Peroxisomal NADP-isocitrate dehydrogenase is required for Arabidopsis stomatal movement

Abstract

Peroxisomes are subcellular organelles characterized by a simple morphological structure but have a complex biochemical machinery involved in signaling processes through molecules such as hydrogen peroxide (H2O2) and nitric oxide (NO). Nicotinamide adenine dinucleotide phosphate (NADPH) is an essential component in cell redox homeostasis, and its regeneration is critical for reductive biosynthesis and detoxification pathways. Plants have several NADPH-generating dehydrogenases, with NADP-isocitrate dehydrogenase (NADP-ICDH) being one of these enzymes. Arabidopsis contains three genes that encode for cytosolic, mitochondrial/chloroplastic, and peroxisomal NADP-ICDH isozymes although the specific function of each of these remains largely unknown. Using two T-DNA insertion lines of the peroxisomal NADP-ICDH designated as picdh-1 and picdh-2, the data show that the peroxisomal NADP-ICDH is involved in stomatal movements, suggesting that peroxisomes are a new element in the signaling network of guard cells.

Defects in Peroxisomal 6-Phosphogluconate Dehydrogenase Isoform PGD2 Prevent Gametophytic Interaction in Arabidopsis thaliana

“…9) seems to be crucial for gametophytic interaction, especially during pollen tube guidance to ovules. Intriguingly, other reactions that may provide NADPH in peroxisomes, especially NADP-ICDH (At1g54340), for which viable mutants exist that are impaired in stomatal movements (Leterrier et al, 2015), and NADK3 (At1g78590), do not compensate, although both (according to the Arabidopsis eFP browser; Winter et al, 2007) are expressed during flower development. Possibly, their activity is either irrelevant or too low in the gametophytes to support the biosynthesis of NO and/or JA to critical levels.…”

Plant peroxisomes: recent discoveries in functional complexity, organelle homeostasis, and morphological dynamics

“…These findings provide a rationale for the occurrence of stomatal oil bodies throughout the plant kingdom [16]. Moreover, Arabidopsis mutants deficient in peroxisomal NADP-dependent isocitrate dehydrogenase (pICDH) are compromised in light-induced stomatal opening [17]. pICDH is one of the few peroxisomal matrix sources of NADPH, which is needed for JA biosynthesis and the peroxisomal ascorbate-glutathione cycle.…”

“…pICDH is one of the few peroxisomal matrix sources of NADPH, which is needed for JA biosynthesis and the peroxisomal ascorbate-glutathione cycle. The stomatal defect of picdh is reversible by either an antioxidant such as ascorbate or a nitric oxide scavenger, suggesting that pICDH regulates peroxisomal H 2 O 2 and/or NO levels and that peroxisomes are needed in guard cells not only for energy metabolism [16], but also for signaling [17]. …”

What is the role of hydrogen peroxide in plant peroxisomes?

“…Thus, this closely correlates with some changes in Arabidopsis where catalase 3 modulates H 2 O 2 homeostasis in stomatal guard cells (Zou et al 2015). Additionally, it has also been reported using Arabidopsis knockout mutants of the peroxisomal NADP-dependent isocitrate dehydrogenase (ICDH; activity participating in detoxification of H 2 O 2 through the ascorbate-glutathione cycle by providing NADPH for glutathione reductase) that peroxisomes are involved in stomatal movement, supporting the suggestion that these organelles are a new element in the signalling network of guard cells (Leterrier et al 2015).…”