detecting that then results in ABA accumulation. The biochemical mechanisms being used by the plant as signals of pest attack could be anything, including mite feeding vibrations, mite salivary proteins, chemicals produced by the mites or mite activity, direct cell damage (wounds) or other molecules associated with the mites.
Identifying the initial triggers could potentially be used to develop new crop treatments to arm the plants ahead of predicted pest infestations. Importantly, efforts to select for plants with altered stomatal traits, which already must balance a photosynthesis vs water conservation trade-off, could also consider resistance to damaging pests.
Alexander M Jones, corresponding author
Sainsbury Laboratory
Cambridge University, Cambridge, UK.
Sainsbury Laboratory
Cambridge University, Cambridge, UK.
AbstractOf course, we can almost guarantee that any solution to the problem these mites are causing us in the shape of reduced crops and increased plant diseases, will fairly quickly have a solution to the problem our solution causes the mite, as there is nothing more that creationism's putative intelligent [sic] designer likes more than an arms race with science when it isn't stupidly having an arms race with itself.
Arthropod herbivory poses a serious threat to crop yield, prompting plants to employ intricate defense mechanisms against pest feeding. The generalist pest 2-spotted spider mite (Tetranychus urticae) inflicts rapid damage and remains challenging due to its broad target range. In this study, we explored the Arabidopsis (Arabidopsis thaliana) response to T. urticae infestation, revealing the induction of abscisic acid (ABA), a hormone typically associated with abiotic stress adaptation, and stomatal closure during water stress. Leveraging a Forster resonance energy transfer (FRET)-based ABA biosensor (nlsABACUS2-400n), we observed elevated ABA levels in various leaf cell types postmite feeding. While ABA's role in pest resistance or susceptibility has been debated, an ABA-deficient mutant exhibited increased mite infestation alongside intact canonical biotic stress signaling, indicating an independent function of ABA in mite defense. We established that ABA-triggered stomatal closure effectively hinders mite feeding and minimizes leaf cell damage through genetic and pharmacological interventions targeting ABA levels, ABA signaling, stomatal aperture, and density. This study underscores the critical interplay between biotic and abiotic stresses in plants, highlighting how the vulnerability to mite infestation arising from open stomata, crucial for transpiration and photosynthesis, reinforces the intricate relationship between these stress types.
The Unintelligent Designer: Refuting The Intelligent Design Hoax
ID is not a problem for science; rather science is a problem for ID. This book shows why. It exposes the fallacy of Intelligent Design by showing that, when examined in detail, biological systems are anything but intelligently designed. They show no signs of a plan and are quite ludicrously complex for whatever can be described as a purpose. The Intelligent Design movement relies on almost total ignorance of biological science and seemingly limitless credulity in its target marks. Its only real appeal appears to be to those who find science too difficult or too much trouble to learn yet want their opinions to be regarded as at least as important as those of scientists and experts in their fields.
Available in Hardcover, Paperback or ebook for Kindle
The Malevolent Designer: Why Nature's God is Not Good
This book presents the reader with multiple examples of why, even if we accept Creationism's putative intelligent designer, any such entity can only be regarded as malevolent, designing ever-more ingenious ways to make life difficult for living things, including humans, for no other reason than the sheer pleasure of doing so. This putative creator has also given other creatures much better things like immune systems, eyesight and ability to regenerate limbs that it could have given to all its creation, including humans, but chose not to. This book will leave creationists with the dilemma of explaining why evolution by natural selection is the only plausible explanation for so many nasty little parasites that doesn't leave their creator looking like an ingenious, sadistic, misanthropic, malevolence finding ever more ways to increase pain and suffering in the world, and not the omnibenevolent, maximally good god that Creationists of all Abrahamic religions believe created everything. As with a previous book by this author, "The Unintelligent Designer: Refuting the Intelligent Design Hoax", this book comprehensively refutes any notion of intelligent design by anything resembling a loving, intelligent and maximally good god. Such evil could not exist in a universe created by such a god. Evil exists, therefore a maximally good, all-knowing, all-loving god does not.
Illustrated by Catherine Webber-Hounslow.
Available in Hardcover, Paperback or ebook for Kindle
Illustrated by Catherine Webber-Hounslow.
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