The diverse roles of cytokinins in regulating leaf development

Abstract

Leaves provide energy for plants, and consequently for animals, through photosynthesis. Despite their important functions, plant leaf developmental processes and their underlying mechanisms have not been well characterized. Here, we provide a holistic description of leaf developmental processes that is centered on cytokinins and their signaling functions. Cytokinins maintain the growth potential (pluripotency) of shoot apical meristems, which provide stem cells for the generation of leaf primordia during the initial stage of leaf formation; cytokinins and auxins, as well as their interaction, determine the phyllotaxis pattern. The activities of cytokinins in various regions of the leaf, especially at the margins, collectively determine the final leaf morphology (e.g., simple or compound). The area of a leaf is generally determined by the number and size of the cells in the leaf. Cytokinins promote cell division and increase cell expansion during the proliferation and expansion stages of leaf cell development, respectively. During leaf senescence, cytokinins reduce sugar accumulation, increase chlorophyll synthesis, and prolong the leaf photosynthetic period. We also briefly describe the roles of other hormones, including auxin and ethylene, during the whole leaf developmental process. In this study, we review the regulatory roles of cytokinins in various leaf developmental stages, with a focus on cytokinin metabolism and signal transduction processes, in order to shed light on the molecular mechanisms underlying leaf development.

Role of the type‐B authentic response regulator gene family in fragrant rice under alkaline salt stress

“…In previous studies it is reported that, the HK3, HK4, and HK6 are cytokinin histidine kinase receptor related proteins, and WOX11 is the transcription factor involved in developmental processes. Similarly, CKX4 (cytokinin dehydrogenase) is a key enzyme involved in the catalyzation of the oxidation of cytokinin (Burr et al, 2020; Chen et al, 2020; Jiang et al, 2017; Wu et al, 2021). An in silico protein–protein interaction was performed among the OsARR‐B members and other cytokinin coregulatory proteins (Figure 6A and S1 and Table S4).…”

Comparative transcriptomic analysis reveals the molecular mechanism underlying seedling biomass heterosis in Brassica napus

“…Cytokinins play a crucial role in regulating plant growth and development. They can promote the proliferation and expansion of leaf cell development and coordinate with auxins to regulate plant growth [ 32 ]. In our study, two genes related to the response regulation of Arabidopsis were upregulated in strongly dominant hybrids.…”

Stress mitigation strategies of plant growth-promoting rhizobacteria: Plant growth-promoting rhizobacteria mechanisms

“…Some of the PGPR which synthesize cytokinin includes Pseudomonas stutzeri, Stenotrophomonas maltophilia and P. putida. Cytokinin is involved in the maintenance of plant cell division in culture and in various differentiation processes such as primary root growth, callus formation and shoot formation (43,44). Totipotency is the distinguishing feature of cytokinin from other plant growth regulators, which helps to maintain totipotent stem cells in their root and shoot meristem.…”