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— stem cells critical for all post-embryonic tissue growth. The essential role of boron in meristem development was first established in 1923. It remains unclear whether boron directly integrates into meristem molecular signalling pathways. In addition to its stabilizing function in the primary cell wall, growing evidence suggests roles for boron in various molecular processes including phytohormone cascades. These indications 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 (<em>Arabidopsis thaliana</em>), maize (<em>Zea mays</em>), rice (<em>Oryza sativa</em>), and oilseed rape (<em>Brassica napus</em>) 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.