Use of phenylboronic acids to investigate boron function in plants. Possible role of boron in transvacuolar cytoplasmic strands and cell-to-wall adhesion.
The only defined physiological role of boron in plants is as a cross-linking molecule involving reversible covalent bonds with cis-diols on either side of borate. Boronic acids, which form the same reversible bonds with cis-diols but cannot cross-link two molecules, were used to selectively disrupt boron function in plants. In cultured tobacco (Nicotiana tabacum cv BY-2) cells, addition of boronic acids caused the disruption of cytoplasmic strands and cell-to-cell wall detachment. The effect of the boronic acids could be relieved by the addition of boron-complexing sugars and was proportional to the boronic acid-binding strength of the sugar. Experiments with germinating petunia (Petunia hybrida) pollen and boronate-affinity chromatography showed that boronic acids and boron compete for the same binding sites. The boronic acids appear to specifically disrupt or prevent borate-dependent cross-links important for the structural integrity of the cell, including the organization of transvacuolar cytoplasmic strands. Boron likely plays a structural role in the plant cytoskeleton. We conclude that boronic acids can be used to rapidly and reversibly induce boron deficiency-like responses and therefore are useful tools for investigating boron function in plants.
Bassil
Elias
E
Pomology Department, University of California, Davis, California 95616, USA.
Hu
Hening
H
Brown
Patrick H
PH
D000268:Adhesiveness / Q000187:drug effects; D001693:Biological Transport, Active; D001895:Boron / Q000378:metabolism / Q000502:physiology*; D001897:Boronic Acids / Q000494:pharmacology*; D002473:Cell Wall / Q000187:drug effects; D022083:Cytoplasmic Structures / Q000187:drug effects*; D006023:Glycoproteins / Q000187:drug effects / Q000378:metabolism; D032306:Petunia / Q000648:ultrastructure; D010940:Plant Proteins / Q000187:drug effects / Q000378:metabolism; D010944:Plants / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure*; D011058:Pollen / Q000187:drug effects; D014026:Nicotiana / Q000648:ultrastructure
D001897:Boronic Acids; D006023:Glycoproteins; D010940:Plant Proteins; C010686:benzeneboronic acid; D001895:Boron