scholarly journals ALLENE OXIDE SYNTHASE and HYDROPEROXIDE LYASE, Two Non-Canonical Cytochrome P450s in Arabidopsis thaliana and Their Different Roles in Plant Defense

2019 ◽  
Vol 20 (12) ◽  
pp. 3064 ◽  
Author(s):  
Sachin Rustgi ◽  
Armin Springer ◽  
ChulHee Kang ◽  
Diter von Wettstein ◽  
Christiane Reinbothe ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Defense ◽  
Metabolic Regulation ◽  
Insect Pests ◽  
Green Leaf Volatiles ◽  
Hydroperoxide Lyase ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Cytochrome P450 Enzymes ◽  
Oxide Synthase

The channeling of metabolites is an essential step of metabolic regulation in all living organisms. Multifunctional enzymes with defined domains for metabolite compartmentalization are rare, but in many cases, larger assemblies forming multimeric protein complexes operate in defined metabolic shunts. In Arabidopsis thaliana, a multimeric complex was discovered that contains a 13-lipoxygenase and allene oxide synthase (AOS) as well as allene oxide cyclase. All three plant enzymes are localized in chloroplasts, contributing to the biosynthesis of jasmonic acid (JA). JA and its derivatives act as ubiquitous plant defense regulators in responses to both biotic and abiotic stresses. AOS belongs to the superfamily of cytochrome P450 enzymes and is named CYP74A. Another CYP450 in chloroplasts, hydroperoxide lyase (HPL, CYP74B), competes with AOS for the common substrate. The products of the HPL reaction are green leaf volatiles that are involved in the deterrence of insect pests. Both enzymes represent non-canonical CYP450 family members, as they do not depend on O2 and NADPH-dependent CYP450 reductase activities. AOS and HPL activities are crucial for plants to respond to different biotic foes. In this mini-review, we aim to summarize how plants make use of the LOX2–AOS–AOC2 complex in chloroplasts to boost JA biosynthesis over volatile production and how this situation may change in plant communities during mass ingestion by insect pests.

scholarly journals Substrate channeling in oxylipin biosynthesis through a protein complex in the plastid envelope of Arabidopsis thaliana

2018 ◽  
Author(s):  
Stephan Pollmann ◽  
Armin Springer ◽  
Sachin Rustgi ◽  
Diter von Wettstein ◽  
ChulHee Kang ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Insect Pests ◽  
Fine Tuning ◽  
Hydroperoxide Lyase ◽  
Allene Oxide ◽  
Cytochrome P450 Enzymes ◽  
Defense Compounds ◽  
Plastid Envelope ◽  
Volatile Aldehydes ◽  
Abiotic Stimuli

ABSTRACTOxygenated membrane fatty acid derivatives dubbed oxylipins play important roles in the plant’s defense against biotic and abiotic cues. Plants challenged by insect pests, for example, synthesize a blend of different defense compounds that, amongst others, comprise volatile aldehydes and jasmonic acid (JA). Because all oxylipins are derived from the same pathway, we asked how their synthesis might be regulated and focused on two closely related, atypical cytochrome P450 enzymes designated CYP74A and CYP74B, i.e., allene oxide synthase (AOS) and hydroperoxide lyase (HPL). Both enzymes compete for the same substrate but give rise to different products. While the final product of the AOS branch is JA, those of the HPL branch comprise volatile aldehydes and alcohols. AOS and HPL are plastid envelope enzymes in Arabidopsis thaliana but accumulate at different locations. Biochemical experiments identified AOS as constituent of complexes also containing lipoxygenase 2 (LOX2) and allene oxide cyclase (AOC), which catalyze consecutive steps in JA precursor biosynthesis, while excluding the concurrent HPL reaction. Based on published X-ray data, the structure of this complex could be modelled and amino acids involved in catalysis and subunit interactions identified. Genetic studies identified the microRNA 319 (miR319)-regulated clade of TCP (TEOSINTE BRANCHED/CYCLOIDEA/PCF) transcription factor genes and CORONATINE INSENSITIVE 1 (COI1) to control JA production through the AOS-LOX2-AOC2 complex. Together, our results define a molecular branch point in oxylipin biosynthesis that allows fine-tuning the plant’s defense machinery in response to biotic and abiotic stimuli.

Allene oxide synthase and hydroperoxide lyase product accumulation in Artemisia species

Plant Science ◽  
2005 ◽  
Vol 169 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Meshack Afitlhile ◽  
Hirotada Fukushige ◽  
Charles McCraken ◽  
David Hildebrand
Keyword(s):  
Hydroperoxide Lyase ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Artemisia Species ◽  
Oxide Synthase ◽  
Product Accumulation

Structure and regulation of the Arabidopsis thaliana allene oxide synthase gene

Planta ◽  
1999 ◽  
Vol 208 (4) ◽  
pp. 463-471 ◽  
Author(s):  
I. Kubigsteltig ◽  
D. Laudert ◽  
E. W. Weiler
Keyword(s):  
Arabidopsis Thaliana ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Oxide Synthase

Regulation of oxylipin synthesis

2000 ◽  
Vol 28 (6) ◽  
pp. 847-849 ◽  
Author(s):  
D. F. Hildebrand ◽  
M. Afitlhile ◽  
H. Fukushige
Keyword(s):  
Fatty Acids ◽  
Plant Species ◽  
Citrullus Lanatus ◽  
Product Formation ◽  
Hydroperoxide Lyase ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Esterified Fatty Acids ◽  
Oxide Synthase ◽  
Fatty Acid Hydroperoxides

Two very common groups of oxylipins formed in plants involve the conversion of fatty acid hydroperoxides, such as hydroperoxy-octadecatrienoic acid, into further metabolites by allene oxide synthase and hydroperoxide lyase. Both of these oxylipin branch pathways appear to be ubiquitous or nearly so in plants, but the relative activities of these two branches vary among plant species. In most plants examined, including Arabidopsis product formation from either of these pathways is minimal until elicited by wounding or some other means, upon which products from both pathways, such as jasmonic acid and C6 aldehydes and alcohols, can increase by orders of magnitude. In some plant species such as Artemisia and Jasminum spp. oxylipin product formation is heavily skewed towards allene oxide synthase products. Others such as watermelon (Citrullus lanatus) produce 10-fold higher amounts or more of hydroperoxide lyase than allene oxide synthase products. Arabidopsis and tobacco are intermediate between these extremes. Artemisia and Jasminum are also unusual in that they do not require wounding or other types of induction for high oxylipin product formation. Release of non-esterified fatty acids appears to be correlated with oxylipin formation, but phospholipase A2 appears not to be involved with oxylipin production, at least in the case of Artemisia leaves.

scholarly journals Expression of Castanea crenata Allene Oxide Synthase in Arabidopsis Improves the Defense to Phytophthora cinnamomi

2020 ◽  
Author(s):  
Susana Serrazina ◽  
Helena Machado ◽  
Rita Costa ◽  
Paula Duque ◽  
Rui Malhó
Keyword(s):  
Arabidopsis Thaliana ◽  
Jasmonic Acid ◽  
Stress Responses ◽  
Phytophthora Cinnamomi ◽  
Defense Responses ◽  
Confocal Imaging ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Castanea Crenata ◽  
Oxide Synthase

ABSTRACTAllene oxide synthase (AOS) is a key enzyme of the jasmonic acid (JA) signaling pathway. The AOS gene was previously found to be upregulated in an Asian chestnut species resistant to infection by the oomycete Phytophthora cinnamomi (Castanea crenata), while lower expression values were detected in the susceptible European chestnut (Castanea sativa). Here, we report a genetic and functional characterization of the C. crenata AOS (CcAOS) upon its heterologous gene expression in a susceptible ecotype of Arabidopsis thaliana, which contains a single AOS gene. It was found that Arabidopsis plants expressing CcAOS delay pathogen progression and exhibit more vigorous growth in its presence. They also show upregulation of jasmonic acid and salicylic acid-related genes. As in its native species, heterologous CcAOS localized to plastids, as revealed by confocal imaging of the CcAOS-eGFP fusion protein in transgenic Arabidopsis roots. This observation was confirmed upon transient expression in Nicotiana benthamiana leaf epidermal cells. To further confirm a specific role of CcAOS in the defense mechanism against the pathogen, we performed crosses between transgenic CcAOS plants and an infertile Arabidopsis AOS knockout mutant line. It was found that plants expressing CcAOS exhibit normal growth, remain infertile but are significantly more tolerant to the pathogen than wild type plants.Together, our results indicate that CcAOS is an important player in plant defense responses against oomycete infection and that its expression in susceptible varieties may be a valuable tool to mitigate biotic stress responses.One-sentence summaryHeterologous expression of the Castanea crenata allene oxide synthase gene in Arabidopsis thaliana improves the defense response to the pathogen Phytophthora cinnamomi.

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