Tracing boron dynamics in agro-ecosystems using enriched (10B, 11B) stable isotopic signatures: A centennial legacy

For many years after the discovery of the two stable isotopes of B (10B,11B) in 1920 it was not used routinely as a tracer in the biological sciences until the development of inductively coupled plasma mass spectrometry in the early 1980s. This development provided an impetus to the study of the role of B in plant nutrition, although many seminal discoveries were made beforehand without the aid of isotopes. Thus, much information on the mobility and physiological function of B in plants is post-1985. Boron is unusual in plant nutrition in that it is taken up by plants through roots or foliage as undissociated boric acid, unlike other essential elements that are taken up in ionic form. The within-plant mobility of B in species important in agriculture and horticulture is examined in the present review including the role of sugar alcohols in xylem to phloem transfer. The molecular basis of its movement at the cellular level via transporters as revealed through the strategic application of enriched 11B and 10B is addressed. Few studies have been carried out on B use efficiency by crops and results show great variability. Suggestions for future applications of tracing with 10B and 11B are provided.