Crosstalk Between Ethylene and Cytokinin in Arabidopsis thaliana

Abstract

Plant hormones regulate the growth and development of plants throughout their life. Plants change their growth pattern to adjust according to the external environment. This change is controlled by the crosstalk of different hormones present in the plants. Ethylene is one of the most important hormones present in plants. It controls several developmental processes in plants that include senescence, abscission of leaves, ripening of fruits, defense against pathogenic attack, and stress conditions. It regulates the growth patterns of plants by interacting with other hormones. Crosstalk of hormones in the development of the root system of plants is critical. The development of the primary root greatly depends on the regulation of the proliferation of cells and the elongation/differentiation of cells in the root. Ethylene is known to inhibit the elongation of cells in the roots. Our study finds the role of ethylene in inhibiting the proliferation of cells in the root meristem. Ethylene reduces the number of cells in the cortex layer of the root apical meristem. Wild-type Arabidopsis thaliana shows a reduced meristem in ethylene response. Insensitive mutants of ethylene show no reduction in the root meristem. Real-time data shows that the reduction in root meristem by ethylene is due to shy2. Shy2 inhibits RAM in response to ethylene exactly in the same manner as it does in response to cytokinin. Ethylene and cytokinin both inhibit the proliferation of cells in the root apical meristem. Our study indicates the interaction of ethylene and cytokinin and the recruitment of ARR by ethylene via the histidine kinase receptor of ETR1. Concurrent treatment of ethylene and cytokinin induced a subtractive and additive effect on the expression of cytokinin and ethylene induced genes in wild type. Based on this, we predict that ARRs regulate a subset of ethylene responses, doing so through interaction with the EIN3 family of transcription factors. The use of pharmacological agent 1-MCP recovered the reduced size of the meristem indicating the role of ethylene in inhibiting root apical meristem. Our study also provides the agricultural benefits of 1-MCP. 1-MCP delayed the ripening of tomatoes and prolonged the storage period of tomatoes. Physiological parameters like color, firmness, and weight were maintained with 1-MCP for a longer period. Ripening-related genes RIN, CNR, NOR, and PSY were downregulated in response to 1-MCP. 1-MCP treatment improves the quality of tomatoes for longer periods and is useful for longer storage and transportation. The ripening effect of ethylene can be delayed by the use of 1-MCP.