title: An ethylene and ROS-dependent pathway is involved in low ammonium-induced root hair elongation in Arabidopsis seedlings.
abstract: Root hairs are plastic in response to nutrient supply, but relatively little is known about their development under low ammonium (NH4(+)) conditions. This study showed that reducing NH4(+) for 3 days in wild-type Arabidopsis seedlings resulted in drastic elongation of root hairs. To investigate the possible mediation of ethylene and auxin in this process, seedlings were treated with 2,3,5-triiodobenzoic acid (TIBA, auxin transport inhibitor), 1-naphthylphthalamic acid (NPA, auxin transport inhibitor), p-chlorophenoxy isobutyric acid (PCIB, auxin action inhibitor), aminoethoxyvinylglycine (AVG, chemical inhibitor of ethylene biosynthesis), or silver ions (Ag(+), ethylene perception antagonist) under low NH4(+) conditions. Our results showed that TIBA, NPA and PCIB did not inhibit root hair elongation under low NH4(+) conditions, while AVG and Ag(+) completely inhibited low NH4(+)-induced root hair elongation. This suggested that low NH4(+)-induced root hair elongation was dependent on the ethylene pathway, but not the auxin pathway. Further genetic studies revealed that root hair elongation in auxin-insensitive mutants was sensitive to low NH4(+) treatment, but elongation was less sensitive in ethylene-insensitive mutants than wild-type plants. In addition, low NH4(+)-induced root hair elongation was accompanied by reactive oxygen species (ROS) accumulation. Diphenylene iodonium (DPI, NADPH oxidase inhibitor) and dimethylthiourea (DMTU, ROS scavenger) inhibited low NH4(+)-induced root hair elongation, suggesting that ROS were involved in this process. Moreover, ethylene acted together with ROS to modulate root hair elongation under low NH4(+) conditions. These results demonstrate that a signaling pathway involving ethylene and ROS participates in regulation of root hair elongation when Arabidopsis seedlings are subjected to low NH4(+) conditions.
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Changhua
authors.initials: C
authors.lastname: Zhu
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Na
authors.initials: N
authors.lastname: Yang
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Zhengfei
authors.initials: Z
authors.lastname: Guo
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Qian
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: ganlj@njau.edu.cn.
authors.forename: Lijun
authors.initials: L
authors.lastname: Gan
mesh_terms: D064751:Ammonium Compounds / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism* / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000378:metabolism; D008954:Models, Biological; D009861:Onium Compounds / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development*; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D064751:Ammonium Compounds; D005030:Ethylenes; D007210:Indoleacetic Acids; D009861:Onium Compounds; D017382:Reactive Oxygen Species; C007517:diphenyleneiodonium; C038983:1,3-dimethylthiourea; C036216:ethylene; D013890:Thiourea; C088137:aminoethoxyvinylglycine; D005998:Glycine
keywords: Ethylene; Low NH(4)(+); ROS; Root hair