Sayak Banerjee, Amity University Kolkata
The human body utilizes the veins to transport nutrients and oxygen throughout the whole body. Likewise, plants also have a similar kind of vascular system consisting of highly organized veins which transport nutrients throughout the body. Scientists found that the phytohormone auxin, which has its significance in plant growth and development, not only undergoes directional cell-to-cell transport providing the cell with the positional information of the newly formed veins and their regeneration but also the plant development flexibility in the self-organization of complex patterning during leaf venation and vasculature regeneration around a wound.
The lead scientist explained that auxin decides which cells will differentiate into vascular tissue and arrange them to form complex vein patterns. Polarly localized PIN auxin transport proteins mediate auxin transport. Hence, auxin signalling coordinating the repolarization of PINs in each cell can produce PIN-expressing auxin transport channels that emerge from an artificial local auxin source, revealing that auxin is the essential and sufficient signal for channel formation. Incase cells are unable to sense auxin signal, plant forms deranged veins with separations thus limiting distribution of nutrients.
To understand how the cells, decode this chemical signal into a cellular response, the researchers identified the responsible proteins, called CAMEL (Canalization-related Auxin-regulated Malectin-type RLK) along with CANAR (Canalization-related Receptor-like kinase) which serves as auxin sensor or auxin-regulated receptor. The CAMEL/CANAR complex phosphorylates the PIN auxin transporter and perceives the auxin concentration permitting the cells to organize their orientations to form continuous veins. The auxin feedback coordinates the polarization of individual cells in the course of auxin canalization. Hence, they concluded that it is predominantly a molecular compass for cell orientation which detects auxin concentration, instead of a magnetic field.
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Source: Vol. 370, Issue 6516, pp. 550-557 DOI: 10.1126/scienceaba3178 https://science.sciencemag.org/content/370/6516/550
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