title: NO synthase-generated NO acts downstream of auxin in regulating Fe-deficiency-induced root branching that enhances Fe-deficiency tolerance in tomato plants.
abstract: In response to Fe-deficiency, various dicots increase their root branching which contributes to the enhancement of ferric-chelate reductase activity. Whether this Fe-deficiency-induced response eventually enhances the ability of the plant to tolerate Fe-deficiency or not is still unclear and evidence is also scarce about the signals triggering it. In this study, it was found that the SPAD-chlorophyll meter values of newly developed leaves of four tomato (Solanum lycocarpum) lines, namely line227/1 and Roza and their two reciprocal F(1) hybrid lines, were positively correlated with their root branching under Fe-deficient conditions. It indicates that Fe-deficiency-induced root branching is critical for plant tolerance to Fe-deficiency. In another tomato line, Micro-Tom, the increased root branching in Fe-deficient plants was accompanied by the elevation of endogenous auxin and nitric oxide (NO) levels, and was suppressed either by the auxin transport inhibitors NPA and TIBA or the NO scavenger cPTIO. On the other hand, root branching in Fe-sufficient plants was induced either by the auxin analogues NAA and 2,4-D or the NO donors NONOate or SNP. Further, in Fe-deficient plants, NONOate restored the NPA-terminated root branching, but NAA did not affect the cPTIO-terminated root branching. Fe-deficiency-induced root branching was inhibited by the NO-synthase (NOS) inhibitor L-NAME, but was not affected by the nitrate reductase (NR) inhibitor NH(4)(+), tungstate or glycine. Taking all of these findings together, a novel function and signalling pathway of Fe-deficiency-induced root branching is presented where NOS-generated rather than NR-generated NO acts downstream of auxin in regulating this Fe-deficiency-induced response, which enhances the plant tolerance to Fe-deficiency.
authors.affiliation: College of Environmental and Resource Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Chong Wei
authors.initials: CW
authors.lastname: Jin
authors.forename: Shao Ting
authors.initials: ST
authors.lastname: Du
authors.forename: Imran Haider
authors.initials: IH
authors.lastname: Shamsi
authors.forename: Bing Fang
authors.initials: BF
authors.lastname: Luo
authors.forename: Xian Yong
authors.initials: XY
authors.lastname: Lin
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism; D001565:Benzoates / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005998:Glycine / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D000090463:Iron Deficiencies; D018551:Solanum lycopersicum / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000378:metabolism; D009280:Naphthaleneacetic Acids / Q000378:metabolism / Q000494:pharmacology; D050901:Nitrate Reductase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D015398:Signal Transduction; D014283:Triiodobenzoic Acids / Q000494:pharmacology; D017973:Tungsten Compounds / Q000494:pharmacology
chemical_list: D001565:Benzoates; D004791:Enzyme Inhibitors; D007093:Imidazoles; D007210:Indoleacetic Acids; D009280:Naphthaleneacetic Acids; D020030:Nitric Oxide Donors; D010937:Plant Growth Regulators; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds; D014283:Triiodobenzoic Acids; D017973:Tungsten Compounds; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; D015084:2,4-Dichlorophenoxyacetic Acid; D009569:Nitric Oxide; C034182:1-naphthaleneacetic acid; D007501:Iron; D010088:Oxidoreductases; C034747:nitric-oxide reductase; D050901:Nitrate Reductase; C052968:2,3,5-triiodobenzoic acid; C045951:tungstate; D005998:Glycine; D019331:NG-Nitroarginine Methyl Ester