Nitric Oxide Overproduction by cue1 Mutants Differs on Developmental Stages and Growth Conditions

Abstract

The cue1 nitric oxide (NO) overproducer mutants are impaired in a plastid phosphoenolpyruvate/phosphate translocator, mainly expressed in Arabidopsis thaliana roots. cue1 mutants present an increased content of arginine, a precursor of NO in oxidative synthesis processes. However, the pathways of plant NO biosynthesis and signaling have not yet been fully characterized, and the role of CUE1 in these processes is not clear. Here, in an attempt to advance our knowledge regarding NO homeostasis, we performed a deep characterization of the NO production of four different cue1 alleles (cue1-1, cue1-5, cue1-6 and nox1) during seed germination, primary root elongation, and salt stress resistance. Furthermore, we analyzed the production of NO in different carbon sources to improve our understanding of the interplay between carbon metabolism and NO homeostasis. After in vivo NO imaging and spectrofluorometric quantification of the endogenous NO levels of cue1 mutants, we demonstrate that CUE1 does not directly contribute to the rapid NO synthesis during seed imbibition. Although cue1 mutants do not overproduce NO during germination and early plant development, they are able to accumulate NO after the seedling is completely established. Thus, CUE1 regulates NO homeostasis during post-germinative growth to modulate root development in response to carbon metabolism, as different sugars modify root elongation and meristem organization in cue1 mutants. Therefore, cue1 mutants are a useful tool to study the physiological effects of NO in post-germinative growth.

Nitric Oxide Alters the Pattern of Auxin Maxima and PIN-FORMED1 During Shoot Development

“…Plants were grown on plates containing a modified MS medium optimized for root growth, MSR [2.3 g/L MS (Duchefa Biochemie, Haarlem, The Netherlands), 15 g/L agar], supplemented with glucose as indicated in Lechón et al (2020) . After full germination, root growth was captured by scanning plates with an Epson flatbed scanner and a resolution set to 600 ppi.…”

Salicylic Acid and Nitric Oxide: Insight Into the Transcriptional Regulation of Their Metabolism and Regulatory Functions in Plants

“…Among all the mutants created, six exhibited mutation on single locus NOX1 (NADPH oxidase 1), a close homolog of CUE1 (Chlorophyll a/b binding unexpressed 1). The CUE1 is responsible for synthesizing chloroplast phosphoenolpyruvate/phosphate translocator, which is involved in various physiological processes and NO production in plants (Lechon et al, 2020). These NOX1 (CUE1) mutants displayed intense disorganization of chloroplast phosphoenolpyruvate/phosphate translocator, which suppressed vital physiological processes, including photosynthesis and electron transport system (Lechon et al, 2020).…”

“…The CUE1 is responsible for synthesizing chloroplast phosphoenolpyruvate/phosphate translocator, which is involved in various physiological processes and NO production in plants (Lechon et al, 2020). These NOX1 (CUE1) mutants displayed intense disorganization of chloroplast phosphoenolpyruvate/phosphate translocator, which suppressed vital physiological processes, including photosynthesis and electron transport system (Lechon et al, 2020). Additionally, NOX1 (CUE1) mutants exhibited late flowering compared to non-mutant counterparts, as the former have elevated NO levels due to increased synthesis (Yun et al, 2016).…”