title: Arabidopsis nudix hydrolase 7 plays a role in seed germination.
abstract: Arabidopsis nudix hydrolase 7 (Atnudt7) mutants exhibit reduced seed germination phenotype following after-ripening. The role of AtNUDT7 in seeds and during early stages of imbibition was examined. Seeds of Atnudt7-1 and Col-0 following 3 days of imbibition were used to profile changes in NADH- and ADP-ribose pyrophosphohydrolase enzyme activities, expression of nudix family genes closely related to AtNudt7, and AtNUDT7 protein levels. Changes in pyridine nucleotides, phytohormones, reactive oxygen species and poly(ADP-ribose) levels in after-ripened seeds and 1 day after imbibition were also analyzed. Changes in AtNUDT7 gene expression, protein levels and enzyme activities in WT seeds and during early stages of imbibition were correlated. Atnudt7-1 seeds lacked NADH pyrophosphohydrolase activity that led to very high catabolic redox charge. Abscisic acid (ABA) levels were higher in Atnudt7-1 mutant while salicylic acid, gibberellic acid, and reactive oxygen species (ROS) levels were higher in WT seeds. In Atnudt7-1, there was excess ROS accumulation 1 day after imbibition. PAR levels were significantly higher in Atnudt7-1 mutant when compared to WT during imbibition. Based on these observations, we conclude NADH pyrophosphohydrolase activity conferred by AtNUDT7 is important for NAD:NADH homeostasis in seeds. Perturbations to this key redox couple alter ABA and ROS levels in the seeds that in turn lowers germination.
authors: Department of Biochemistry and Molecular Biology, 246 Noble Research Center, Oklahoma State University, Stillwater, OK, 74078, USA.
authors: Xin
authors: X
authors: Zeng
authors: Yong-Fang
authors: YF
authors: Li
authors: Ramamurthy
authors: R
authors: Mahalingam
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018525:Germination / Q000235:genetics; D005875:Gibberellins / Q000378:metabolism; D008954:Models, Biological; D016254:Mutagenesis, Insertional / Q000235:genetics; D009154:Mutation / Q000235:genetics; D009243:NAD / Q000378:metabolism; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012639:Seeds / Q000201:enzymology* / Q000254:growth & development*; D000096964:Nudix Hydrolases
chemical_list: D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D005875:Gibberellins; D009243:NAD; D011064:Poly Adenosine Diphosphate Ribose; D011755:Pyrophosphatases; D017382:Reactive Oxygen Species; C036483:T-DNA; C007842:gibberellic acid; C545452:NUDX7 protein, Arabidopsis; D000096964:Nudix Hydrolases