Although the exact role of boron in plants is unknown, several physiological and biochemical activities associated with tissue boron content have been supported experimentally. This review covers some recent work on the role of boron in (1) organic translocation in plants, (2) enzymatic reactions, (3) plant growth regulator response, (4) cell division, (5) cell maturation, (6) nucleic acid metabolism, (7) phenolic acid biosynthesis, and (8) cell wall metabolism. The confusion surrounding the metabolic role of boron in plants has resulted in a "search" for the initial physiological effect of removing boron from the plant environment or, in some cases, adding boron to the plant growth medium or to excise tissue culture. Early plant responses to boron or to its deficiency and other types of experiments have helped clarify boron's role in plant metabolism.^lthough the fact that boron is essential for higher plants has been known for 62 years, a specific single role has never been elucidated; instead a number of roles for boron in plant metabolism have been postu lated (I). Within the past 50 years much research has been directed toward determining the elements physiological role. In recent years, it has become apparent that the "primary" role, if there is just one, may be associated with a biochemical effect of boron in enzymatic reactions or at the nucleic acid biosynthesis level. Much additional work will have to be done before the apparently separate and distinct roles can be brought together into a generally acceptable theory. This review attempts to consolidate some of the recent literature that points out diverse ideas on how boron acts in plant metabolism.
Organic Translocation in PlantsIn 1953 a hypothesis was presented to account for one essential role of boron in plants (2). The authors interpreted their experimental data 112 Downloaded by UCSF LIB CKM RSCS MGMT on December 3, 2014 |