title: Nitric oxide accumulation in Arabidopsis is independent of NOA1 in the presence of sucrose.
abstract: Nitric oxide signals diverse responses in animals and plants. Whereas nitric oxide synthesis mechanisms in animals are well understood, how nitric oxide is synthesized and regulated in plants remains controversial. NOA1 is a circularly permuted GTPase that is important for chloroplast function and is implicated in nitric oxide synthesis. However, the reported consequences of a null mutation in NOA1 are inconsistent. Whereas some studies indicate that the noa1 mutant has severe reductions in nitric oxide accumulation, others report that nitric oxide levels are indistinguishable between noa1 and the wild type. Here, we identify a correlation between the reported ability of noa1 to accumulate nitric oxide with growth on sucrose-supplemented media. We report that noa1 accumulates both basal and salicylic acid-induced nitric oxide only when grown on media containing sucrose. In contrast, nitric oxide accumulation in wild type is largely insensitive to sucrose supplementation. When grown in the absence of sucrose, noa1 has low fumarate, pale green leaves, slow growth and reduced chlorophyll content. These phenotypes are consistent with a defect in chloroplast-derived photosynthate production and are largely rescued by sucrose supplementation. We conclude that NOA1 has a primary role in chloroplast function and that its effects on the accumulation of nitric oxide are likely to be indirect.
authors.affiliation: Biochemistry and Cell Biology, Rice University, Houston, TX 77005-1892, USA.
authors.forename: Kalie
authors.initials: K
authors.lastname: Van Ree
authors.forename: Bernadette
authors.initials: B
authors.lastname: Gehl
authors.forename: E Wassim
authors.initials: EW
authors.lastname: Chehab
authors.forename: Yu-Chang
authors.initials: YC
authors.lastname: Tsai
authors.forename: Janet
authors.initials: J
authors.lastname: Braam
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018533:Biomass; D002734:Chlorophyll / Q000032:analysis; D002736:Chloroplasts / Q000378:metabolism; D005650:Fumarates / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D050901:Nitrate Reductase / Q000235:genetics / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D018520:Plant Shoots / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D020156:Salicylic Acid / Q000494:pharmacology; D036226:Seedlings / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D017384:Sequence Deletion; D015398:Signal Transduction; D013395:Sucrose / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D005650:Fumarates; D012333:RNA, Messenger; D018749:RNA, Plant; D002734:Chlorophyll; D009569:Nitric Oxide; D013395:Sucrose; C521947:NOA1 protein, Arabidopsis; D019001:Nitric Oxide Synthase; D050901:Nitrate Reductase; D020558:GTP Phosphohydrolases; D020156:Salicylic Acid