NO-deficient vs wild type Col-0 Arabidopsis seedlings

Nitric oxide regulates plant development and responses to stress. However, the mechanisms underlying its regulatory role are still poorly known, and the impact of endogenous NO on the genome-wide transcriptome of plants has not been studied. For that purpose, we compared the transcriptomes of NO-deficient nia1nia2, noa1-2 and nia1nia2noa1-2 mutant versus wild type Arabidopsis thaliana plants. A core comprising 66 NO-responsive genes with similar expression in all NO-deficient genotypes was identified. Among them, 46 were down- and 20 up-regulated in NO-deficient plants, and thus positively and negatively regulated by endogenous NO, respectively. Accordingly with changes in its transcriptome, the NO-deficient nia1nia2noa1-2 mutant accumulated anthocyanins and indolic glucosinolates, displayed abnormal iron homeostasis in shoots and roots, and also showed altered root sensitivity to hormones such as ABA, ET, CYK and IAA. Together the presented data suggest NO functions essentially as a modulator of hormone action. Compared analysis of the transcriptomes of 15-day old seedlings from 3 different nitric oxide (NO)-deficient mutant genotypes versus wild type background Col-0 (3 independent biological replicates per genotype). NO-deficient mutant seedlings in Col-0 background were the double nia1nia2 mutant in nitrate reductases (NR/NIA) 1 and 2 (abbreviated as nia); the noa1-2 mutant allele in Nitric Oxide Associated 1 (AtNOA1) (abbreviated as noa); and, the triple nia1nia2noa1-2 (abreviated as nino).