New advances in the regulation of stem growth in vascular plants

Plant stem growth is important in plant aerial parts and not only affects plant biomass but is also related to plant defense against the external environment. Thus, the regulation of stem growth has attracted increased attention and has been extensively studied. Plant stems require appropriate development to improve their adaptation to various environmental conditions. The stem growth stage can be divided into two parts, stem elongation and stem thickness, which belong to the primary growth and secondary growth of the stem, respectively. The regulatory mechanism is controlled by a sophisticated genetic network including interactions among various molecules, which work individually or coordinate with others. Recently, plant hormones have been reported to be core regulators in stem growth, in combination with other components such as transcription factors and noncoding RNAs. However, few comprehensive overviews of plant stem growth alone have been reported. This review discusses the mechanisms of phytohormones, transcription factors, and noncoding RNAs involved in the regulatory network of main stem growth during the process of primary stem development in vascular plants and provides references for improving plant architecture in the future.