UV-A/Blue-Light responses in algae

All life on earth depends on light. A variety of photoreceptors capture the light for a wide range of reactions. Photosynthetic organisms absorb the light necessary for energy transformation and charge separation facilitating photosynthesis. In addition to the bulk pigments there is a great diversity of photoreceptors present in minute concentrations that control development, metabolism and orientation of plants and microorganisms. Based on its spectral absorbance, the well-studied phytochrome system acts in the RL (red light) region as well as in the UV-A/BL (blue light) region where the above mentioned reactions are mediated by a variety of photoreceptors whose natures are largely unknown. Phyllogenetically the UV-A/BL photoreceptors seem to be more ancient pigments that eventually were replaced by the phytochrome system. However, there are many reports that suggest a coaction between the UV-A/BL receptors and the phytochrome system. In several cases the UV-A/BL activation is the prerequisite for the phytochrome reaction. Historically it was the German botanist Julius Sachs who first discovered in 1864 that phototropism in plants was due to BL reactions. It took over 70 years until Bunning (1937) and Galston and Baker (1949) rediscovered the BL response. Since then, an ever-increasing attention has been paid to this effect. In this contribution, the general aspect of UV-A/BL responses and especially the responsiveness of algae will be covered

Differential Display Analysis of the Early Compatible Interaction Between Soybean and the Soybean Cyst Nematode

The marked cellular changes during feeding site formation of the soybean cyst nematode (Heterodera glycines) indicate major changes in soybean gene expression. We used differential display of mRNA to detect host gene expression changes during the early compatible interaction between soybean and H. glycines. Fifteen cDNA clones corresponding to mRNAs with different abundances in H. glycines-infected versus uninfected roots were identified. Differential display results indicated that abundances of five mRNAs increased in infected roots, whereas abundances of 10 mRNAs decreased. Transcripts for nine of these 15 cDNAs could be detected on RNA blots, and their hybridization signals confirmed the differential display results for eight of these nine cDNAs. Sequence analyses identified five cDNAs with decreased mRNA levels in infected roots as corresponding to two putative aldolase genes, a transcription-factor TFIIA homologue, the soybean small GTP-binding protein gene sra1, and the soybean auxin down-regulated gene ADR12. RNA blot analyses of other auxin down-regulated genes revealed a decrease in their mRNA abundances in H. glycines-infected roots as well

Changes in mRNA Abundance within Heterodera schachtii-Infected Roots of Arabidopsis thaliana

Gene expression changes in plant roots infected by plant-parasitic cyst nematodes are involved in the formation of nematode feeding sites. We analyzed mRNA abundance changes within roots of Arabidopsis thaliana during the early compatible interaction with Heterodera schachtii, the sugarbeet cyst nematode. Approximately 1,600 root sections, each containing a single parasitic nematode and its feeding site, and 1,600 adjacent, nematode-free root sections were excised from aseptic A. thaliana cultures 3 to 4 days after inoculation with H. schachtii. These tissue samples were termed infected and uninfected, respectively. Preparasitic nematodes were added to the uninfected tissue sample to maintain the nematode to plant tissue proportion. mRNA extracted from these two tissue samples was subjected to differential display analysis. Thirty-six cDNA clones corresponding to mRNA species with different abundance between both tissue samples were isolated. Of these clones, 24 were of A. thaliana origin and 12 were from H. schachtii. Differential display data predicted that the A. thaliana cDNA clones corresponded to 13 transcripts that were more abundant in the infected root sections and 11 transcripts that were more abundant in the uninfected root sections. H. schachtii cDNA clones were predicted to correspond to four transcripts that were more abundant in parasitic nematodes and to eight transcripts that were more abundant in preparasitic nematodes. In situ hybridization experiments confirmed the mRNA abundance changes in A. thalianaroots predicted by the differential display analyses for two A. thaliana clones

Molecular Interactions between the Specialist Herbivore Manduca sexta (Lepidoptera, Sphingidae) and Its Natural Host Nicotiana attenuata. II. Accumulation of Plant mRNAs in Response to Insect-Derived Cues

The transcriptional changes in Nicotiana attenuata Torr. ex Wats. elicited by attack from Manduca sexta larvae were previously characterized by mRNA differential display (D. Hermsmeier, U. Schittko, I.T. Baldwin [2001] Plant Physiol 125: 683–700). Because herbivore attack causes wounding, we disentangled wound-induced changes from those elicited by M. sexta oral secretions and regurgitant (R) with a northern analysis of a subset of the differentially expressed transcripts encoding threonine deaminase, pathogen-induced oxygenase, a photosystem II light-harvesting protein, a retrotransposon homolog, and three unknown genes. R extensively modified wound-induced responses by suppressing wound-induced transcripts (type I) or amplifying the wound-induced response (type II) further down-regulating wound-suppressed transcripts (type IIa) or up-regulating wound-induced transcripts (type IIb). It is interesting that although all seven genes displayed their R-specific patterns in the treated tissues largely independently of the leaf or plant developmental stage, only the type I genes displayed strong systemic induction. Ethylene was not responsible for any of the specific patterns of expression. R collected from different tobacco feeding insects, M. sexta, Manduca quinquemaculata, and Heliothis virescens, as well as from different instars of M. sexta were equally active. The active components of M. sexta R were heat stable and active in minute amounts, comparable with real transfer rates during larval feeding. Specific expression patterns may indicate that the plant is adjusting its wound response to efficiently fend off M. sexta, but may also be advantageous to the larvae, especially when R suppress wound-induced plant responses

Differential Display Analysis of the Early Compatible Interaction Between Soybean and the Soybean Cyst Nematode

The marked cellular changes during feeding site formation of the soybean cyst nematode (Heterodera glycines) indicate major changes in soybean gene expression. We used differential display of mRNA to detect host gene expression changes during the early compatible interaction between soybean and H. glycines. Fifteen cDNA clones corresponding to mRNAs with different abundances in H. glycines-infected versus uninfected roots were identified. Differential display results indicated that abundances of five mRNAs increased in infected roots, whereas abundances of 10 mRNAs decreased. Transcripts for nine of these 15 cDNAs could be detected on RNA blots, and their hybridization signals confirmed the differential display results for eight of these nine cDNAs. Sequence analyses identified five cDNAs with decreased mRNA levels in infected roots as corresponding to two putative aldolase genes, a transcription-factor TFIIA homologue, the soybean small GTP-binding protein gene sra1, and the soybean auxin down-regulated gene ADR12. RNA blot analyses of other auxin down-regulated genes revealed a decrease in their mRNA abundances in H. glycines-infected roots as well.This article is published as Hermsmeier, Dieter, Mitra Mazarei, and Thomas J. Baum. "Differential display analysis of the early compatible interaction between soybean and the soybean cyst nematode." Molecular plant-microbe interactions 11, no. 12 (1998): 1258-1263, doi: 10.1094/MPMI.1998.11.12.1258. Posted with permission.</p

Changes in mRNA Abundance within Heterodera schachtii-Infected Roots of Arabidopsis thaliana

Gene expression changes in plant roots infected by plant-parasitic cyst nematodes are involved in the formation of nematode feeding sites. We analyzed mRNA abundance changes within roots of Arabidopsis thaliana during the early compatible interaction with Heterodera schachtii, the sugarbeet cyst nematode. Approximately 1,600 root sections, each containing a single parasitic nematode and its feeding site, and 1,600 adjacent, nematode-free root sections were excised from aseptic A. thaliana cultures 3 to 4 days after inoculation with H. schachtii. These tissue samples were termed infected and uninfected, respectively. Preparasitic nematodes were added to the uninfected tissue sample to maintain the nematode to plant tissue proportion. mRNA extracted from these two tissue samples was subjected to differential display analysis. Thirty-six cDNA clones corresponding to mRNA species with different abundance between both tissue samples were isolated. Of these clones, 24 were of A. thaliana origin and 12 were from H. schachtii. Differential display data predicted that the A. thaliana cDNA clones corresponded to 13 transcripts that were more abundant in the infected root sections and 11 transcripts that were more abundant in the uninfected root sections. H. schachtii cDNA clones were predicted to correspond to four transcripts that were more abundant in parasitic nematodes and to eight transcripts that were more abundant in preparasitic nematodes. In situ hybridization experiments confirmed the mRNA abundance changes in A. thalianaroots predicted by the differential display analyses for two A. thaliana clones.This article is published as Hermsmeier, Dieter, Jennifer K. Hart, Marina Byzova, Steven R. Rodermel, and Thomas J. Baum. "Changes in mRNA abundance within Heterodera schachtii-infected roots of Arabidopsis thaliana." Molecular plant-microbe interactions 13, no. 3 (2000): 309-315, doi: 10.1094/MPMI.2000.13.3.309. Posted with permission.</p