Molecular mechanisms affected by boron deficiency in root and shoot meristems of plants.

Abstract

Boron deficiency is an abiotic stress that negatively impacts plant growth and yield worldwide. Boron deficiency primarily affects the development of plant meristems, groups of stem cells critical for all postembryonic tissue growth. The link between boron and meristem development was first established in 1923, when boron's essentiality was discovered. It remains, however, unclear whether boron directly integrates into molecular meristem pathways. In addition to its stabilizing function in the primary cell wall, growing evidence suggests roles of boron in various molecular processes including phytohormone cascades. These indications help enhance a mechanistic understanding of why boron is crucial for proper meristem development. In this review we compile and discuss molecular pathways influenced by boron availability in Arabidopsis (Arabidopsis thaliana), maize (Zea mays), rice (Oryza sativa), and oilseed rape (Brassica napus) with a focus on the auxin-, ethylene-, and cytokinin-mediated hormone cascades. We particularly compare and contrast phenotypic and molecular adaptations of shoot and root meristems to boron deficiency and pinpoint tissue-specific differences.