Physiological and genetic responses to boron deficiency in Brassica napus: A review

Boron (B) is an essential microelement for the growth and development of plants, and B deficiency affects many biochemical and physiological processes. Brassica napus L. has a high demand for B and is extremely sensitive to B deficiency. Seed yields and oil quality of B. napus are often limited by the low availability of B in soils. Developing new cultivars of B. napus with high B efficiency is therefore required, which requires a greater understanding of responses to B deficiency. Significant genotypic differences in response to low soil B have been observed among varieties of B. napus. B-efficient genotypes can grow and yield normally and usually have a larger root system than B-inefficient genotypes at low B conditions. The mechanisms for B efficiency in B. napus are attributed to B absorption, transportation and utilization. In addition, the cell wall component plays an important role in the tolerance of B. napus to B deficiency, and the B-efficient line presents fewer B-binding sites in the cell walls compared with the B-inefficient line. Genetic and proteomic analyses in B. napus revealed the modulation of a complex network in response to B deficiency. This review gives a comparative overview of the physiological and genetic responses to B deficiency in B. napus and discusses the possible underlying mechanisms of B efficiency.