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SUMMARY: The mechanistic basis by which boron (B) deprivation inhibits root growth via the mediation of root apical auxin transport and distribution remains elusive. This study showed that B deprivation repressed root growth of wild‐type Arabidopsis seedlings, which was related to higher auxin accumulation (observed with DII‐VENUS and DR5‐GFP lines) in B‐deprived roots. Boron deprivation elevated the auxin content in the root apex, coinciding with upregulation of the expression levels of auxin biosynthesis‐related genes (TAA1, YUC3, YUC9, and NIT1) in shoots, but not in root apices. Phenotyping experiments using auxin transport‐related mutants revealed that the PIN2/3/4 carriers are involved in root growth inhibition caused by B deprivation. B deprivation not only upregulated the transcriptional levels of PIN2/3/4, but also restrained the endocytosis of PIN2/3/4 carriers (observed with PIN‐Dendra2 lines), resulting in elevated protein levels of PIN2/3/4 in the plasma membrane. Overall, these results suggest that B deprivation not only enhances auxin biosynthesis in shoots by elevating the expression levels of auxin biosynthesis‐related genes but also promotes the polar auxin transport from shoots to roots by upregulating the gene expression levels of PIN2/3/4, as well as restraining the endocytosis of PIN2/3/4 carriers, ultimately resulting in auxin accumulation in root apices and root growth inhibition. Significance Statement: While boron (B) deprivation‐induced root growth inhibition is causally associated with auxin accumulation and transport, the underlying mechanisms remain unknown. This work showed that enhanced auxin biosynthesis resulting from upregulation of the expression levels of auxin biosynthesis‐related genes in shoots and increased protein levels of PIN2/3/4 carriers in the plasma membrane mediated by increased transcript levels of PIN2/3/4 genes in roots combined with restrained endocytosis of PIN2/3/4 carriers result in auxin overaccumulation in root apices and consequently root growth inhibition. [ABSTRACT FROM AUTHOR]

In this paper, we follow the evolutionary origins of cells as unicellular organisms and their evolution towards multicellularity, with a focus on plants and animals, both of which have two basic types of organismal self-identities: the immunological and the neuronal. Most cells of the animal immune system and its mesenchymal tissues are amoeba-like without flagella or cilia and form only loose cell–cell contacts. On the other hand, neuronal and epithelial cells are typically ciliated and assemble epithelial or neuronal synapses. In contrast, walled cells of higher plants lack flagella or cilia. However, lower plants up to the gymnosperm tree Ginkgo biloba have flagellated sperm cells. In our symbiotic concept of eukaryogenesis, the first ancient eukaryotic cells emerged from the merger of a large amoeba-like host cell with a small flagellated guest cell which later transformed into the eukaryotic nucleus. This duality at the origin of the eukaryotic cell matches with the duality of sexual gametes. It also corresponds to the immune system/neural dualities of organismal self-identities in both animals and plants. [ABSTRACT FROM AUTHOR]

We are sympathic with LeDoux's primary goal here ─ to get a solid scientific grip on what has been dubbed one of the most elusive, important questions in scientific discourse, to identify the underlying biomolecular processes that give rise to consciousness. However, we have issues with the way he goes about it and have tried to present them in a constructive manner. Our commentary is built around our theory of the origins of minds, dubbed the Cellular Basis of Consciousness (CBC), and the empirical research that supports it. The CBC is based on the proposition that life and sentience are co-terminous, that life without subjectivity, feeling, without valenced perception, without the capacity to learn and lay down memories would have been an evolutionary dead-end. It could not have survived in the hostile, chaotic world in flux that dominated our planet four billion years ago. The biological sciences operate on the principle that all species, extant and extinct, evolved from the first prokaryotes. The CBC theory is founded on the principle that all expressions of emotion, perception, and cognition did as well. [ABSTRACT FROM AUTHOR]

Vision is essential for most organisms, and it is highly variable across kingdoms and domains of life. The most known and understood form is animal and human vision based on eyes. Besides the wide diversity of animal eyes, some animals such as cuttlefish and cephalopods enjoy so-called dermal or skin vision. The most simple and ancient organ of vision is the cell itself and this rudimentary vision evolved in cyanobacteria. More complex are so-called ocelloids of dinoflagellates which are composed of endocellular organelles, acting as lens- and cornea/retina-like components. Although plants have almost never been included into the recent discussions on organismal vision, their plant-specific ocelli had already been proposed by Gottlieb Haberlandt already in 1905. Here, we discuss plant ocelli and their roles in plant-specific vision, both in the shoots and roots of plants. In contrast to leaf epidermis ocelli, which are distributed throughout leaf surface, the root apex ocelli are located at the root apex transition zone and serve the light-guided root navigation. We propose that the plant ocelli evolved from the algal ocelloids, are part of complex plant sensory systems and guide cognition-based plant behavior. [ABSTRACT FROM AUTHOR]