Detection and Adaptation in Parasitic Angiosperm Host Selection

Liu, Lizhi; Liu, Yue; Jariwala, Jenil; Lynn, David G.; Palmer, Andrew G.

doi:10.4236/ajps.2016.78123

Cited by 7 publications

(7 citation statements)

References 53 publications

(72 reference statements)

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“…However, QR2 transcripts exhibited strong PhQ-coexpression in P. aegyptiaca (kPhQ =4) and S. hermonthica (kPhQ =3)( Fig. 3E), in line with QR2 responsiveness to HIFs during haustorium formation of Phtheirospermum japonicum and S. asiatica (23,24). These findings, along with the reported PM-association of AtQR2s (25), support QR2 involvement in the PM redox system.…”

supporting

confidence: 77%

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Plasma Membrane Phylloquinone Biosynthesis in Nonphotosynthetic Parasitic Plants

Gu¹,

Chen²,

Nyamdari³

et al. 2018

Preprint

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Phylloquinone (PhQ) is found predominantly in thylakoid membranes of photosynthetic tissues where it functions in photosystem I electron transport. PhQ has also been detected in plasma membranes, but neither the molecular basis nor the significance of this noncanonical pathway has been elucidated. Here we provide evidence of plasma membrane PhQ biosynthesis in a non-photosynthetic holoparasite Phelipanche aegyptiaca. A nonphotosynthetic role is supported by transcription of the entire suite of PhQ biosynthetic genes, plasma membrane-localization of the terminal enzymes, and detection of PhQ in Phelipanche seeds. Analysis of PhQ-coexpressed genes in the holoparasite revealed increased cellular commitment to oxidation-reduction and defense relative to photosynthetic parasites. Coexpression network inference identified oxidoreductases involved in plasma membrane electron transport, implicating PhQ in a transmembrane redox relay associated with parasitism. Plasma membrane PhQ biosynthesis is also predicted to occur in photoautotrophic taxa via alternative splicing, suggesting nonplastidial PhQ is evolutionarily conserved.

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supporting

confidence: 77%

“…We found only one NOX ortholog in the S. hermonthica network (Fig. 3F, kPhQ = 3), and its counterpart in S. asiatica (SaNOX1) was recently shown to be root-specific and HIF-responsive (24). The P. aegyptiaca transcriptome lacked NOX1, but a ferric-chelate reductase (PaFRO1) exhibited strong PhQ-coexpression (kPhQ = 4)( Fig.…”

mentioning

confidence: 91%

Plasma Membrane Phylloquinone Biosynthesis in Nonphotosynthetic Parasitic Plants

Gu¹,

Chen²,

Nyamdari³

et al. 2018

Preprint

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“…BQ-initiated reduction of ROS production in S . asiatica has been correlated with down-regulation of the NADPH oxidase 1, SaNOX1 [ 35 ], which contains two Ca 2+ -binding EF-hand domains. The activity of EF-hand containing NADPH oxidases has been positively correlated with Ca 2+ concentrations in A .…”

Section: Resultsmentioning

confidence: 99%

“…However, unlike traditional quorum sensing signals (autoinducers) that are synthesized by individuals, ROS/quinone networks arise from a dynamic chemical reaction that depends on two distinct partners. The growing plant root meristem, which has relatively low cell wall phenol densities [ 24 , 35 ], provides reactive oxygen species, while another more mature root provides the requisite phenols, allowing this process to serve as an active detection system for the presence of neighboring mature root surfaces.…”

Section: Discussionmentioning

confidence: 99%

“…Our recent investigations of the differential expression of S . asiatica genes following exposure to DMBQ have shown a dramatic decrease in expression of a specific Ca 2+ -regulated NADPH oxidase ( SaNOX1 ) during haustorial development [ 35 ]. Consistent with the mechanism proposed in Fig 7 , reduction of SaNOX1 activity will decrease the rate of DMBQ cycling and ROS generation.…”

Section: Discussionmentioning

confidence: 99%

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Redox-mediated quorum sensing in plants

et al. 2017

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The rhizosphere, the narrow zone of soil around plant roots, is a complex network of interactions between plants, bacteria, and a variety of other organisms. The absolute dependence on host-derived signals, or xenognosins, to regulate critical developmental checkpoints for host commitment in the obligate parasitic plants provides a window into the rhizosphere’s chemical dynamics. These sessile intruders use H2O2 in a process known as semagenesis to chemically modify the mature root surfaces of proximal host plants and generate p-benzoquinones (BQs). The resulting redox-active signaling network regulates the spatial and temporal commitments necessary for host attachment. Recent evidence from non-parasites, including Arabidopsis thaliana, establishes that reactive oxygen species (ROS) production regulates similar redox circuits related to root recognition, broadening xenognosins’ role beyond the parasites. Here we compare responses to the xenognosin dimethoxybenzoquinone (DMBQ) between the parasitic plant Striga asiatica and the non-parasitic A. thaliana. Exposure to DMBQ simulates the proximity of a mature root surface, stimulating an increase in cytoplasmic Ca2+ concentration in both plants, but leads to remarkably different phenotypic responses in the parasite and non-parasite. In S. asiatica, DMBQ induces development of the host attachment organ, the haustorium, and decreases ROS production at the root tip, while in A. thaliana, ROS production increases and further growth of the root tip is arrested. Obstruction of Ca2+ channels and the addition of antioxidants both lead to a decrease in the DMBQ response in both parasitic and non-parasitic plants. These results are consistent with Ca2+ regulating the activity of NADPH oxidases, which in turn sustain the autocatalytic production of ROS via an external quinone/hydroquinone redox cycle. Mechanistically, this chemistry is similar to black and white photography with the emerging dynamic reaction-diffusion network laying the foundation for the precise temporal and spatial control underlying rhizosphere architecture.

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