title: Melatonin Regulates Root Meristem by Repressing Auxin Synthesis and Polar Auxin Transport inArabidopsis.
abstract: Melatonin (N-acetyl-5-methoxytryptamine) plays important roles in regulating both biotic and abiotic stress tolerance, biological rhythms, plant growth and development. Sharing the same substrate (tryptophan) for the biosynthesis, melatonin and auxin also have similar effects in plant development. However, the specific function of melatonin in modulating plant root growth and the relationship between melatonin and auxin as well as underlying mechanisms are still unclear. In this study, we found high concentration of melatonin remarkably inhibited root growth inArabidopsisby reducing root meristem size. Further studies showed that melatonin negatively regulated auxin biosynthesis, the expression of PINFORMED (PIN) proteins as well as auxin response inArabidopsis. Moreover, the root growth of the triple mutantpin1pin3pin7was more tolerant than that of wild-type in response to melatonin treatment, suggesting the essential role of PIN1/3/7 in melatonin-mediated root growth. Combination treatment of melatonin and 5-Triiodobenzoic acid (TIBA) did not enhance melatonin-mediated reduction of root meristem size, indicating that polar auxin transport (PAT) may be necessary for the regulation of root meristem size by melatonin treatment. Taken together, this study indicates that melatonin regulates root growth inArabidopsis, through auxin synthesis and polar auxin transport, at least partially.
authors.affiliation: Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University Haikou, China.
authors.forename: Qiannan
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University Haikou, China.
authors.forename: Bang
authors.initials: B
authors.lastname: An
authors.affiliation: Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University Haikou, China.
authors.forename: Yunxie
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Department of Cell Systems and Anatomy, The University of Texas Health Science Center San Antonio, TX, USA.
authors.forename: Russel J
authors.initials: RJ
authors.lastname: Reiter
authors.affiliation: Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University Haikou, China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Shi
authors.affiliation: Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University Haikou, China.
authors.forename: Hongli
authors.initials: H
authors.lastname: Luo
authors.affiliation: Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Agriculture, Hainan University Haikou, China.
authors.forename: Chaozu
authors.initials: C
authors.lastname: He
keywords: Arabidopsis; auxin; auxin synthesis; melatonin; polar auxin transport; root meristem