title: Local melatonin application induces cold tolerance in distant organs of Citrullus lanatus L. via long distance transport.
abstract: Melatonin is a ubiquitous chemical substance that regulates plant growth and responses to stress. Several recent studies show that exogenous melatonin confers cold tolerance to plants; however, the underlying mechanisms remain largely unknown. Here, we report that melatonin application at optimal dose, either on the leaves or the roots, not only induced cold stress tolerance in the site of application, but also systemically induced cold tolerance in untreated distant parts. Foliar or rhizospheric treatment with melatonin increased the melatonin levels in untreated roots or leaves, respectively, under both normal and cold stress conditions, whereas rhizospheric melatonin treatment increased the melatonin exudation rates from the xylem. An increased accumulation of melatonin accompanied with an induction in antioxidant enzyme activity in distant untreated tissues alleviated cold-induced oxidative stress. In addition, RNA-seq analysis revealed that an abundance of cold defense-related genes involved in signal sensing and transduction, transcriptional regulation, protection and detoxification, and hormone signaling might mediate melatonin-induced cold tolerance. Taken together, our results suggest that melatonin can induce cold tolerance via long distance signaling, and such induction is associated with an enhanced antioxidant capacity and optimized defense gene expression. Such a mechanism can be greatly exploited to benefit the agricultural production.
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Chang
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Junxian
authors.initials: J
authors.lastname: Zheng
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Yuchuan
authors.initials: Y
authors.lastname: Dong
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Qiyan
authors.initials: Q
authors.lastname: Liu
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Xiaozhen
authors.initials: X
authors.lastname: Yang
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Wei
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Jianxiang
authors.initials: J
authors.lastname: Ma
authors.affiliation: College of Horticulture, Northwest A&F University, Taicheng Road 3, Yangling 712100, Shaanxi, P.R. China.
authors.forename: Xian
authors.initials: X
authors.lastname: Zhang
mesh_terms: D029773:Citrullus / Q000254:growth & development* / Q000378:metabolism; D003080:Cold Temperature; D008315:Malondialdehyde / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects* / Q000235:genetics; D010088:Oxidoreductases / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome / Q000187:drug effects; D052584:Xylem / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors; D008315:Malondialdehyde; D010088:Oxidoreductases; D008550:Melatonin