Melatonin Modulates Tomato Root Morphology by Regulating Key Genes and Endogenous Hormones

Abstract

Melatonin plays a vital role in plant growth and development. In this study, we treated hydroponically grown tomato roots with various concentrations of exogenous melatonin (0, 10, 30, and 50 μmol·L−1). We utilized root scanning and microscopy to examine alterations in root morphology and cell differentiation and elucidated the mechanism by which melatonin regulates these changes through the interplay with endogenous hormones and relevant genes. The results showed that for melatonin at concentrations ranging between 10 and 30 μmol·L−1, the development of lateral roots were significantly stimulated, the root hair growth was enhanced, and biomass accumulation and root activity were increased. Furthermore, we elucidated that melatonin acts as a mediator for the expression of genes, such as SlCDKA1, SlCYCA3;1, SlARF2, SlF3H, and SlKT1, which are involved in the regulation of root morphology changes. Additionally, we observed that melatonin influences the levels of endogenous hormones, including ZT, GA3, IAA, ABA, and BR, which subsequently impact the root morphology development of tomato roots. In summary, this study shows that tomato root morphology can be promoted by the optimal concentration of exogenous melatonin (10–30 μmol·L−1).

Melatonin Affects Leymus chinensis Aboveground Growth and Photosynthesis by Regulating Rhizome Growth

“…Plant growth regulators can regulate plant root growth, improve photosynthetic efficiency, delay leaf senescence and alleviate abiotic stress damage [16]. Melatonin can not only effectively regulate the development of plant roots and leaves [17,18], but also affect photosynthetic efficiency and photosynthetic pigment content. For example, under drought stress, melatonin promoted the root system and vitality of cucumber (Cucumis sativus) and increased the root to shoot ratio [19].…”